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Sand Transport Rates at Jupiter Inlet, Florida


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SAND TRANSPORT RATES AT JUPITER INLET, FLORIDA By SHIRSHANT SHARMA A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2007 1

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2007 Shirshant Sharma 2

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to my parents 3

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ACKNOWLEDGMENTS I am sincerely thankful to my advisor and supervisory committee chairman, Dr. Ashish J. Mehta, for his guidance. I would also like to thank supervisory committee members Dr. Arnoldo Valle-Levinson, Dr. Tian-Jian Hsu, and Dr. John J aeger. Sincere acknowledgment is due to Dr. Earl J. Hayter and to Ms. Mamta Jain for thei r guidance and effort, and also in helping me understand the basic concepts of modeling done in the thesis. Dr. Andrew Kennedy provided most of the information given in Appe ndix A, and programming for Appendix C. Support for this study was provided by the Jupiter Inlet District Commission, Jupiter, Florida. Considerable help was provided by Mr. Michael Grella, Executiv e Director, for making districts and other data available for analysis. I must extend thanks to my grandparents, my parents, my sister, my brother-in-law, and Shweta for the unlimited support and blessings. Thanks are due to Mr. Sidney L. Schofield of the Coastal and Oceanographic Engineering Laboratory for providing field data and guiding me in their analysis I would also like to express my thanks to the faculty and staff of the Depart ment of Civil and Coastal Engineering for their help during my study. Finally, I am thankful to God. 4

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TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES ...........................................................................................................................7 LIST OF FIGURES .........................................................................................................................9 LIST OF SYMBOLS .....................................................................................................................13 ABSTRACT ...................................................................................................................................15 CHAPTER 1 INTRODUCTION................................................................................................................. .17 1.1 Problem Statement ............................................................................................................17 1.2 Objective and Tasks ..........................................................................................................18 2 FIELD STUDY.................................................................................................................. .....19 2.1 Site Description ................................................................................................................19 2.2 Fixed-Point Data ...............................................................................................................20 2.2.1 Data Collection using ADCP ..................................................................................20 2.2.2 Analysis of ADCP Data for Station 1 .....................................................................22 2.2.3 Water Sampling ......................................................................................................22 2.2.4 Analysis of Niskin Bottle Data ...............................................................................23 2.3 Underway Data .................................................................................................................24 2.3.1 Data Collection .......................................................................................................24 2.3.2 Analysis of Underway Data ....................................................................................24 3 SEDIMENT LOAD ESTIMATION.......................................................................................38 3.1 Introduction .......................................................................................................................38 3.2 Model Setup ......................................................................................................................38 3.3 Seaward Sediment Boundary Condition ...........................................................................39 3.4 Model Operation ...............................................................................................................41 3.5 Sediment Loads ................................................................................................................42 4 SAND BUDGETS................................................................................................................. .52 4.1 Introduction .......................................................................................................................52 4.2 Sand Budget for Eastern Zone ..........................................................................................52 4.3 Data Sources .....................................................................................................................53 4.3.1 Types of Data .........................................................................................................53 4.3.1.1 Shoreline data ...............................................................................................53 5

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4.3.1.2 Beach nourishment .......................................................................................55 4.4 Sand Budget Analysis .......................................................................................................55 4.5 Sand Budget for Western Zone .........................................................................................57 5 SUMMARY AND CONCLUSIONS.....................................................................................71 5.1 Summary ...........................................................................................................................71 5.2 Conclusions.......................................................................................................................71 5.3 Recommendations for Further Work ................................................................................72 APPENDIX A WAVE-INDUCED SAND MOBILITY.................................................................................74 A.1 Wave Data ........................................................................................................................74 A.2 Sediment Movement ........................................................................................................76 B SHORELINE AND BEAC H VOLUME CHANGES............................................................80 C ESTIMATION OF SHORELINE CH ANGE FROM AERIAL IMAGERY.........................92 D BASIS FOR THE LENGTH OF SOUTH JETTY EXTENSION..........................................98 D.1 Introduction ......................................................................................................................98 D.2 Outcome of Hydr aulic Modeling Tests .........................................................................100 D.3 Assessment of Jetty based on Shadow Effect ................................................................102 LIST OF REFERENCES .............................................................................................................105 BIOGRAPHICAL SKETCH .......................................................................................................107 6

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LIST OF TABLES Table page 2-1 Shear stress at ebb flow and flood flow .............................................................................36 2-2 d25, d50, d75 and So values for different times on March 01, 2006 ......................................37 3-1 Concentrations and grain sizes ( d) used by Alkhalidi (2005) as inlet boundary condition in the 16 boundary cells. ....................................................................................49 3-2 Time-averaged concentrations for seaward boundary condition in kg/m3........................49 3-3 Results from model compared with sampling data of March 1, 2006 ...............................49 3-4 Volumetric rates of sand transport in Central Embayment ................................................51 4-1 Components of sand budget for the eastern zone ..............................................................65 4-2 FDEP surveys for Martin and Palm Beach Counties .........................................................65 4-3 Jupiter Inlet updr ift beach nourishment volumes (Odroniec, 2006) ..................................65 4-4 Volume change rates updrif t and downdrift of Jupiter Inlet ..............................................66 4-5 JID surveys in Palm Beach County ...................................................................................66 4-6 Jupiter Inlet trap dredgi ng and placement volumes, 1952-1995 ........................................67 4-7 Annual sand transport rates near Ju piter Inlet, 1952-1988 (Mehta et al., 1991). ...............68 4-8 Annual sand transport rates in the eastern zone for 1974-1986 FDEP budget. .................68 4-9 Annual sand transport rates in the eastern zone for 1986-2002 FDEP budget ..................68 4-10 Annual sand transport rates in th e eastern zone for 1993-1998 JID sand budget ..............69 4-11 Annual sand transport rates in th e eastern zone for 1998-2006 JID sand budget ..............69 4-12 Rates of accumulation in JID sand trap and ICWW ..........................................................69 4-13 Jetty preand post-extension volume changes on 1.2 km of south beach .........................70 4-14 Definitions of components of western zone sediment budget. ..........................................70 4-15 Annual mean sand transport rates in the western zone. .....................................................70 A-1 Types of sediment transport and freque ncy of occurrence at th e inlet in 3 m depth .........78 7

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C-1 Coordinates and elevatio ns of the control points. ..............................................................95 8

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LIST OF FIGURES Figure page 2-1 Location map of the study area ..........................................................................................26 2-2 Jupiter Inlet, Central Embayment and tributaries ..............................................................27 2-3 Location of sand trap in Jupiter Inlet channel ....................................................................27 2-4 Fixed-point sampling St ation 1 (26.28 N and 80 04.68 W) and Station 2 (26.04 N and 80.34 W) ..............................................................................28 2-5 Supporting structure for the ADCP....................................................................................28 2-6 Current velocities recorded at f our elevations on 03/01/06 at Station 1. ...........................29 2-7 Velocity profiles at selected times during flood flow on 03/01/07. ...................................29 2-8 Velocity profiles at selected times during ebb flow on 03/01/07. .....................................30 2-9 Depth-averaged resultant velocity record ed between 02/16/06 to 03/02/06 at Station 1..........................................................................................................................................30 2-10 Suspended sediment concentration time-series at Station 1 on 03/01/06. .........................31 2-11 Depth-averaged velocity tim e-series at St ation 1 on 03/01/06. .........................................31 2-12 Suspended sediment flux time-series at 1.2 m elevation at Station 1 on 03/01/06. ...........32 2-13 Three transects for underway data collection ....................................................................32 2-14 Calibration curve of sediment concentrati on versus backscatter intensity at Jupiter Inlet. ...................................................................................................................................33 2-15 Plot of u versus v and the rotation angle = 169o to calculate the resultant velocity at Transect 1. Positive values denote flood flow. ..................................................................33 2-16 Velocity distribution at Transect 1 for water flowing in at 8:00 pm on 05/09/06. At that time the incoming suspende d sediment flux was maximum. .....................................34 2-17 Velocity distribution at Transect 1 for water flowing out at 2:30 pm on 05/09/06. At that time the outgoing suspended sediment flux was maximum. ......................................34 2-18 Suspended sediment flux distribution at Transect 1 at 8:00 pm on 05/09/06, when incoming cross-sectional mean flux was at its peak. .........................................................35 2-19 Suspended sediment flux distribution at Transect 1 at 2:30 pm on 05/09/06, when outgoing cross-sectional mean flux was at its peak. ..........................................................35 9

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2-20 Time-series of cross-sectional aver aged flux at three transects based on measurements on 05/09/06. ...............................................................................................36 3-1 Loxahatchee estuary in Cartesian grid with six flow boundaries and seagrass (green areas). .................................................................................................................................43 3-2 Concentration time-series for cells in co lumn 1 (south end of Transect 1) at the seaward boundary on 05/09/06. .........................................................................................43 3-3 Concentration time-series for cells in column 2 at the seaward boundary on 05/09/06. ...44 3-4 Concentration time-series for cells in column 3 at the seaward boundary 05/09/06. ........45 3-5 Concentration time-series for cells in co lumn 4 (north end of transect 1) at the seaward boundary on 05/09/06. .........................................................................................46 3-6 Contour plot of time-averaged concentr ations used to spec ify seaward boundary condition. Color scale represents concentrati on in mg/L. Depth and width of grid are dimensionless. ....................................................................................................................46 3-7 Tidal plot for September 29 September 30, 2000 at FECRR bridge ...............................47 3-8 Tidal plot for February 28 March 1, 2006 at FECRR bridge .........................................47 3-9 Transects C, D, F and H where sedime nt fluxes and loads we re calculated. Color scale represents depth in meters. ........................................................................................48 3-10 Total load versus time plot for Trans ect C generated by model over one tidal cycle. .......48 4-1 Approximate boundaries of eastern and western zones for sand budget analysis. ............59 4-2 Volumetric rate components char acterizing sand budget for eastern zone. .......................59 4-3 Length of north beach selected for FDEP budgets. ...........................................................60 4-4 Length of south beach selected for JID budget. .................................................................60 4-5 Combined JID trap and ICWW annual dr edged volume against year of placement. ........61 4-6 Components of eastern zone sand budget for 1952-88 ......................................................61 4-7 Components of eastern zone FDEP sand budget for 1974-1986. ......................................62 4-8 Components of eastern zone FDEP sand budget for 1986-2002. ......................................62 4-9 Components of eastern zone JID sand budget for 1993-1998. ..........................................63 4-10 Components of eastern zone JID sand budget for 1998-2006. ..........................................63 10

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4-11 Components of sand budget for the western zone. ............................................................64 4-12 Volumetric sand transport rates in the western zone. ........................................................64 A-1 Measured time-series of significant wave height off Melbourne Beach in 8 m depth. .....75 A-2 Joint probability density for wave height and frequenc y in 8 m, showing typical wave height of around 0.6 m and fre quency of 0.15Hz (7 s wave period). .......................75 A-3 Cumulative probability that significant wave height will be less than a given value at depth 3 m. ...........................................................................................................................77 A-4 Cumulative probability that Shields parame ter will be less than a given value for combined wave-current flow; (b) Some bed load transport, rippled bed (c) bed load and some suspended load, rippled bed; (d) Strong bed load and suspended load, sheet flow. The category of no sediment motion is to the left of dashed line in category (b). ...78 A-5 Cumulative probability that Shields sedime nt mobility parameter will be less than a given value for pure tidal current flow Labels are identical to Figure A.4. ......................79 A-6 Gross sediment mobilization time-s eries for 2003-2005 at Jupiter Inlet mouth. ...............79 B-1 JID Beach profiles at R-13.................................................................................................80 B-2 JID Beach profiles at R-14.................................................................................................81 B-3 JID Beach profiles at R-15.................................................................................................81 B-4 JID Beach profiles at R-16.................................................................................................82 B-5 JID Beach profiles at R-17.................................................................................................83 B-6 County beach profiles at R-13. ..........................................................................................84 B-7 County beach profiles at R-14. ..........................................................................................85 B-8 County beach profiles at R-15. ..........................................................................................86 B-9 County beach profiles at R-16. ..........................................................................................87 B-10 County beach profiles at R-17. ..........................................................................................87 B-11 Shoreline changes for 1993-2006 (R-13 to R-17). .............................................................88 B-12 Unit volume changes for 1993-2006 (R-13 to R-17). ........................................................88 B-13 Shoreline position at monume nt R-13 starting February, 1993. ........................................89 B-14 Shoreline position at monume nt R-14 starting February, 1993. ........................................89 11

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B-15 Shoreline position at monume nt R-15 starting February, 1993. ........................................90 B-16 Shoreline position at monume nt R-16 starting February, 1993. ........................................90 B-17 Shoreline position at monume nt R-17 starting February, 1993. ........................................91 C-1 Shoreline on November 30, 2004 (10:10 am). ...................................................................93 C-2 Shoreline on April 07, 2006 (1:15 pm). .............................................................................93 C-3 Beach imaging control points north of camera. .................................................................94 C-4 Beach imaging control points south of camera. .................................................................94 C-5 Comparison between shoreline positions in 2004 and 2006. .............................................96 C-6 Tide on November 30, 2004 corresponding to Figure C.1 (2.25 ft above MLLW). .........96 C-7 Tide on April 7, 2006 corresponding to Figure C.2 (0.5 ft above MLLW). ......................97 D-1 Simple model-based results of progression of erosion and accretion as a result of a shore-normal structure. ......................................................................................................99 D-2 Jupiter Inlet with south jetty extens ion segments A (linear) and B (curved). ..................101 D-3 Inlet flow patterns for existing cond ition and a modification (flood and ebb). ...............102 D-4 A qualitative assessment of no-inlet shoreline. ................................................................103 D-5 Bakers Haulover Inlet. ....................................................................................................104 12

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LIST OF SYMBOLS A Linear segment of jetty Angle between u and v components of velocity B Curved segment of jetty; backscatter intensity b Channel width C Sediment concentration C d Sediment concentration predicted from model C g Shoreward component of wave group velocity C s Sediment concentration observed through sampling d Grain diameter d 25 Diameter corresponding to 25% of sample d 50 Median diameter d 75 Diameter corresponding to 75% of sample d Breaking induced dissipation E Wave energy g Gravitational acceleration Fluid density Shields parameter Q Gross sediment mobilization rate Q net Net littoral drift southward Q s Volumetric rate of sand fl owing southward bypassing the inlet Q i Volumetric rate of sand entering the inlet Q is Volumetric rate of sand leavi ng the channel and flowing southward Q l Volumetric rate of sediment lost offshore 13

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Q st Volumetric rate of sediment flowing southward from the inlet Q ic Volumetric rate of sa nd flowing into northern ICWW Q c Volumetric rate of sand fl owing to the Central Embayment Q nw Volume rate of sediment flowing into the Central Embayment from the North West Fork Q n Volume rate of sediment flowing into the Central Embayment from the North Fork Q f Volume rate of sediment flowing into the Central embayment across the FECRR bridge Q sw Volume rate of sediment flowing into the Central Embayment from the South West Fork S Specific Gravity u Velocity in east-west direction U Resultant velocity v Velocity in north-south direction V ud Beach volume change rate updrift of inlet V dd Beach volume change rate downdrift of inlet V st Volumetric rate of sand accumulation in the trap V ic Volumetric rate of sand accumulation in the ICWW channel V c Volumetric rate of accumu lation in the Central Embayment Bed shear stress 14

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Abstract of Thesis Presen ted to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science SAND TRANSPORT RATES AT JUPITER INLET, FLORIDA By Shirshant Sharma May 2007 Chair: Ashish J. Mehta Major: Civil Engineering At Jupiter Inlet on the east coast of Florida, sand bypassing by hydraulic dredging has been used to maintain the navigation channel and nourish the downdrift beach. The basis for this procedure is a sand budget devel oped nearly two decades ago. The objective of the present study was to revisit the budget, and to assess the e fficiency of the bypassing procedure. Based on an analysis of available and newly collec ted data, rates of sand transport and accumulation/depletion have been examined for the inlet and its central embayment. The peak flood flow velocity was found to be approximately 35% greater than the ebb flow velocity, which as a result caused more sediment to flow into th e channel than out of it. This observation is supported by calculations of bed shear stresses from the velocity measurements. The increase in the frequency of dredging in th e sand trap has resulted in a slight decrease in the volume of sand deposition in the ICWW rela tive to the JID trap. Th e 8 km long stretch of the beach north of the inlet has remained st able since 1974. Unit and total volume changes for the 1.2 km length of the beach south of the inlet reflect the difficulty inherent in choosing any particular period as being re presentative of a mean budget fo r the beach. In the 1993-1998 and the 1998-2004 periods, volume change rates were positive, indicating annual accretion. When the post-jetty reconstruction pe riod was changed to 1998-2006, substantial rates of loss of sand 15

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were found. These losses imply increased effect of wave activity on the er osion potential of the beach. An inference one can draw from these obs ervations is that inlet sand budget must be examined each year based on data from the previous year to track the perfor mance of the inlet. In order to increase the accuracy of future sediment budget analyses, beach profiles should be obtained over shorter spatial intervals than at present. The movement of sand in the western half of the Central Embayment is low because of low flow velocities. However, sand does move in to the embayment at its eastern end under the FECRR bridge, at the rate of about 1,200 m 3 /yr. 16

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CHAPTER 1 INTRODUCTION 1.1 Problem Statement Tidal inlets provide naviga tional access from the sea to bays for commercial and recreational purposes, and also a llow for the necessary exchange of waters for maintaining bay water quality because the quality of water is poorer landward than in the sea. At sandy inlets, some of the littoral sediment is often trapped in the inlet channel dur ing flood flow, and some sediment is transported offshore during ebb flow The inland and offshore diverted material is therefore not retained as part of the littoral drift, as would occur in the absence of the inlet. Also, this interruption in the littoral sediment transpor t tends to cause recession of shorelines adjacent to the inlet. At many inlets steps have been taken to re duce shoreline recession a nd to keep the inlet channel free from excessive sediment deposition, so that navigation is pos sible. Jupiter Inlet on the Atlantic Coast of southern Florida has also fa ced similar issues in past, and one of the major concerns there has been the erosion of sand from the beach south of the inlet. In 1993 the Jupiter Inlet District (JID), which is the custodian of th e inlets role as a navigation channel, instituted a management plan to maintain the channel and m itigate shoreline erosion by regularly dredging a sand trap within the channel, and pumping the sa nd to the beach south of the inlet. A principal basis of this plan has been the budget of sedi ment in the inlet area, which indicates sand pathways, volumetric rates of sand transport and zones of sand accumulation or loss. A missing component in the budget was the rates of gain or loss of sand along the contiguous shorelines, because comprehensive beach surveys covering a sufficiently long time (years) and distances (several kilometers north and south of the inlet) were not available when the budget was 17

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prepared. The present study was carried out to revisit the sand budget using more extensive and accurate surveys that have since become available. 1.2 Objective and Tasks The objective of this study was to determin e a sand budget for the Jupiter Inlet area, including its inner bay called the Central Emba yment. The tasks undert aken to meet this objective included the following : Collection of current velocity and suspended sediment concentration data for sand moving within the inlet channel. Use of the numerical model EFDC, originally calibrated and validat ed by Alkhalidi (2005), along with collected data to estimate sand load s at selected transect s in the inlet channel and the Central Embayment. Reanalysis of data on beach profiles, sand accu mulation and sand transfer in the inlet area compiled in Odroniec (2006), using addi tional data acquired since that study. Updating the sand budget presente d in Mehta et al. (1991) for the inlet area, and for the Central Embayment based on more recent st udies (Mehta and Ganju, 2003; Patra 2003; Patra and Mehta, 2004; Alkhalidi, 2005) and the present work. 18

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CHAPTER 2 FIELD STUDY 2.1 Site Description Jupiter Inlet has been in existence for over th ree centuries; however, it has been used as a waterway mainly in the past century. The Loxa hatchee River empties into the Atlantic Ocean through this inlet, which is located in north ern Palm Beach County on the southeast coast of Florida. The three main tributaries of the estuar y are the Northwest Fork, the North Fork and the Southwest Fork. In addition, Jones Creek and Sims Creek, which are much smaller tributaries, also feed into the estuary th rough the Southwest Fork. Figures 2-1 and 2-2 show the general location map of the study area. The navigation ch annel (maintained by JID) runs westward from the inlet, under the FECRR (Florida East Co ast Railroad) bridge, and through the Central Embayment approximately 14 km upstream of th e inlet. The navigation channel has a bottom width of about 31 m and is maintained at -1.75 m (referenced to the National Geodetic Vertical Datum 1929, NGVD 29, or -2.21 m with reference to the No rth American Vertical Datum 1988, NAVD 88). Figure 2-3 shows the location of the sand trap. Mainly, coarser se diment is deposited in the trap, and lesser amount of smaller sediment is deposited elsewhere in the channel. The mean diameter of sediment collected in the sand trap is about 0.80 mm. The r eason for the relatively large diameter in the trap is that normally the finer sediment remains in suspension due to the high flow velocities in the channel, and thus does not deposit in the trap. To estimate the rate of trans port of sediment in suspension, data were collected in two different ways, at a fixed poi nt and from a vessel underway. 19

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2.2 Fixed-Point Data Fixed-point data collection involved two methods. One was using an Acoustic Doppler Current Profiler (ADCP), which measured the flow velocity at different heights above the bottom in three mutually perpendicula r directions. Two types of ADCP s were used: (1) a Workhorse WH1200 from RD Instruments, and (2) Aquadopp current profiler from Nortek. The other method involved the use of a Niskin sampling bottle, which collected water samples (for determination of suspended sediment concentratio n) at four elevations above the channel bed. Current measurements using ADCP were carried out twice. The first period was from 10/13/05 to 11/16/05, and the second from 02/16/06 to 03/02/ 06. Data using the Niskin bottle were also collected twice, on 11/17/05 and on 03/01/06 at Station 1 (Figure 2-4) 2.2.1 Data Collection using ADCP ADCPs operate by measuring the reflection of an acoustic signal from particulate matter in water based on the Doppler-shift principle. Wh ile these instruments ar e primarily used to measure the velocity of such particles (and th ereby deduce the speed of current transporting particles), they can also provi de information on the concentration of particulate matter. Conventional ADCPs typically use a Janus confi guration consisting of four acoustic beams, paired in orthogonal planes, where each beam is inclined at a fixed a ngle with the vertical (usually 20-30 o ). The sonar measures the component of velocity projected along the beam axis, averaged over a range-cell, whose along-beam lengt h is roughly half that of the acoustic pulse. This information is measured in the form of the intensity of the received reflection, also referred to as the backscattering strength, backscatter intensity or signal amplitude (measured in decibels) (R.D. Instruments, 1989). The ADCPs used recorded this information in instrument-generated data files. 20

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At the study site each ADCP was installed on a tripod attached to the bottom by three aluminum pipes jetted into the bed. The top of the instrument was 2 m above the bed, approximately 3 m below the mean water level. Figure 2-5 shows the design of the supporting structure. Each ADCP was oriented with respect to the geographic north, so that the velocity could be measured in two components, and the resultant velocity of water flowin g into and out of the channel. The angular difference between the east-we st direction and the axis of the inlet channel at the site was taken as 15 o The ADCPs transmitted a ping from the transducer element. The return echo was received at th e instrument over an extended period, with echoes from shallow depths arriving sooner than the ones from greater depth ranges. Profiles were produced by rangegating the echo signal, i.e., the echo was split into successive segments called depth-bins, which correspond to successively deeper depth ranges. Th e ADCP was configured to give the velocities at 11 elevations. The highest elevation was 1.8 m above the base of the tripod (taken as the nominal bed datum). The spacing between two cons ecutive bins was 0.2 m. All acoustic current profilers have a region immediately in front of the transducers, called the blanking distance, over which no measurements can be made. This region is required for the transducer and electronics to recover from the high-energy transmitted pulse. The blanking distance for the instruments used was 0.2 m. There is also a zone close to th e bed, from where data received are not stored due to their corruption by the presence of the bed. Only the top four elevations (1, 1.2, 1.4 and 1.6 m above datum) were usable because the presence of the supporting stru cture influenced, in a negative way, the acoustic signals from lower elevations. Velocities measured in the nort h-south and east-west dir ections were used to calculate the resultant velocities (vectors) of water into and ou t of the channel. 21

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The first set of current observations was made during the period 10/13/05 to 11/16/05 using both ADCPs, one at each stat ion. The ADCP at Station 1 wa s not in operation at the time sampling using the Niskin bottle was carried out on 11/17/05. Despite this limitation, sampling was done assuming that current data woul d be recorded by the ADCP at Station 2. Unfortunately, that device was recovered damage d due to an undetermined cause. As a result, a second set of sampling with the bottle was ca rried out at Station 1 on 03/01/06, when the ADCP was there in operation. 2.2.2 Analysis of ADCP Data for Station 1 Based on the ADCP data at Station 1, Figure 2-6 shows the variation of velocity at four elevations above the bed (datum). The period co vered is 9.5 hours on 10/13/05, which is also the duration over which water sampling was carried out. In Figures 2-7 and 28, velocity profiles at flood flow and ebb flow, respectively, have been plotted at selected times All profiles follow the log-velocity distribution charac teristic of open channel boundary layer flows. These yield the following values of the friction velocity u and the bed shear stress b (using a density of 1,027 kg/m 3 for seawater) tabulated in Ta ble 2-1. In general, the shea r stresses are higher during flood than ebb, which correlates with the observation of net sand inflow from the Ocean into the inlet channel. 2.2.3 Water Sampling The Niskin bottle is a 0.64 m long plastic tube (with a diameter of approximately 0.12 m) that is lowered into water while open at both ends. Its approximate volume is 2.37 liters. The bottle was mounted in a steel frame, which could be submerged in water by a tethered rope, and when the frame reached the desired depth, wate r could pass freely through the bottle. At that 22

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point both ends were closed by hi nged lids to capture a sample of water at that depth by sending a messenger weight down the rope to which the bottle frame was tethered. During each sampling study, the bottle was used to collect water samples at four elevations above the bed (0.3, 0.6, 0.9 and 1.2 m) at different times. The samples were filtered on site using standard coffee filters, and the se diment collected was stored in zip-lock bags along with the filters. The samples were then oven-dried for 48 hours in the laboratory. Each dried filter with the sediment was weighed in a Mettler balance, and the filter was al so weighed without the sediment, after removing it from the filter. Thus the weight of sediment could be calculated. Sediment concentration was obtai ned by dividing the weight of the sediment by the volume of water of the sample in the bottle. 2.2.4 Analysis of Niskin Bottle Data Sediment flux flowing into or out of the channel was calculated by multiplying the suspended sediment concentration at an eleva tion at a time by the corresponding velocity. Synchronous velocity and concentration values were only available for the elevation of 1.2 m above the channel bed, so the time-series of flux for this elevation only was obtained. Sieve analysis was carried out for the sediment collected on the filters, using sieve sizes of 0.50, 0.25, 0.125 and 0.0625 mm. Table 2-2 gives the d 25 d 50 d 75 percentile diameters and the corresponding sorting coefficient o752(/ Sdd 5) for different times. Based on the well-known MIT classification, the sediment was found to fa ll in the range of fine to medium sand. Figures 2-10 and 2-11 show time-series of suspended sediment concentration (at different elevations) and depth-aver aged velocity, respectively. It is ob served that the concentrations are comparable at all elevations when the velocity is around 0.5 m/s. Howeve r, at peak velocities (0.8-1.0 m/s), concentrations at 0.3 and 0.6 m ar e about 150% of the values at the top two 23

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elevations. This behavior suggest s that at higher velocities, larg er sand particles that otherwise would travel as bed load also came into suspension. The time-series of sediment flux at 1.2 m el evation using synchronous data on velocity and concentration is shown in Figure 2-12. Positive values of flux mean transport into the channel and negative values indicate transport out of the channel. 2.3 Underway Data 2.3.1 Data Collection An Aquadopp ADCP was used to collect the ba ckscatter intensity data underway in the channel (Vik Adams, Coastal and Ocea nographic Engineering Laboratory, personal communication). The device was mounted on th e side of a 5.2 m long McKee boat and was submerged in water to a depth of 0.3 m. A clos ed polygonal path was predefined along which the vessel was navigated. While moving along that path, the vessel crossed the channel three times at three selected transects. Figure 2-13 shows the location of these tr ansects. Backscatter intensity data from the ADCP were analyzed for times onl y when the vessel traversed a transect. From Transect 1 data from 17 differe nt locations along the transect was taken. For Transects 2 and 3, data from 29 different locations were obtained. Backscatter intensity data were collected fo r each transect 21 times Depth profile along each transect (for every one of these 21 sets of observations) was also recorded. Depth between the instrument and the channel bed was subdivide d into 11 depth-bins for the first and second transects, and for the third tr ansect into 7 bins. The spaci ng between two consecutive bin elevations was 0.5 m. 2.3.2 Analysis of Underway Data Water sampling was also done using the Nisk in bottle on 09/05/2006 at one location along the selected path of the vessel. The samples were collected in the same way as explained earlier, 24

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but at two elevations, surface and mid-depth. Sedime nt concentrations were calculated using the procedure given in Section 2.2.3. Concentrations at different elevations we re plotted against the corresponding backscatter intensity values (in decibels) recorded by the ADCP. The regression equation for the best-fit curve was used to calibrate for the concentration from the backscatter intensity values for all observation points. Figu re 2-14 shows the plot between concentration and backscatter intensity values and the best-fit equation. The calibration equation relating the suspended sediment concentration C (kg/m 3 ) with the backscatter intensity B (db) is (2-1) 90.15362x10BCe Where, and 0.1536 are the regression coefficients. 92x10 Contours plots were obtained for concentration and velocity for the three transects. Given u as the velocity in the east-west direction and v in the north-south dir ection, Figure 2-15 shows a plot for u versus v and the angle by which the u had to be rotated to calculate the resultant. Similar plots were obtained for Transects 2 and 3. The resultant velocity U at any position along a transect wa s calculated using the following equation cossin Uuv (2-2) For example: For Transect 1, bin 1, consider u = 0.683 m/s and v = -0.287 m/s. Therefore, (0.683)cos(169)(0.287)sin(169) U 0.3725m/s For illustrative purposes, Figures 2-16 and 2-17 show cross-sectional distribution of the velocity at the time of maximum sediment influx, and outflux, respectively. It was found that the 25

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cross-sectional mean velocity of water flow ing in was approximately 35% higher than the corresponding velocity of water flowing out. Figures 2-18 and 2-19 illustrate distributions of maximum flux (kg/m 2 s) over the cross-section (Transec t 1) for water flowing in and out, respectively. Figure 2-20 shows time-series of cross-sectiona l average suspended sediment flux at each transect. It is observed that a higher cross-sectional mean flux of sediment occurred when water moved into the channel compared to when it moved out. This difference is explained by sediment deposition that takes place inside the channel. Figure 2-1 Location map of the study area (Source: www.live.com ). 26

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Figure 2-2 Jupiter Inlet, Central Embaymen t and tributaries (adapted Google image) Sand trap Figure 2-3 Location of sand trap in Jupite r Inlet channel (adapted Google image). 27

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Figure 2-4 Fixed-point sampling Station 1 (26 56.28 N and 80.68 W) and Station 2 (26.04 N and 80.34 W) (adapted Google image). Figure 2-5 Supporting structure for the ADCP. 28

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-1.5 -1 -0.5 0 0.5 1 1.5 8:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:00 Time (hours)Velocity (m/sec) 1.6m 1.4m 1.2m 1.0m Figure 2-6 Current velocities recorded at four elevations on 03/01/06 at Station 1. Figure 2-7 Velocity profile s at selected times du ring flood flow on 03/01/07. 29

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Figure 2-8 Velocity profiles at sel ected times during ebb flow on 03/01/07. -1 -0.5 0 0.5 1 0 50100150200250300 Time (hours)Velocity (m/sec) Figure 2-9 Depth-averaged result ant velocity recorded between 02/16/06 to 03/02/06 at Station 1. 30

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0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 7:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:00 Time (hours)Conc (kg/m3) At 0.6m At 0.9m At 1.2m At 0.3m Figure 2-10 Suspended sediment concentra tion time-series at Station 1 on 03/01/06. -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 7:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:00 Time (Hours)Velocity (m/sec) Series1 Figure 2-11 Depth-averaged velocity time-series at St ation 1 on 03/01/06. 31

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-0.03 -0.025 -0.02 -0.015 -0.01 -0.005 0 0.005 0.01 7:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:00 Time (hours)Flux (kg/m2sec) Figure 2-12 Suspended sediment flux time-series at 1.2 m elev ation at Station 1 on 03/01/06. Figure 2-13 Three transects for underway data co llection (Courtesy: Professor Arnoldo ValleLevinson). 32

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y = 2E-09e0.1536x0.0000 0.0010 0.0020 0.0030 0.0040 0.0050 0.0060 6065707580859095100 Backscatter Intensity (db)Concentration (kg/m3) Figure 2-14 Calibration curve of sediment concentr ation versus backscatte r intensity at Jupiter Inlet. -200 -150 -100 -50 0 50 100 150 200 -200 -150 -100 -50 0 50 100 150 200 u Figure 2-15 Plot of u versus v and the rotation angle = 169 o to calculate the resultant velocity at Transect 1. Positive values denote flood flow. 33

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Figure 2-16 Velocity distribution at Transect 1 for water flowing in at 8:00 pm on 05/09/06. At that time the incoming suspende d sediment flux was maximum. Figure 2-17 Velocity distribution at Transect 1 for water flowing out at 2:30 pm on 05/09/06. At that time the outgoing suspended sediment flux was maximum. 34

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Figure 2-18 Suspended sediment flux distribution at Transect 1 at 8:00 pm on 05/09/06, when incoming cross-sectional mean flux was at its peak. Figure 2-19 Suspended sediment flux distribution at Transect 1 at 2:30 pm on 05/09/06, when outgoing cross-sectional mean flux was at its peak. 35

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Flux vs Time at three transects -0.001 -0.0005 0 0.0005 0.001 0.0015 0.002 10.000012.000014.000016.000018.000020.000022.000024.0000 Time (hrs)Flux (Kg/m2sec) Transect 2 Transect 3 Transect 1 Figure 2-20 Time-series of cross-sectional averaged flux at three transects based on measurements on 05/09/06. Table 2-1 Shear stress at ebb flow and flood flow Time (hr) Flow stage u (m/s) b (Pa) 8:00 Ebb 0.20 43.0 9:00 Ebb 0.15 23.2 12:00 Flood 0.17 30.9 13:00 Flood 0.26 68.2 14:00 Flood 0.27 75.5 15:00 Flood 0.23 56.0 16:00 Flood 0.20 41.7 18:00 Ebb 0.17 31.1 19:00 Ebb 0.21 44.8 36

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Table 2-2 d 25 d 50 d 75 and S o values for different times on March 01, 2006 Time (hr) d 75 (mm) d 50 (mm) d 25 (mm) S o 8:00 0.100 0.135 0.089 1.05 9:00 0.165 0.120 0.082 1.41 10:00 0.160 0.120 0.082 1.39 11:00 0.120 0.090 0.078 1.24 12:00 0.185 0.155 0.105 1.32 13:00 0.120 0.090 0.078 1.24 14:00 0.120 0.090 0.078 1.24 15:00 0.115 0.089 0.076 1.23 16:00 0.110 0.087 0.075 1.21 17:00 0.100 0.085 0.074 1.16 37

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CHAPTER 3 SEDIMENT LOAD ESTIMATION 3.1 Introduction Environmental Fluid Dynamic Code model se tup for the Central Embayment was carried out by Alkhalidi (2005), who also calibrated and validated the model using sand trap accumulation data for a 30-day period from September 17 to October 16, 2000. The original setup is summarized; details are found in Alkhalidi (2005). In the present study, suitable modifications were made to that setup. These modifications, specifically with respect to the seaward boundary condition for sediment tran sport, are described in this chapter. 3.2 Model Setup The model was setup in the following way: Grid generation for the model was done us ing EFDC-Explorer (a Microsoft Windows based pre-processor and post-processor) devel oped by Craig (2004). To generate the grid, the grid type, cell size, number of water a nd sediment layers, time step, and the topography and domain of the water body were specified th rough input files. Figure 3-1 shows the grid generated by the Explorer. Grid number s were specified in the input file. The initial conditions for the water column (sp ecified in Explorer) in cluded the number of size-classes and the grain size re presenting each size-class, the initial fraction of each sizeclass, bed porosity, and bed bulk density for every cell in the input files. Boundary conditions were assigned using a concentration time-series as expl ained in Section 3.3. The seaward boundary condition at Ju piter Inlet was assigned from underway data collection at Transect 1 as explained in Section 3.3. Suspe nded sediment concentrations were measured along that transect (Chapter 2). The hydrodynamic model calculates the water su rface elevation, velocity, and shear stress (and shear velocity). Then, the m ode of sediment transport (bed load or suspended load) is determined at the center of every cell using th e approach of van Rijn (1984). When the bed shear velocity calculated by the model is less than the critical shear velocity, which is also calculated by the model in the same time-step, no bed erosion takes place and there is no bed load transport. Sediment in suspension under this condition w ill deposit onto the bed. When the bed shear velocity exceeds the critical shear velocity, but is less than the settling velocity calculated by th e model, sediment is eroded and transported as bed load. Sediment in suspension under this condition will deposit onto the bed. When th e bed shear velocity exceeds both the critical shear velocity and th e settling velocity, bed load transport ceases and the eroded sediment is transported as su spended load. Thus, after the model calculates the bed shear velocity, critical shear velocity a nd the settling velocity, it compares the three 38

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quantities and checks for the above three cond itions. After determining the transport mode, the magnitudes of bed load and the suspended load are calculated. The governing equations of the sediment transport model are solved to determine rates of erosion/accumulation, new bed level, and new bed composition. Fina lly, the outputs of th e hydrodynamic and the sediment models are used as initial conditions for the next time-step calculations. The bed roughness coefficient in the model is composed of two components, a fixed component, which was set to 0.02 m everywhere on the model grid, and a variable component that took into account the presence of seagrass. The variable component was set to 0.035 m in the seagrass area (Chow, 1976), and 0 everywhere else. The hydrodynamic boundary conditions at the six boundaries were specified by Alkhalidi (2005) as follows: Boundary (1): Water surface elevation at inlet. Boundary (2): Water surface elevation at south ICWW. Boundary (3): Water surface elevation at north ICWW. Boundary (4): Water discharge at Southwest Fork. Boundary (5): Water discharge at Northwest Fork. Boundary (6): Water discharge at North Fork. The following sediment boundary conditions were specified by Alkhalidi (2005): Boundary (1) at the Jupiter Inlet entrance, as described later. Boundary (5) at the upstream end of the Northwest fork (relationship between discharge and suspended sediment concentration derived from hydrologic data). At boundaries (2), (3), (4) and (6) the susp ended sediment loads were assumed to be negligible. 3.3 Seaward Sediment Boundary Condition Table 3-1 gives the constant concentration va lues initially used by Alkhalidi (2005) at the inlet boundary in different layers, for different part icle sizes. These concentrations were adjusted until an agreement was obtained between the calc ulated and measured dredging volume rates. 39

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In the present study it was found that the sedi ment flux values generated by the model at Station 1 were not compatible with results from water sampling, but were considerably larger. In order to correct for this discrepancy, the seaward boundary condition was specified by using underway data for Transect 1. The new boundary condition was specified as follows: Suspended sediment concentrations at 11 elevations and 17 observation points were selected along Transect 1 (Figure 2-10), which was close to the seaward boundary of the model. Since sampling was done 21 times along Transect 1 from 12:30 pm to 11:00 pm on May 09, 2006, concentration values could be determined 21 times. Contour plots for concentration were then obtained for the cr oss-sectional area cove red by the ADCP. The area was divided into 16 cells of a 4X4 grid. Using the mean concentration for each cell for all 21 repetitions, 16 time-series were obtained. These time-seri es are shown in Figures 32, 3-3, 3-4 and 3-5. Based on these concentration time-series, obtained from the analysis of backscatter data collected at Transect 1, time-averaged concentration values in Table 3-2 were determined. Figure 3-6 plots these values. The time-averaged concentrations for the 16 cell s were used to specify the spatial variation in the concentration relative to (or as a function of) the cross-sectionally averaged concentration across the boundary. That is, the concentration in each cell was specified as a certain percentage of the cr oss-sectionally averaged concen tration. The cross-sectionally averaged concentration was varied as a func tion of the time-deriva tive of the predicted water surface elevations at transect 1 over the model simulation period. The time-varying concentration in each of the 16 was obt ained by multiplying the time-varying crosssectionally averaged concentrations by the respective percentage difference. Although the ADCP did not cover th e entire cross-section at Tr ansect 1 width-wise, due to limitations imposed by the draft of the vessel, th e device did cover approximately 85% of depths in the channel. It should be pointed out that the 16-cell grid was dimensionless, with the thickness of each layer equal to a quarter of the local depth. Acco rdingly, it was assumed that the cross-sectional area covered by the ADCP was considered to be stretched in order to represent the actual channel boundary. It should also be pointed out th at the movement of particles was low near the 40

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banks of the channel because of lower flow ve locities arising from bounda ry friction. Therefore, the error introduced in the total sediment load cal culations due to the absence of sediment data close to the banks was likely to have been small. 3.4 Model Operation The model was set by Alkhalidi (2005) to give the results for the ye ar 2000 from Julian day 243 (August, 30 th 2000) until day 365 (December, 31 st 2000). On the other hand, in the present study, suspended sediment sampling wa s carried out on March 1, 2006. Therefore, a day was selected in the 243-365 Julia n day range of 2000 modeling which had a tidal range similar to that on March 1, 2006. Figures 3-7 and 3-8 show tides for September 30, 2000 and March 1, 2006 at the FECRR bridge inside Jupiter Inlet. Th e model was thus calibrated to yield sediment fluxes for different transects (Figure 3-9) for March 1, 2006 (based on the similarity in tidal conditions between March 1, 2006 and September, 30 2000). The model was run for a 30 day cold-start pe riod, beginning approximately 30 days prior to the desired time of hot-start period. This was necessary because, according to the required procedure, results obtained at the end of the cold -start period are used as the initial condition for the next, hot-start, period. The time-step for the numerical simulation was selected to be 4 s. Table 3-3 gives concentrations obtained from the model and those measured. Also given are percent differences between prediction and meas urement. Errors of this magnitude are not surprising because, as shown in Appendix A, sediment mobility at the inlet is strongly dependent on the waves near the inlet mouth, whose effect was not included in the model. Given the likely variability in concentration introduced from this factor, it was conclude d that concentrations generated by the model could be used in a post-processing program of EFDC to predict sediment fluxes (and loads) across selected transects in the Loxahatchee grid. Figure 3-9 show these transects (C, D, F and H). 41

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3.5 Sediment Loads Suspended and bed loads were generated by the model for every cell and every time step. However, because the model took approximately 30 days to stabilize to give accurate results, values generated over the last tidal cycle were accepted. The model gave sediment mass rates (loads) based on sediment fluxes across each transect with known cross-sectional area. These loads were plotted against time and the net sediment load was calculated using the trapezoidal rule. As an example, Figure 3-10 shows the plot for load versus time for Transect C. From the net load, the annual volumetric rate (m 3 /yr) of sediment transport across the transect was calculated as shown below with an example. For example, the calculations for Transect C are as follows: Net mass rate flowing over one tidal cycle (12 hr) = 0.03546 kg/s. Total sediment flowing into the embayment over one tidal cycle = 3,063 kg. Assume the wet bulk density of sand = 1,920 kg/m 3 Annual volumetric rate of sediment into the embayment = 1,164 m 3 /yr. In the above example, positive sign indicates sediment transported into the Central Embayment. The volumetric rates of sediment transport across the four transects are given in Table 3-4. Sediment mass rates for Transects D, F and H were found to be negligible. 42

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Figure 3-1 Loxahatchee estuary in Cartesian grid with six flow boundaries and seagrass (green areas). 0.00E+00 2.00E-04 4.00E-04 6.00E-04 8.00E-04 1.00E-03 1.20E-03 10.000012.000014.000016.000018.000020.000022.0000 Time (hrs.)Concentration (kg/m3) Column 1 Cell 1 Column 1 Cell 2 Column 1 Cell 3 Column 1 Cell 4 Figure 3-2 Concentration time-series for cells in column 1 (south end of Transect 1) at the seaward boundary on 05/09/06. 43

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0.00E+00 2.00E-04 4.00E-04 6.00E-04 8.00E-04 1.00E-03 1.20E-03 1.40E-03 1.60E-03 1.80E-03 2.00E-03 10.000012.000014.000016.000018.000020.000022.0000 Time (hrs.)Concentration (kg/m3) Column 2 Cell 1 Column 2 Cell 2 Column 2 Cell 3 Column 2 Cell 4 Figure 3-3 Concentration time-series for cells in column 2 at the seaward boundary on 05/09/06. 44

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-2.00E-03 0.00E+00 2.00E-03 4.00E-03 6.00E-03 8.00E-03 1.00E-02 1.20E-02 1.40E-02 10.000012.000014.000016.000018.000020.000022.0000 Time (hrs.)Concentration (kg/m3) Column 3 Cell 1 Column 3 Cell 2 Column 3 Cell 3 Column 3 Cell 4 Figure 3-4 Concentration time-series for cells in column 3 at the seaward boundary 05/09/06. 45

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-2.00E-03 0.00E+00 2.00E-03 4.00E-03 6.00E-03 8.00E-03 1.00E-02 1.20E-02 1.40E-02 10.000012.000014.000016.000018.000020.000022.0000 Time (hrs.)Concentration (kg/m3) Column 4 Cell 1 Column 4 Cell 2 Column 4 Cell 3 Column 4 Cell 4 Figure 3-5 Concentration time-series for cells in column 4 (north end of transect 1) at the seaward boundary on 05/09/06. Figure 3-6 Contour plot of time-averaged con centrations used to specify seaward boundary condition. Color scale represents concentrati on in mg/L. Depth and width of grid are dimensionless. 46

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Figure 3-7 Tidal plot for September 29 September 30, 2000 at FECRR bridge (Source: www.mobilegeographics.com ). Figure 3-8 Tidal plot for February 28 March 1, 2006 at FECRR bridge (Source: www.mobilegeographics.com ). 47

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Figure 3-9 Transects C, D, F and H where sedime nt fluxes and loads were calculated. Color scale represents depth in meters. -1 -0.5 0 0.5 1 1.5 2 273.4273.5273.6273.7273.8273.9274274.1 Time (Days)Mass Rate (kg/sec) Figure 3-10 Total load versus time plot for Tran sect C generated by model over one tidal cycle. 48

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Table 3-1 Concentrations and grain sizes ( d ) used by Alkhalidi (2005) as inlet boundary condition in the 16 boundary cells. Sediment concentration (mg/L) Layer 0.188 d mm 0.375 d mm 0.750 d mm 1 7.50 5.40 0.10 2 2.27 0.50 0.00 3 0.80 0.07 0.00 4 0.12 0.01 0.00 Table 3-2 Time-averaged concentrations for seaward boundary condition in kg/m 3 Layer no. Column 1 (South side) Column 2 Column 3 Column 4 (North side) 1 0.00040 0.00070 0.00065 0.00150 2 0.00040 0.00050 0.00080 0.00180 3 0.00045 0.00050 0.00110 0.00210 4 0.00048 0.00053 0.00180 0.00250 Table 3-3 Results from model compared with sampling data of March 1, 2006 Time (am) Concentration( C p ) predicted from model (kg/m 3 ) Concentration ( C s ) observed through sampling (kg/m 3 ) Percent difference ( C s C p )/C p X100 7:55 0.178 0.139 -22 8:02 0.133 0.141 6 8:10 0.116 0.144 24 8:34 0.105 0.151 43 8:41 0.089 0.153 71 8:46 0.095 0.154 63 8:54 0.102 0.156 53 9:00 0.278 0.158 -43 9:08 0.123 0.161 31 9:14 0.295 0.162 -45 9:20 0.105 0.164 57 9:26 0.088 0.166 88 9:32 0.621 0.168 -73 9:40 0.093 0.170 83 9:47 0.120 0.172 43 49

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Table 3-3 Continued Time (am) Concentration( C p ) predicted from model (kg/m 3 ) Concentration ( C s ) observed through sampling (kg/m 3 ) Percent difference ( C s C p )/C p X100 10:00 0.133 0.176 32 10:04 0.122 0.177 45 10:06 0.555 0.178 -68 10:11 0.103 0.179 74 10:42 0.135 0.188 39 10:46 0.131 0.189 44 10:53 0.242 0.191 -21 10:57 0.157 0.193 23 11:03 0.126 0.194 54 11:10 0.153 0.196 28 11:14 0.114 0.197 73 11:21 0.120 0.120 66 11:30 0.110 0.202 83 11:34 0.164 0.203 24 11:41 0.148 0.205 39 11:49 0.127 0.208 64 12:00 0.110 0.211 92 12:04 0.113 0.212 88 12:12 0.124 0.214 73 12:16 0.120 0.216 79 12:27 0.133 0.219 65 12:32 0.130 0.220 69 12:38 0.130 0.222 71 12:46 0.144 0.224 56 13:30 0.180 0.237 32 13:32 0.175 0.238 36 13:39 0.139 0.240 73 13:45 0.163 0.242 48 14:00 0.159 0.246 55 14:03 0.182 0.247 36 14:06 0.192 0.248 29 14:13 0.144 0.250 73 14:30 0.131 0.255 94 14:32 0.137 0.256 86 14:36 0.467 0.257 -45 14:40 0.192 0.258 34 15:00 0.170 0.264 55 15:02 0.162 0.264 63 15:05 0.179 0.265 48 50

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Table 3-3 Continued Time (am) Concentration( C p ) predicted from model (kg/m 3 ) Concentration ( C s ) observed through sampling (kg/m 3 ) Percent difference ( C s C p )/C p X100 15:32 0.222 0.273 23 15:35 0.199 0.274 38 15:39 0.239 0.275 15 15:42 0.228 0.276 21 16:00 0.210 0.281 34 16:02 0.206 0.282 37 16:10 0.273 0.284 4 16:10 0.186 0.284 53 16:29 0.120 0.290 45 16:31 0.240 0.290 21 16:35 0.237 0.292 23 16:39 0.202 0.293 45 17:00 0.194 0.299 54 17:02 0.247 0.299 21 17:06 0.169 0.301 78 17:09 0.182 0.302 66 17:30 0.212 0.308 45 17:33 0.224 0.309 38 17:34 0.216 0.309 43 17:38 0.252 0.310 23 17:58 0.222 0.316 42 18:00 0.231 0.316 37 18:02 0.206 0.317 54 18:05 0.185 0.318 72 Table 3-4 Volumetric rates of sand transport in Central Embayment Transects Volumetric rate of suspended load moving into Central Embayment (m 3 /yr) Volumetric rate of bed load moving into Central Embayment (m 3 /yr) Net volumetric rate of sand moving into Central Embayment (m 3 /yr) C 2092 -927 a 1164 D 0 0 0 F 0 4 4 H 0 0 0 a positive sign indicates sediment transported landward. 51

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CHAPTER 4 SAND BUDGETS 4.1 Introduction In this chapter, sand budgets are presented fo r Jupiter Inlet and the Central Embayment. The estuary is conveniently divided into an eas tern zone, which include s Jupiter Inlet, and a western zone consisting of the Central Emba yment. Figure 4-1 shows the two zones. The (volumetric) transport rate components of each budget account for sediment loads entering, depositing within, and l eaving, the two zones. 4.2 Sand Budget for Eastern Zone Volumetric rate components characterizing sand budget for the eastern zone are indicated in Figure 4-2. Table 4-1 gives the definitions of these quantities. The rate components in Table 4-1 were obtained as follows: Sand accumulation rates V ud and V dd were calculated with algorithms used in Rodriguez and Dean (2005). Beach profiles measured along different transects were used as input files, and beach volume changes per meter of shoreline (m 3 /m) between two consecutive survey periods were calculated. From these qua ntities, the volumetric rate of change per year for the selected beach segment was obtained by multiplying the mean volume change per meter by the beach length, and dividing the quantity thus obtained by the period between the surveys (in years). These calcula tions were repeated for every consecutive survey interval, and from it, mean annual rates (m 3 /yr) for each selected long-term intervals were determined. The same long-term intervals were also used in estimating the following rate components: Accumulation rates V st and V ic which were taken from data supplied by the Jupiter Inlet District. The net littoral drift moving south was assumed to be constant based on a previous study on Jupiter Inlet by Mehta et al. (1991). Transport rate Q s which was obtained by subtracting from Q net the rate of sand entering the channel Q i and sand lost to the Ocean Q l The rate of sand entering the inlet Q i was calculated by adding the rate of sand accumulated in the trap V st the rate of sand accumulated in the ICWW V ic the rate of sand transport to the northern and southern reaches of the ICWW Q ic and the rate of sand transported to the Central Embayment Q c 52

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The rate of sand transported sout hward after leaving the channel Q is was assumed to be 8.3% of the sediment entering the channel, Q i based on estimation by Mehta et al. (1991). This percent was determined in that report from sand transport studies before the south jetty was extended seaward in 1998. The present percent is likely to be somewhat lower than the pre-jetty-extension estimat e. However, the difference is unknown. The rate of sand lost to the Ocean Q l was also assumed to be 3.8% of sand entering the inlet Q i (Mehta et al., 1991). This percent was determined from estimates of ebb delta volume changes prior to 1991. Surveys of th e offshore region for years 2000 and 2001 mentioned in Chapter 2, when carried out over a longer time period, e.g., 5 years if done annually, should enable a reassessment of Q l Pre-2000 data are not systematic in terms of survey region covered, and are of poor quality for deciding if the 3.8% value has changed since 1991. Sand transport rate to the ICWW channel north of inlet Q ic was taken from the report of Patra and Mehta (2004). Sand transport rate towards the Central Embayment Q c was also taken from the report of Patra and Mehta (2004). Since Q ic and Q c are small relative to the littoral drift, they have not been evaluated since the rough estimates re ported in Mehta et al. (1991), and employed by Patra and Mehta (2004). However, compilatio n of dredging history in the ICWW by the U.S. Army Corps of Engineers (Freda Zifteh, Jacksonville District, personal communication, December 20, 2006) makes it feasible to revisit these rates, especially because they can be used to obtain realistic boundary conditions at the north and south junctions of ICWW and the Loxahatchee estuary. In the present analysis, sediment loads at these junctions were taken to be nil. 4.3 Data Sources 4.3.1 Types of Data The following two types of data were used to develop the sand budget: Shoreline data, and Beach nourishment and dredging data. These data are described below. 4.3.1.1 Shoreline data Beach profiles used to calculate shoreline and beach volume changes were obtained from the Bureau of Beaches and Coastal Systems of FDEP, Palm Beach County website and from JID. For the selected 30-year long-term period (1975 -2004), there were three FDEP surveys each, for 53

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Martin and Palm Beach Counties. Unfortuna tely, matching FDEP survey dates were not available for the two counties. Surveys found to be closest in dates were a 1976 survey for Martin County and 1974 for Palm Beach Count y, 1982 for Martin County and 1990 for Palm Beach County, and 2002 for Martin County and 2001 for Palm Beach County (Odroniec, 2006). Table 4-2 lists the survey dates for each county as well as the beach profil e type for each survey. A beach profile is considered wading if its offshore length is limited by the distance to which the surveyor can wade or swim, which is typically up to a depth of about 1.5 m. In contrast, a long profile is taken by a survey vess el and is typically longe r than the distance at which the depth of closure occu rs. In the present study, long prof iles were used for calculating updrift and downdrift beach volume changes, which in turn were used to obtain average beach volume changes for the long-term period 1974-1986 and for 1986-2002. The FDEP surveys were based on the NGVD29 tidal datum, whereas the JID surveys were based on NAVD88. The FDEP survey data were converted to NAV D88 by subtracting 0.46 m from the reported elevations. The step-by-step calculation procedure was as follows: Beach profile data files included northing, easting (state-plane coordinates) and elevation (with respect to MLLW, which is 0.8 m be low NAVD 88). From these data, each long profile was represented as distance from the monument and depth at that point. At each monument, the area between two cons ecutive profiles was calculated. This area gave the unit volume change at that monument between two consecutive surveys. Volume change calculations began at closest shorelin e point for all the surveys and ended at the depth of closure estimated to be 3.1m by Odroniec (2006). The unit volume changes were averaged over th e length of the beach to obtain the mean volume change for that beach. The beach segment north of the inlet covered approximately 8 km from the inlet up to monument R-112 in Martin County, and the segment south of the inlet covered approximately 7 km from the inlet up to R-36 in Palm Beach County. The choice of R-112 was based on two cr iteria: (1) at that profile th ere is a slight reorientation of the shoreline of Jupiter Island such that the shoreline between the inlet and that point forms a single stretch of a somewhat straight beach; and (2) most of beach nourishment north of the inlet is believed to have taken place north of R-112. Nourishment dates and 54

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volumes are given in Table 4-3. The choice of R-36 was based on separating the stretch of beach nourishment by JID, which is north of R-36, and by the Palm Beach County, which is south. The volume change for the length of beach wa s divided by the time in years between two consecutive surveys to obtain beach vol ume change per year (Table 4-4). The JID profiles (taken by Lidberg Land Surveyi ng of Jupiter, Florida), were mainly south of the inlet, up to R-21 in Palm Beach County. Mo st profiles began at R13 and ended at R-17, a distance of 1.21 km. As a result, the effect of nourishment down to R-36 could not be determined using these data. The nine surveys are in dicated in Table 4-5. Profile data for February 1993 and March 1994 were provided as blue -printed sheets, and those for the period May 1995 to April 2004 were in the digital format. The blue -printed data were digitized manually. Figures 4-3 and 4-4 show the along-beach ex tents for which the beach volume changes were calculated for the FDEP and JID budgets, respectively. 4.3.1.2 Beach nourishment Sediment dredged from the JID trap be tween 1952 and 2006 has been placed as nourishment on the downdrift beach. Volumes of sand dredged from the trap (including adjacent channel east of the trap) and the ICWW, and the volumetric amount placed as nourishment are given in Table 4-6. The combined JID trap and ICWW annu al volume is plotted against year in Figure 4-5. The mean volume is 46,170 m 3 /yr, and the standard deviation is 47,270 m 3 /yr, indicating significant variabi lity in placed quantities. 4.4 Sand Budget Analysis The first inlet sand budget, for the 1952-88 peri od, is reported in Mehta et al. (1991). Components of that budget are given in Table 4-7, and shown pictorially in Figure 4-6. The budget was based on nourishment volumes from th e trap and the ICWW, without knowledge of synchronous beach volume changes, as beach profiling began only in 1974. 55

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Based on data presented in Tables 4-8, 4-9, 4-10 and 4-11, budgets for four time periods, two using the FDEP surveys from 1974 to 1986 and from 1986 to 2002, and two using the JID surveys from 1993 to 1998 and 1998 to 2006 were deve loped. Since the extens ion of south jetty was completed in 1998 (Michael Grella, JID, personal communication) the budget for the 19982006 period can be expected to in clude effects of the jetty. Figures 4-7, 4-8, 4-9 and 4-10 pictorially show the budgets for the years 1974-1986 (FDEP data), 1987-2002 (FDEP data) a nd 1993-1998 (JID data) and 1998-2006 (JID data), respectively. As an example, steps are given below for the way in which each component of the budget for 1974-86 was determined in the following way: Q net was taken to be 176,000 m 3 per year based on Mehta et al. (1991). Q i = V ic + V st + Q ic + Q c = 56,000 m 3 /yr. Q l = 3.8Q net = 7,000 m 3 /yr. Q s = 176000-56000-7000=113,000 m 3 /yr Q is = 0.083 Q i = 5,000 m 3 /yr. V ic = 21,000 m 3 /yr is the average value for th e period 1974-1986, from Table 4-7. V st = 32,000 m 3 /yr is the average value for th e period 1974-1986, from Table 4-6. Q ic = 2,000 m 3 /yr from Patra and Mehta (2004). Q c = 1,000 m 3 /yr from Chapter 3 (rounded to the nearest thousand m 3 ). The 1974-1986 and the 1993-1998 budgets correspond to the periods before the jetty reconstruction, whereas the 1986-2002 budget cove rs both preand post-jetty construction periods. Finally, the1998-2006 budget solely incl udes the period after reconstruction. Beach volume accretion rates in the 1974-1986 and 1986-2002 budgets are identical; being 1,000 m 3 /yr for the north beach, and 7,000 m 3 /yr for the south beach. Also, the rate of sand entering the inlet remained nearly constant (45,000 m 3 /yr for 1974-1986) and (47,000 m 3 /yr for 1986-2002). There 56

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was a slight decrease in the rate of sand accumu lation in ICWW relative to the JID trap, as seen in Table 4-12. It is uncertain if any statistical si gnificance can be attached to this change. If so, the cause may be attributed to a steady improvement in inlet management practices (Grella, 1993). Volume change data for the 1.2 km length of th e beach south of the in let are given in Table 4-13. The unit volume change and total volume cha nge values reflect the difficulty inherent in choosing any particular period as being representative of a mean budget for the beach. For instance, in the 1993-1998 and the 1998-2004 peri ods the unit volume change and the total volume change are both positive, indicating annual accretion. The pre-jetty period is limited to 1993 as the earliest date when JID surveys were fi rst made. If the post-jetty reconstruction period is increased by two years to 1998-2006, substantia l rates of loss of sand are found. Given the gains during ~5 year long 1993-1998 period and th e nearly equal 1998-2004 period, these losses must be attributed to increased wave activity al ong the beach of such nature as to cause sand loss. Since no long term wave gage data in the proximity of the inlet ar e available prior to 2006, one must tentatively attribute sa nd loss to the severity of wave activity in the region since 2004, which was marked by unusually significant sea st orms during Summer and Fall. An inference one can draw is that sand budgets must be exam ined each year based on data from the previous year to track the performance of the inlet. As far as JIDs management plan is concerned, it would appear that the only nece ssary action should be to maintain the navigable depth and place the sand on the beach, with minimal losses of sand to the interior region, whic h is discussed next. 4.5 Sand Budget for Western Zone Figure 4-11 identifies different components of the budgets for the western zone, which are given in Table 4-14. The components of the budget are calculated in the following way: 57

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Volumetric rate of sand flowing into th e Central Embayment from the NW Fork ( Q NW ) is obtained for Transect F, Table 3-4. Volumetric rate of sand flowing into th e Central Embayment from the SW Fork ( Q SW ) is obtained for Transect H, Table 3-4. Volumetric rate of sand flowing into the Central Embayment from the North Fork ( Q N ), is obtained for Transect D, Table 3-4. Volumetric rate of sand flowing out of th e Central Embayment flowing across the FECRR bridge ( Q F ) is obtained for Transect C, Table 3-4. An analysis of the sa nd movement in the western zone was also done by Patra and Mehta (2004). There, the main accumulation feature is the sandy flood shoal. Generally, a flood shoal develops when an inlet is opened and sediment be gins to enter the bay. The effective date of opening of Jupiter Inlet is 1947, when it was wi dened permanently by dredging and stabilized with jetties (Patra and Mehta, 2004). Carr de Betts (1999) estimated the shoal volume in the Central Embayment to be 7.55x10 5 m 3 in 1983. Much of this volume is believed to have arrived from the Ocean when the inlet was opened initia lly, and after the construction of C-18 Canal in 1957/58, a major portion is believed to have co me soon thereafter from the SW Fork. The present rate of accumulation in the Central Embaym ent was estimated to be of the order of 3,000 m 3 /yr (Patra and Mehta, 2004). The pr esent rate of trans port of sand from the eastern end of the bay (FECRR bridge) is about 1,200 m 3 /yr (Chapter 3). The difference, 1,800 m 3 /yr, arrives from the NW Fork during river floods (which were not modeled in the present study). Figure 4-12 shows the components of budget for the western zone During normal, non-flood conditions, sand load contribution from the NW Fork is negligible (Chapter 3). The North Fork and the SW Fork do not contribute sand to the embayment. 58

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Western z Eastern zone one Figure 4-1 Approximate boundaries of eastern and western zones for sand budget analysis. Figure 4-2 Volumetric rate components characterizing sa nd budget for eastern zone. 59

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Selected length of beach for FDEP surveys Figure 4-3 Length of north beach selected for FDEP budgets. Selected length of beach for JID surveys Figure 4-4 Length of south beach selected for JID budget. 60

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Figure 4-5 Combined JID trap and ICWW annual dredged volume against year of placement. Figure 4-6 Components of eastern zone sand budget for 1952-88 (based on Mehta et al., 1991). 61

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Figure 4-7 Components of eastern zone FDEP sand budget for 1974-1986. Figure 4-8 Components of eastern zone FDEP sand budget for 1986-2002. 62

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Figure 4-9 Components of eastern zone JID sand budget for 1993-1998. Figure 4-10 Components of eastern zone JID sand budget for 1998-2006. 63

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Figure 4-11 Components of sand budget for the western zone. Figure 4-12 Volumetric sand transp ort rates in the western zone. 64

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Table 4-1 Components of sand budget for the eastern zone Quantity (m 3 /yr) Definition Q net Net littoral drift southward V ud Beach volume change rate updrift of inlet V dd Beach volume change rate downdrift of inlet V st Volumetric rate of sand accumulation in the trap V ic Volumetric rate of sand accumu lation in the ICWW channel Q s Volumetric rate of sand flowi ng southward bypassing the inlet Q i Volumetric rate of sand entering the inlet Q is Volumetric rate of sand leaving the channel and flowing southward Q l Volumetric rate of sediment lost offshore Q st Volumetric rate of sediment fl owing southward from the inlet Q ic Volumetric rate of sand fl owing into northern ICWW Q c Volumetric rate of sand flow ing to the Central Embayment Table 4-2 FDEP surveys for Martin and Palm Beach Counties County Survey date Profile type 1976 Wading profile every monument; long profile every third monument 1982 Wading profile every monument; long profile every third monument Martin 2002 Wading and long profiles every monument 1974 Wading profile every monument; long profile every third monument 1990 Wading and long profiles every monument Palm Beach 2001 Wading and long profiles every monument Table 4-3 Jupiter Inlet updrift beach nourishment volumes (Odroniec, 2006) Year Nourishment volume (m 3 ) Source of data 1974 741,620 Aubrey and Dekimpe (1988) 1977 366,990 Aubrey and Dekimpe (1988) 1978 649,870 Aubrey and Dekimpe (1988) 1983 108,410 Michael Grella (personal communication, 2006) 1983 764,560 Aubrey and Dekimpe (1988) 1986 116,920 Michael Grella (personal communication, 2006) 1987 1,704,960 Aubrey and Dekimpe (1988) 1995/1996 1,330,330 Beaches and Shores Resource Center 65

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Table 4-4 Volume change rates updri ft and downdrift of Jupiter Inlet Period V ud (m 3 /yr) V dd (m 3 /yr) 1974-1986 6,600 7,00 1986-2002 6,900 1,000 Change + 300 +300 Change % + 4.3 + 30 Table 4-5 JID surveys in Palm Beach County Date Length of survey Original format February 1993 R-13 to R-17 Sheets March 1994 R-13 to R-17 Sheets May 1995 R-13 to R-17 Digital November 1995 R-13 to R-17 Digital March 1996 R-13 to R-17 Digital November 1996 R-13 to R-17 Digital March 1997 R-13 to R-17 Digital March 1998 R-13 to R-17 Digital March 1999 R-13 to R-17 Digital March 2000 R-10 to R-21 Digital May 2001 R-10 to R-21 Digital October 2002 R-10 to R-21 Digital April 2004 R-13 to R-17 Digital August 2005 R-13 to R-17 Digital November 2006 R-13 to R-17 Digital 66

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Table 4-6 Jupiter Inlet trap dredging and placement volumes, 1952-1995 Year Sand trap dredging (m 3 ) ICWW dredging (m 3 ) Nourishment from sand trap and ICWW (m 3 ) Nourishment from other sources (m 3 ) 1952 55070 22920 77990 0 1954 0 45840 45840 0 1956 32090 53480 85570 0 1958 34460 32090 66550 0 1960 34380 34380 68760 0 1962 34380 0 34380 0 1964 93970 0 93970 0 1966 31040 0 31040 0 1968 39810 0 39810 0 1969 0 38580 38580 0 1970 58830 0 58830 0 1972 58450 33460 91910 0 1975 78390 117660 196050 0 1977 71810 0 71810 0 1979 71050 90760 161810 0 1981 57300 0 57300 0 1983 45840 23910 69750 0 1985 58060 0 58060 0 1986 0 17280 17280 0 1987 50040 0 50040 0 1988 52950 66470 119420 0 1990 64940 0 64940 0 1991 43430 0 43430 0 1992 0 106200 106200 0 1993 47000 0 47000 0 1994 54640 0 54640 0 1995 55010 84420 139430 461460 1996 24100 0 24100 0 1998 64940 0 64940 0 2000 42940 27180 70120 0 2001 63340 49530 112870 0 2002 33620 0 33620 477500 2004 45840 84040 129880 0 2005 59590 0 59590 0 2006 53860 0 53860 0 a NA Not available. b Source of additional sand not known. 67

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Table 4-7 Annual sand transport rates near Ju piter Inlet, 1952-1988 (M ehta et al., 1991). Transport from/to Volumetric rate (m 3 /yr) Net southward littoral drift ( Q net ) 176,000 Entering the channel from littoral drift ( Q i ) 46,000 Bar-bypassed around the inlet ( Q s ) 128,000 Volumetric rate of sand accumulation in the ICWW ( V ic ) 10,000 Volumetric rate of sand accumulation in the trap ( V st ) 23,000 Tidally bypassed by entering and then leaving the channel ( Q is ) 4,000 Ejected from the channel to offshore by ebb flow ( Q l ) 5,000 Transported to ICWW channels north of inlet (Q ic ) 3,000 Transported to Central Embayment ( Q c ) 2,000 Table 4-8 Annual sand transport rates in the eastern zone for 1974-1986 FDEP budget. Transport from/to Volumetric rate (m 3 /yr) Net southward littoral drift ( Q net ) 176,000 Entering the channel from littoral drift ( Q i ) 56,000 Bar-bypassed around the inlet ( Q s ) 113,000 Volumetric rate of sand accumulation in the ICWW ( V ic ) 21,000 Volumetric rate of sand accumulation in the trap ( V st ) 32,000 Tidally bypassed by entering and then leaving the channel ( Q is ) 5,000 Ejected from the channel to offshore by ebb flow ( Q l ) 7,000 Transported to ICWW channels north of inlet(Q ic ) 2,000 Transported to central embayment( Q c ) 1,000 Beach volume change rate updrift of inlet ( V ud ) 1,000 Beach volume change rate downdrift of inlet ( V dd ) 7,000 Table 4-9 Annual sand transport rates in the eastern zone for 1986-2002 FDEP budget Transport from/to Volumetric rate (m 3 /yr) Net southward littoral drift ( Q net ) 176,000 Entering the channel from littoral drift ( Q i ) 54,000 Bar-bypassed around the inlet ( Q s ) 115,000 Volumetric rate of sand accumulation in the ICWW ( V ic ) 17,000 Volumetric rate of sand accumulation in the trap ( V st ) 34,000 Tidally bypassed by entering and then leaving the channel ( Q is ) 5,000 Ejected from the channel to offshore by ebb flow ( Q l ) 7,000 Transported to ICWW channels north and south of inlet ( Q ic ) 2,000 Transported to Central Embayment ( Q c ) 1,000 Beach volume change rate updrift of inlet ( V ud ) 1,000 Beach volume change rate downdrift of inlet ( V dd ) 7,000 68

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Table 4-10 Annual sand transport rates in the eastern zone for 1993-1998 JID sand budget Transport from/to Volumetric rate (m 3 /yr) Net southward littoral drift ( Q net ) 176,000 Entering the channel from littoral drift ( Q i ) 58,000 Bar-bypassed around the inlet ( Q s ) 111,000 Volumetric rate of sand accumulation in the ICWW ( V ic ) 14,000 Volumetric rate of sand accumulation in the trap ( V st ) 41,000 Tidally bypassed by entering and then leaving the channel ( Q is ) 5,000 Ejected from the channel to offshore by ebb flow ( Q l ) 7,000 Transported to ICWW channels north and south of inlet( Q ic ) 2,000 Transported to Central Embayment( Q c ) 1,000 Beach volume change rate downdrift of inlet ( V dd ) 4,000 Table 4-11 Annual sand transport rates in the eastern zone for 1998-2006 JID sand budget Transport from/to Volumetric rate (m 3 /yr) Net southward littoral drift ( Q net ) 176,000 Entering the channel from littoral drift ( Q i ) 61,000 Bar-bypassed around the inlet ( Q s ) 107,000 Volumetric rate of sand accumulation in the ICWW ( V ic ) 18,000 Volumetric rate of sand accumulation in the trap ( V st ) 40,000 Tidally bypassed by entering and then leaving the channel ( Q is ) 5,000 Ejected from the channel to offshore by ebb flow ( Q l ) 7,000 Transported to ICWW channels north and south of inlet( Q ic ) 2,000 Transported to Central Embayment( Q c ) 1,000 Beach volume change rate downdrift of inlet ( V dd ) -9,000 Table 4-12 Rates of accumulati on in JID sand trap and ICWW Period Rate of accumulation in JID trap (m 3 /yr) Rate of accumulation in ICWW (m 3 /yr) ICWW rate as a fraction of JID trap rate 1952-1988 27,000 16,000 0.6 1974-1986 32,000 21,000 0.6 1986-2002 34,000 17,000 0.5 69

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Table 4-13 Jetty preand post-extension volume changes on 1.2 km of south beach Period Jetty Status Unit volume change (m 3 /yr m) Total volume change (m 3 ) 1993-1998 Pre-extension +2.92 +17,526 1998-2004 Post-extension, pre-storms +13.16 +126,310 1998-2006 Post-extension, post-storms -7.46 -71,689 Table 4-14 Definitions of components of western zone sediment budget. Component Definition Q NW Volume rate of sediment flowing into the Central Embayment from the North West Fork Q SW Volume rate of sediment flowing into the Central Embayment from the South West Fork Q N Volume rate of sediment flowing into the Central Embayment from the North Fork Q F Volume rate of sediment flowing into the Central embayment across the FECRR bridge. V C Volumetric rate of accumulation in the Central Embayment Table 4-15 Annual mean sand trans port rates in the western zone. Transport from/to or accumulation Volumetric rate (m 3 /yr) From Northwest Fork ( Q NW ) 1,800 From Southwest Fork ( Q SW ) 0 From North Fork ( Q N ) 0 To Central Embayment past FECRR bridge ( Q F ) 1,200 Accumulation in Central Embayment ( V C ) 3,000 70

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CHAPTER 5 SUMMARY AND CONCLUSIONS 5.1 Summary Due to the presence of Jupiter Inlet, the potential for beach erosion has always existed along the downdrift beach, especi ally since the late 1940s wh en the inlet navigation was stabilized by robust jetties and sand dredging from the channel. The management of the sand resources within the inlet area is dependent on rates of sand inflow, outflow and accumulation (or erosion). The objective of this study was to determine a new sand budget for the inlet area, including its inner bay called th e Central Embayment. Tasks undert aken to meet this objective were: (1) collection of current velocity and su spended sediment concentration data for sand moving within the inlet channel, (2) use of a numerical model along with collected data to estimate sand loads at selected transects in the inlet channel and the Central Embayment, (3) analysis of data on beach profiles, sand accumulati on and sand transfer in the inlet area, and (4) development of sand budgets for the inlet and the Cent ral Embayment. 5.2 Conclusions Based on the above mentioned tasks, the following conclusions can be derived: The peak velocity of the wate r that flows in was found to be approximately 35% more than the velocity of water that flows out, which as result causes more sediment to flow in to the channel than out of it. This observation is supported by calculations of bed shear stresses from the velocity measurements, which were higher during flood flow than during the subsequent ebb flow. The majority of sediment supply from the seaw ard end of the inlet is as suspended load. Suspended sediment mobility just offshore of the mouth is dependent on wave-induced bottom stresses (Appendix A), as can be (p artially) verified from the fact that the movement of sand from the beaches increased significantly between 2004 and 2006 due to storm wave activity. The movement of sand in the western half of the Central Embayment is low because of low flow velocities. However, sand does move into the Central Embayment at its eastern end under the FECRR bridge at the rate of about 1,200 m 3 /yr. This value is in order of magnitude agreement with 1,000 m 3 /yr estimated by Patra and Mehta (2004). 71

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The increase in the frequency of dredging in th e sand trap has resulted in a slight decrease in the volume of sand deposition in the ICWW relative to the JID tr ap. The ICWW-to-trap ratio of annual volume dredged decreased from 0.6 during 1974-1986 to 0.5 during 19862002. The 8 km long stretch of the beach north of the inlet has remained stable since 1974, gaining only 1,000 m 3 /yr, a negligible amount during 1974-2002. The south beach, of 7 km length, has gained 7,000 m 3 /yr during the same period. Unit volume change and total volume change va lues for the 1.2 km length of the beach south of the inlet reflect the difficulty inherent in choosing any particular period as being representative of a mean budget for the beach. For instance, in the 1993-1998 and the 1998-2004 periods the unit volume change and th e total volume change are both positive, indicating annual accretion. The pr e-jetty period is limited to 1993 as the earliest date when JID surveys were first made. If the pos t-jetty reconstruction period is increased by two years to 1998-2006, substantial rates of lo ss of sand are found. Gi ven the gains during ~5 year long 1993-1998 period and the nearly equal 1998-2004 period, these losses must be attributed to increased wave activity along the beach of such nature as to cause sand loss. Since no long-term wave gage data in th e proximity of the inlet are available prior to 2006, one must tentatively attribute sand loss to the severity of wave activity in the region since 2004, which was marked by unusually si gnificant sea storms during Summer and Fall. An inference one can draw from the above obs ervations is that in let sand budget must be examined each year based on data from the prev ious year to track th e performance of the inlet. Most of the erosion at the beach in the vici nity of the inlet (FDEP monuments R-13 to R17) appears to be due to the immediate presence of the inlet. For instance, the shoreline at location R-15 has oscillated between 74 m to +63 m during 1993-2006, relative to shoreline position in February, 1993 (Appendix B). The same beach segment is also the immediate beneficiary of nourishment provided by hydraulic transfer of sand from the inlet. 5.3 Recommendations for Further Work In order to increase the accu racy of future sediment budget analyses, the following recommendations should be considered: Beach surveys should cover the R-13 to R-21 reach annually. R-10 through R-12 may be surveyed every three years. Consideration mu st be given to profiling every 500 ft (152 m) between R-14 and R-16, as opposed to the present 1,000 ft (304 m) distance. For applying the technique described in Appe ndix C to assess shoreline changes south of the inlet from aerial images, the trajectory of excursion of the camera must remain 72

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constant, i.e., its setting must not be changed for the time when the observations are being made. 73

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APPENDIX A WAVE-INDUCED SAND MOBILITY A.1 Wave Data Waves combined with a current increase the effective bed shear stress over merely current flow. This may increase sediment mobilization and thus transport into or out of Jupiter Inlet. Thus, an estimation of how frequently waves m obilize sediment at the inlet mouth can provide an indication of their importance in making additi onal sediment available for transport, over and above transport due to tide. This analysis is carried out in the following two parts: Prediction of bed shear stresses fo r specified waves and currents. Estimation of how these stresses affect sand mobilization. For the stress computations, the measured tida l currents were assumed to be applicable to the mouth area. There are no wave gauges in the immediate vicinity of Jupiter Inlet. However, good records are available from the closest nearsh ore gauge at Melbourne Beach. Because waves arriving at Jupiter from the southeast are sheltered somewhat by the Bahamas Bank, the Melbourne Beach record can be expected to indicat e slightly larger wave heights than at Jupiter Inlet. However, the general wave climate along the Melbourne Beach to Jupiter Inlet coast can be considered to be similar, and the Melbourne B each gauge is believed to be a reliable source of wave information for this stretch of the beach. Thus data from this gauge will used it to calculate wave-induced orbital velocities for bed shear stress estimation. To estimate the sediment transport regime from bed shear stress, the well known Shields criterion will be used. Figure A-1 shows measured wave record s from 2003-2005, which includes several hurricane events. The record is almost complete and can be expected to give a good picture of 74

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the overall wave climate. Calculated statistics of wave height and period are shown in Figure A2. These show a moderate wave climate, with most probable wave heights around 0.6 m and 0.15 Hz frequency (7 s period). These values are in agreement with other estimates of wave characteristics on Floridas Atlantic Coast. Wave properties were then transformed from the 8 m depth contour, where measurements were taken, to the representative depth of 3 m at the inlet mouth, taking into account wave shoaling a nd dissipation (Prof. Andrew Kennedy, personal communication). Figure A-1 Measured time-series of significant wave height off Melbourne Beach in 8 m depth. Figure A-2 Joint probability density for wave hei ght and frequency in 8 m, showing typical wave height of around 0.6 m and freque ncy of 0.15Hz (7 s wave period). 75

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A.2 Sediment Movement The Shields parameter is defined as dSgx)1( (A.1) where b is the bed shear stress, g is gravitational acceleration, is the fluid density and S and d are the specific gravity and median diameter d 50 of the sediment, respectively. For low Shields parameters, there is no sediment mobilization (or transport), and the amount of mobilized sediment increases with increasing The bed shear stress will be estimated for combined wavecurrent flows using use the method of Soulsby et al. (1988). In addition to the sediment parameters, this method requires basic wave and current characteristics. To transform measured wave characteristics at 8 m to the 3 m depth near the inlet mouth, a simple one-dimensional model was used g dEC x (A.2) where E is the wave energy, C g is the shoreward component of the wave group velocity and d is the breaking-induced dissipation, calculated using the method of Thornton and Guza (1982). This model was run for all relevant combin ations of wave height and period, using a characteristic bed slope of 0.020. Knowing the frequency of occurrence for each offshore wave condition, the wave climate at 3 m depth was determined as shown in Figure A-3. Note the maximum significant wave height at this depth does not exceed around 1.9 m, as larger offshore waves will break and reduce wave heights to this value. 76

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Figure A-3 Cumulative probability that significant wave height will be less than a given value at depth 3 m. The statistical distribution of wave heights and periods at th is location was then used to estimate the statistical distribution of bed shear stress b over a typical tidal cycle with peak flood flow velocity of 1 m/s using the method of Souls by et al. (1988). This bed shear stress was then used to calculate the statisti cal distribution of Shields para meter using assumed value of suspendable sediment diameter d 50 = 0.2 mm and specific gravity S = 2.65. The Shields parameters were then used to es timate the sediment transport regime using the criteria in Table A-1, and the statistical probabi lities were used to estimate their frequencies of occurrence. As seen in Table A-1 and Figure A4, waves and currents are large enough that there are almost no occasions when sediment is not m obile. Eight percent of the time, there will be minor bed load transport which probably contribute s little to the overall net transport; larger bed load transport with some suspended load is likely around 23% of overall conditions, while there is strong bed load and suspended load the rema inder of the time, around 69%. An examination of Figure A-4 further shows that ve ry high Shields parameters of > 2 are likely 12% of the time, which would further increase sediment mobilization and assist in transporting sediment into the inlet. 77

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Table A-1 Types of sediment transport and freq uency of occurrence at the inlet in 3 m depth Frequency of occurrence Shields parameter Sediment transport behavior WaveCurrent (%) Current Only (%) < 0.05 No sediment motion 0 17 0.05 < < 0.5 Some bed load transport, rippled beds 8 49 0.5 < < 1 Bed load and some suspended load, rippled beds 23 34 > 1 Strong bed load and suspended load, sheet flow 69 0 Figure A-4 Cumulative probability that Shields pa rameter will be less than a given value for combined wave-current flow; (b) Some bed load transport, rippled bed (c) bed load and some suspended load, rippled bed; (d) Strong bed load and suspended load, sheet flow. The category of no sediment motion is to the left of dashed line in category (b). These large bed shear stresses may be compared to the current-only bed shear stresses induced from pure tidal motion. Figure A-5 and Table A-1 show the Shields probability distributions for pure current flow, and may be co mpared to results for combined wave-current motion in Figure A-4. Sediment m obilization decreases dramaticall y, with no occasions of strong sediment mobilization with > 1, and 17% occurrence of no sediment mobilization at all. Thus, sediment transport into the inlet will be incr eased significantly by waves mobilizing sediment at the inlet mouth. This mobilized sediment is likely to be deposited further in the inlet as the wave 78

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climate decreases, e.g., in the sand trap. The gr oss sediment mobilization (Figure. A-6) is obtained using the following equation 13 2((1))..8.().mQSgdd 2b (A.3) where b is the width of the channel. Figure A-5 Cumulative probability that Shields sedi ment mobility parameter will be less than a given value for pure tidal current flow Labels are identical to Figure A-4. Figure A-6 Gross sediment mobilization time -series for 2003-2005 at Jupiter Inlet mouth. 79

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APPENDIX B SHORELINE AND BEACH VOLUME CHANGES This appendix includes shoreline changes a nd beach volume changes obtained from beach profiles at monuments R-13 th rough R-17. Figures B-1 through B-5 covering profiles from February 1993 to March 2006, are based on data provided by JID (and taken by Lidberg Land Surveying of Jupiter, Florida), Figures B-6 through B-10, including profiles from July 2001 to August 2005, were taken from the Palm Beach County website ( http://www.co.palmbeach.fl.us/erm/enhancement/beachreports.asp ). Unit volume changes and the shoreline changes between consecutive surveys are given in Fi gures B-11 and B-12, respectively. Figures B-13 through B-17 show the shoreline position for R-13 through R-17. -14 -12 -10 -8 -6 -4 -2 0 2 4 6 0200400600800100012001400160018002000 Distance (m)Depth (m) Feb-93 Mar-94 May-95 Mar-96 Mar-97 Mar-98 Mar-99 Mar-00 May-01 Oct-02 Apr-04 Aug-05 Nov-06 Figure B-1 JID Beach profiles at R-13. 80

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-15 -10 -5 0 5 10 0200400600800100012001400160018002000 Distance (m)Depth (m) Feb-93 Mar-94 May-95 Mar-96 Mar-97 Mar-98 Mar-99 Mar-00 May-01 Oct-02 Apr-04 Aug-05 Nov-06 Figure B-2 JID Beach profiles at R-14. -15 -10 -5 0 5 10 020040060080010001200140016001800 Distance (m)Depth (m) Feb-93 Mar-94 May-95 Mar-96 Mar-97 Mar-98 Mar-99 Mar-00 May-01 Oct-02 Apr-04 Aug-05 Nov-06 Figure B-3 JID Beach profiles at R-15. 81

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-15 -10 -5 0 5 10 020040060080010001200140016001800 Distance (m)Depth (m) Feb-93 Mar-94 May-95 Mar-96 Mar-97 Mar-98 Mar-99 Mar-00 May-01 Oct-02 Apr-04 Oct-05 Nov-06 Figure B-4 JID Beach profiles at R-16. 82

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-15 -10 -5 0 5 10 0 20040060080010001200140016001800 Distance (m)Depth (m) Feb-93 Mar-94 May-95 Nov-96 Mar-97 Mar-98 May-99 May-00 May-01 Oct-02 Apr-04 Aug-05 Nov-06 Figure B-5 JID Beach profiles at R-17. 83

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-14 -12 -10 -8 -6 -4 -2 0 2 4 6 0200400600800100012001400160018002000 Distance (m)Depth (m) Jul-01 Jul-02 Sept-03 Jul-04 Aug-05 Figure B-6 County beac h profiles at R-13. 84

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-12 -10 -8 -6 -4 -2 0 2 4 6 020040060080010001200140016001800 Distance (m)Depth (m) Jul-01 Jul-02 Sept-03 Jul-04 Aug-05 Figure B-7 County beac h profiles at R-14. 85

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-12 -10 -8 -6 -4 -2 0 2 4 6 8 0 200 400 600 8001000120014001600 Distance (m)Depth (m) Jul-01 Jul-02 Sept-03 Jul-04 Aug-05 Figure B-8 County beac h profiles at R-15. 86

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-14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 020040060080010001200140016001800 Distance (m)Depth (m) Jul-01 Jul-02 Sept-03 Jul-04 Aug-05 Figure B-9 County beac h profiles at R-16. -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 020040060080010001200140016001800 Distance (m)Depth (m) Jul-01 2002 Sept-03 Jul-04 Aug-05 Figure B-10 County beac h profiles at R-17. 87

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Figure B-11 Shoreline change s for 1993-2006 (R-13 to R-17). Figure B-12 Unit volume changes for 1993-2006 (R-13 to R-17). 88

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0 20 40 60 80 100 120 140 160 180 200 Jan-93Jan-94Jan-95Jan-96Jan-97Jan-98Jan-99Jan-00Jan-01Jan-02Jan-03Jan-04Jan-05Jan-06Jan-07 DateDistance from Monument (m) S outh jetty modification R-13 Figure B-13 Shoreline position at m onument R-13 starting February, 1993. 0 20 40 60 80 100 120 140 160 180 200 Jan-93Jan-94Jan-95Jan-96Jan-97Jan-98Jan-99Jan-00Jan-01Jan-02Jan-03Jan-04Jan-05Jan-06Jan-07 DateDistance from Monument (m) S outh jetty modification R-14 Figure B-14 Shoreline position at m onument R-14 starting February, 1993. 89

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0 20 40 60 80 100 120 140 160 180 200 Jan-93Jan-94Jan-95Jan-96Jan-97 Jan-98Jan-99Jan-00Jan-01Jan-02Jan-03Jan-04Jan-05Jan-06Jan-07 DateDistance from Monument (m) S outh jetty modification R-15 Figure B-15 Shoreline position at m onument R-15 starting February, 1993. 0 20 40 60 80 100 120 140 160 180 200 Jan-93Jan-94Jan-95Jan-96Jan-97Jan-98Jan-99Jan-00Jan-01Jan-02Jan-03Jan-04Jan-05Jan-06Jan-07 DateDistance from Monument (m) S outh jetty modification R-16 Figure B-16 Shoreline position at m onument R-16 starting February, 1993. 90

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0 20 40 60 80 100 120 140 160 180 200 Jan-93Jan-94Jan-95Jan-96Jan-97Jan-98Jan-99Jan-00Jan-01Jan-02Jan-03Jan-04Jan-05Jan-06Jan-07 DateDistance from Monument (m) S outh jetty modification R-17 Figure B-17 Shoreline position at m onument R-17 starting February, 1993. 91

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APPENDIX C ESTIMATION OF SHORELINE CHA NGE FROM AERIAL IMAGERY Rectification of aerial photographs involves th e establishment of ground control points that link each image to its corres ponding aerial coverage on a dig ital orthophoto quarter quad (DOQQ), which serves as the base map. Points are chosen on the image that can be matched to points on the DOQQ. Road intersections and other cu ltural features are pr eferred as reference points rather than natural features. However, in many cases cultural features are absent and features such as trees, shrubs, and the edges of water bodies are used. Where possible, points are evenly spaced across the image, with special em phasis on the edges of the image, and on areas near to the shoreline. Thus, for calculating the shoreline changes south of Jupiter Inlet, aerial imagery was used. For an illustration of the method, we will consid er Figures. C-1 and C-2, which show images for November 30, 2004 (10:10 am) and April 07, 2006 (1: 15 pm), respectively, as obtained from a camera mounted on the Ocean Trails condominium south of the inlet. The rectangle marks the area which had control points. Figures C-3 and C-4 are the images showing the control points north and south of the camera, respectively, on th e south beach. Table C-1 gives the coordinates (latitudes and longitudes) and elevation (meters above sea level) for the control points shown pictorially in Figures. C-3 and C-4. After the ground control points we re established near the beac h, two images were rectified using a computer program developed by Prof. Andrew Kennedy. Ten of the points from Figure C-4 were selected for analysis, as rectificati on required at least 8 of the 10 points. After rectification was complete, the image was made semi-transparent and overlain on the DOQQ. Figure C-5 show plots for shoreline changes prepared by comparing the two images. Figures C-6 and C-7 give the tidal data for the two dates when the images were taken. These indicate that the 92

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images were obtained at differe nt stages of tide; the 2004 image was at high tide and the 2006 image at low tide. Given this discrepancy, the s horelines in Figure C-5, both of which have the same orientation, cannot be compared with regard to beach width. Figure C-1 Shoreline on November 30, 2004 (10:10 am). Figure C-2 Shoreline on April 07, 2006 (1:15 pm). 93

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26 27 28 29 1 3 2 Figure C-3 Beach imaging control points north of camera. Figure C-4 Beach imaging control points south of camera. 22 17 18 25 16 19 20 24 10 11 12 13 14 21 23 15 94

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Table C-1 Coordinates and elevations of the control points. Points Latitude Longitude Elevation (m) 1 2656.422593 8004.282727 3.101 2 2656.424095 8004.284790 3.591 3 2656.424352 8004.283473 3.599 4 2656.429943 8004.284474 2.922 5 2656.445124 8004.293226 2.705 6 2656.414737 8004.272036 5.035 7 2656.416346 8004.268788 5.031 8 2656.417721 8004.269640 5.030 9 2656.416361 8004.272451 5.046 10 2656.273841 8004.221734 4.480 11 2656.272311 8004.221251 4.974 12 2656.267373 8004.221245 4.841 13 2656.263371 8004.222644 4.360 14 2656.263723 8004.220953 6.945 15 2656.265210 8004.221443 6.965 16 2656.269529 8004.216125 6.948 17 2656.272940 8004.207913 5.328 18 2656.273786 8004.204519 1.766 19 2656.245712 8004.211376 4.846 20 2656.230963 8004.206619 5.110 21 2656.218549 8004.197241 7.168 22 2656.221408 8004.184580 3.848 23 2656.216380 8004.213872 0.512 24 2656.188789 8004.191339 5.839 25 2656.168808 8004.173882 4.894 26 2656.356848 8004.239158 3.733 27 2656.356970 8004.242266 4.362 28 2656.354013 8004.246407 4.024 29 2656.352355 8004.247356 3.914 30 2656.309336 8004.242825 46.529 95

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Figure C-5 Comparison between sh oreline positions in 2004 and 2006. Figure C-6 Tide on November 30, 2004 correspondi ng to Figure C-1 (2.25 ft above MLLW). 96

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Figure C-7 Tide on April 7, 2006 corresponding to Figure C-2 (0.5 ft above MLLW). 97

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APPENDIX D BASIS FOR THE LENGTH OF SOUTH JETTY EXTENSION D.1 Introduction The purpose of extending the south jetty wa s two-fold: (1) to improve conditions for navigation in the channel, and (2) to increase the retention time of sand placed on the south beach. Improvement in navigation would mean: (a ) streamlining flood and ebb tidal flows, (b) reducing the impact of oblique waves on vessels, and (c) improving the self -cleaning capacity of flow in order to maintain channel depth over the ebb delta. Increase in the retention time of sand was to be achieved by: (a) increasing beach protection from storm waves from th e northwest, (b) reducing the re turn flow of sand into the inlet. For the present study the second purpose is rele vant, as it pertains to the efficacy of the sand placement protocol before and after jetty reconstruction. The placem ent of any structure perpendicular to the shoreline, such as a groin or a jetty, disturbs the littoral sand drift and causes erosion downdrift of the structure. It follows that longer the st ructure the deeper the erosion. There is equivalent accretion on the updrift side. In Figure D-1 the progression of downdrift erosion and updrift accretion are modeled at a shor eline at which a shore-normal structure is placed. The structure and wave c onditions modeled were representative of conditions at Jupiter Inlet. Erosion is seen to exte nd in depth and distance with ye ars. After a very long time and theoretically, the downdrif t shoreline can be expected to recede by a distance equal to the protruding length of the structure. Accordingly, this modeling exercise can be used to show that lengthening the structure will reduced the rate of progression of erosion, but that the depth of erosion will increase. This is an important observa tion as it shows that in the final selection of 98

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the length of the structure, these two aspects of beach erosion (depth versus distance) must be balanced. Two equal-length and parallel je tties at a narrow inlet (such as Jupiter) can be thought of as a single structure impacting the shoreline as in Figure D-1. Once the shoreline is modified by the jetties, the no-inlet shoreline can be theore tically determined by modeling shoreline changes following jetty construction. In practice one can also make a judgmental choice based on the known orientations of the shor elines far from the inlet. -40000 -20000 0 20000 40000 Distance alongshore (ft) 300 200 100 0 -100 -200 -300 Distance offshore (ft) 0 yr 5 yr 10 yr 20 yr 30 yr Infinite time Sand drift 30 yr Figure D-1 Simple model-based results of progression of erosion and accretion as a result of a shore-normal structure. Since the main agent for downdrift shoreline erosion is wave action, in order to reduce the rate of erosion a sheltered area must be created. At Floridas east coast inlets sand drift occurs northward in summer and southward in winter as the wave direction changes from NW to SW. The annual net drift is southward due to the higher energy waves in winter. Nevertheless, because the drift occurs in two directions, downdrift erosion rate can be reduced by extending and reorienting the south jetty. However, erosion cannot be stopped entirely unless other 99

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measures, such as beach nourishment, are taken. Nourishment is essential to maintain the downdrift shoreline in the s hadow zone of the jetty. To revise the configuration of the jetties, tests were carried out in a fixed-bed hydraulic model at the Coastal and Oceanographic Engineeri ng laboratory of the University of Florida. A summary of these tests is given in DelCharco (1992) and results are discussed in Mehta et al. (1992) for an assessment of the downdrift impact of the modified jetties re lative to then existing configurations. This assessment was based on quanti tative criteria relate d a balance between the wave-sheltering effect of the jett ies and their beach erosion potent ial. The longer the jetties, the greater the sheltering effect of the (immediately) downdrift region against severe northeasters. However, this would also mean greater long-term recession of the shoreline. A shelter was desired by JID against episodic er osion immediately downdrift of the inlet. It was feared that flanking of the narrow barrier could take pl ace, i.e., breaching of the barrier island would occur just south of the south jett y. Severe erosion at the site of a parking lot close to the south jetty did occur at the end of October, 1991. D.2 Outcome of Hydraulic Modeling Tests Hydraulic model tests indicate d that any significant extens ion of the north jetty would further divert the net littoral drift away from th e south beach. Therefore, only extensions of the south jetty in various configurations were cons idered. The configuration most likely to succeed was one including a linear extension follo wed by a curved extension (Figure D-2). 100

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0 100 200 ft N Atlantic Ocean Jupiter Inlet A B C L Figure D-2 Jupiter Inlet with south jetty extension segments A (linear) and B (curved). Among the results there were some noteworthy outcomes. One in particular was that a configuration with A = 0 and B = 100 ft would have an overall beneficial effect (reduced wave action in the lee of the jetty and no significant ex tension of erosion downstream). However, tests also showed that A = 0 and B = 200 ft would not be beneficial, as downstream erosion would be high. Similarly, a comparable configuration with A = 100 ft and B = 50 ft (bent more sharply southward) would not be beneficial. While from these three cases the clear conclusion would be that the choice of extension was a 100 ft extension at most, an ex amination of all test results taken together pointed to the likelihood that the outcomes were dependent on the weighting factors used in the chosen criteria for evalua tion. This meant that th e so-called quantitative criteria were in fact somewhat subjective. Als o, limitations inherent in the use of a fixed-bed model to make assessments of the effect of jetty configuration on sand tran sport were felt to be ambiguous. Finally, as shown in Fi gure D-3, the effect of jetty was determined from flow and wave measurements close to the jetty, whereas th e effect of erosion was expected to be over a much longer down stream distance (and not amenable to assessment in a fixed-bed model). In the 101

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final analysis it was decided that the addition of a curved segment would be beneficial, but that an independent approach was required to determine the overall length of the jetty. D.3 Assessment of Jetty based on Shadow Effect Figure D-4 shows the Jupiter Inlet shoreline (which has ge nerally remained stable over the past two decades), with an attempt made to determined the zero line of Figure D-1. The direction of undisturbed littoral drif t would be parallel to this line. On that basis a south jetty extension of A = ~250 ft and B = ~ 150 ft would seems permissible, as even with this extension the south jetty would be in th e shadow of the north jetty with respect to net drift. A prototype case where a signi ficant extension of the south jetty had successfully protected the beach immediately south of the inle t from severe erosion is Bakers Haulover Inlet at the north end of Miami Beach (Figure D-5). The south jetty extension was considerably intrusive with respect to the flow of littoral sand; however, the modification has been successful in eliminating shoreline erosion im mediately downdrift of the jetty. As noted in Mehta et al. (1992), the fi nal length of the south extension was A + B = 175 ft. Figure D-3 Inlet flow patterns for existing c ondition and a modification (flood and ebb). 102

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Net drift Figure D-4 A qualitative assessment of no-inlet shoreline. 103

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Pre-jetty extension shoreline Figure D-5 Bakers Haulover Inlet. 104

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LIST OF REFERENCES ALKHALIDI, M., 2005. Sediment transport in sandy estuaries at equilibrium. PhD dissertation, Civil and Coastal Engineeri ng Department, University of Florida, Gainesville. AUBREY, D.G. and DEKIMPE, N.M., 1988. Perf ormance of beach nourishment at Jupiter Island, Florida. Proceedings of the Beach Preservation Technology Conference L.S. Tait (ed.), Florida Shore and Beach Preservati on Association, Tallahassee, Florida, 409420. CARR DE BETTS, E.E., 1999. An examination of flood deltas at Floridas tidal inlets. MS thesis University of Florida, Gainesville. CHOW, V.T., 1976. Open-Channel Hydraulics New York: McGraw-Hill. CRAIG, P.M., 2004. Users Manual for EFDC-Explorer: A Pre/Post Processor for the Environmental Fluid Dynamics Code, Dynamic Solutions, Knoxville, TN. DELCHARCO, M.J., 1992. Tidal flood ware withdrawal, with special referen ce to Jupiter Inlet, Florida. MS thesis University of Florida, Gainesville GRELLA, M.J., 1993. Development of management policy at Jupiter Inlet, Florida: an integration of technical analys es and policy constraints. Journal of Coastal Research Special Issue 18, A.J. Mehta (ed.), 239-256. MEHTA, A.J.; PARCHURE, T.M., MONTAGUE C.L.; THIEKE, R.J., HAYTER, E.J.; AND KRONE, R.B., 1991. Tidal inlet management at Jupiter Inlet: four th progress report. Report UFL/COEL-91/008 Coastal and Oceanographic Engineering Department, University of Florida, Gainesville. MEHTA, A.J.; MONTAGUE, C.L., and TH IEKE, R.J., 1992. Erosion, navigation and sedimentation imperatives at Jupiter Inlet, Florida: recommendations for coastal engineering management. Report UFL/COEL-92/002 Coastal and Oceanographic Engineering Department, Universi ty of Florida, Gainesville. MEHTA, A.J., and GANJU, N.K., 2003. Organic-rich fine sediments in Florida part III: accumulation and entrapment in a tidal canal. Paper presented at the 7 th International Conference on Cohesive Sediment transport, Virginia Institute of Marine Science, Gloucester Point, VA. MEHTA, A.J.; GRELLA, M.J.; GANJU, N.K., and PARAMYGIN, V.A., 2005. Sediment Management in Estuaries: The Loxahatchee, Florida. Port and Coastal Engineering, P. Bruun (ed.), The Coastal Educati on and Research Foundation, 276-303. ODRONIEC, K.M., 2006. Coastal sediment budget for Jupiter Inlet Florida. MS thesis Civil and Coastal Engineering Department, Univ ersity of Florida, Gainesville. 105

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PATRA, R.R., 2003. Sediment management in low en ergy estuaries: The L oxahatchee, Florida. MS thesis, Civil and Coastal Engineering Department University of Florida, Gainesville. PATRA, R.R. and MEHTA, A.J., 2004. Sediment ation issues in low-energy estuaries: The Loxahatchee, Florida. Report UFL/COEL-2004/002 Civil and Coastal Engineering Department, University of Fl orida, Gainesville, Florida. R.D. INSTRUMENTS (1989). Acoustic Doppler Cu rrent Profiler, Principles of Operation. RODRIGUEZ, E. and DEAN, R.G., 2005. Sedime nt budget analysis and management strategy for Fort Pierce Inlet, Florida. Report UFL/COEL-2005/004 Civil and Coastal Engineering Department, University of Fl orida, Gainesville, Florida. SOULSBY, R.L.; HAMM, L.; KLOPMAN, G.; MYRHAUG, D.; SIMONS, R.R., and THOMAS, G.P., 1993. Wave-current interactio n within and outside the bottom boundary layer. Coastal Engineering 21(1), 41-69. THORNTON, E.B. and GUZA, R.T., 1982. Energy saturation and phase speeds measured on a Natural Beach, Journal of Geophysical Research 87, 9499-9508. VAN RIJN, L.C., 1984. Sediment transport, part I: bed load transport. Journal of Hydraulic Engineering 110(10), 1431-1455. 106

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BIOGRAPHICAL SKETCH Shirshant Sharma was born in Satna, M.P., I ndia in 1984 to Sushma and Shrikant Sharma. He always had a keen interest in becoming an engineer. He develope d interest in Civil Engineering at the age of 14, and started prep aring for it. He took admission in Jabalpur Engineering College, Indias oldest established engineering college to pursue his Bachelors in Civil Engineering. He then decide d to study further, and joined the University of Florida for a Masters in Civil Engineering. 107


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Title: Sand Transport Rates at Jupiter Inlet, Florida
Physical Description: Mixed Material
Copyright Date: 2008

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Source Institution: University of Florida
Holding Location: University of Florida
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SAND TRANSPORT RATES
AT JUPITER INLET, FLORIDA


















By

SHIRSHANT SHARMA


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2007




























2007 Shirshant Sharma




































to my parents









ACKNOWLEDGMENTS

I am sincerely thankful to my advisor and supervisory committee chairman, Dr. Ashish J.

Mehta, for his guidance. I would also like to thank supervisory committee members Dr. Amoldo

Valle-Levinson, Dr. Tian-Jian Hsu, and Dr. John Jaeger. Sincere acknowledgment is due to Dr.

Earl J. Hayter and to Ms. Mamta Jain for their guidance and effort, and also in helping me

understand the basic concepts of modeling done in the thesis. Dr. Andrew Kennedy provided

most of the information given in Appendix A, and programming for Appendix C.

Support for this study was provided by the Jupiter Inlet District Commission, Jupiter,

Florida. Considerable help was provided by Mr. Michael Grella, Executive Director, for making

district's and other data available for analysis.

I must extend thanks to my grandparents, my parents, my sister, my brother-in-law, and

Shweta for the unlimited support and blessings.

Thanks are due to Mr. Sidney L. Schofield of the Coastal and Oceanographic Engineering

Laboratory for providing field data and guiding me in their analysis. I would also like to express

my thanks to the faculty and staff of the Department of Civil and Coastal Engineering for their

help during my study.

Finally, I am thankful to God.









TABLE OF CONTENTS

page

A CK N O W LED G M EN T S ......... ................. ......................... .... ............... .....................4

L IST O F T A B L E S .................................................................................................... . 7

LIST OF FIGURES .................................. .. ..... ..... ................. .9

LIST OF SYMBOLS ............................. .................................. 13

A B S T R A C T ......... ....................... ............................................................ 15

CHAPTER

1 INTRODUCTION ............... .............................. ............................ 17

1.1 Problem Statem ent ................................................... ................. ... ... ... ... 17
1.2 O objective and Tasks........................................................ 18

2 FIELD STU D Y ................................................................................ .... 19

2 .1 S ite D description ................................................................19
2.2 Fixed-Point D ata ..................... ....... ...................... ...................... .. 20
2.2.1 D ata C collection using A D CP............................................ ........... ............... 20
2.2.2 Analysis of ADCP Data for Station 1.................. ............. ............. 22
2.2.3 W after Sam pling ................................................... ............. .. ...... 22
2.2.4 Analysis of N iskin Bottle D ata ................................................... .................23
2.3 Underway Data .............. ................. ........... ..................... ......... 24
2.3.1 D ata Collection ..................................................... ......... .. ............ 24
2.3.2 A analysis of U nderw ay D ata........................................................................ .. .... 24

3 SED IM EN T LO AD ESTIM A TION ......................................................................... ........ 38

3 .1 In tro d u c tio n ................................................................................................................. 3 8
3.2 M odel Setup ............... .............................................................................. 38
3.3 Seaward Sedim ent Boundary Condition...................................... ......................... 39
3.4 M odel Operation ................................................................. ............... 41
3.5 Sedim ent L oads ........................................................................... 42

4 SAND BUDGETS ..................... ........ ... .. ... ... ..................52

4 .1 Introdu action .................. .........................................................................52
4.2 Sand B budget for E astern Zone........................................................................... ...... 52
4 .3 D ata S o u rc e s ............................................................................................................... 5 3
4 .3 .1 T y p e s o f D ata ................................................................................................... 5 3
4.3.1.1 Shoreline data ................................ .................................. 53









4.3.1.2 B each nourishm ent ....................................................................... 55
4 .4 S an d B u dg et A n aly sis........... ...... .............................................................. ........ .............. 55
4.5 Sand B budget for W western Z one.............................................................. .....................57

5 SU M M ARY AND CON CLU SION S....................................................................... ... ..... 71

5 .1 S u m m a ry ..................................................................................................................... 7 1
5.2 Conclusions............................... ....................... ........71
5.3 Recommendations for Further W ork...................................................... ..................72

APPENDIX

A WAVE-INDUCED SAND MOBILITY............................ ....... .................74

A 1 W av e D ata ................................... ....................................................7 4
A .2 Sedim ent M ovem ent ......... ............................................................ ................. ..... 76

B SHORELINE AND BEACH VOLUME CHANGES......................................... ...............80

C ESTIMATION OF SHORELINE CHANGE FROM AERIAL IMAGERY ......................... 92

D BASIS FOR THE LENGTH OF SOUTH JETTY EXTENSION................ .................98

D 1 In tro du ctio n .......................... ...................................................... 9 8
D .2 Outcom e of H ydraulic M odeling Tests ................................... .................................... 100
D.3 Assessment of Jetty based on Shadow Effect....................................................102

L IST O F R E F E R E N C E S ............................................................................. ..........................105

B IO G R A PH IC A L SK E T C H ......................................................................... .. ...................... 107









LIST OF TABLES


Table page

2-1 Shear stress at ebb flow and flood flow ...................................................... ............ 36

2-2 d25, d50, d75 and So values for different times on March 01, 2006...................................37

3-1 Concentrations and grain sizes (d) used by Alkhalidi (2005) as inlet boundary
condition in the 16 boundary cells. ..... ....................................................................... 49

3-2 Time-averaged concentrations for seaward boundary condition in kg/m3 ........................49

3-3 Results from model compared with sampling data of March 1, 2006.............................49

3-4 Volumetric rates of sand transport in Central Embayment....................................51

4-1 Components of sand budget for the eastern zone ................................... .................65

4-2 FDEP surveys for Martin and Palm Beach Counties.............................. ...............65

4-3 Jupiter Inlet updrift beach nourishment volumes (Odroniec, 2006)..............................65

4-4 Volume change rates updrift and downdrift of Jupiter Inlet............................................66

4-5 JID surveys in Palm Beach County ............................................................................66

4-6 Jupiter Inlet trap dredging and placement volumes, 1952-1995.......................................67

4-7 Annual sand transport rates near Jupiter Inlet, 1952-1988 (Mehta et al., 1991)................68

4-8 Annual sand transport rates in the eastern zone for 1974-1986 FDEP budget .................68

4-9 Annual sand transport rates in the eastern zone for 1986-2002 FDEP budget ..................68

4-10 Annual sand transport rates in the eastern zone for 1993-1998 JID sand budget.............69

4-11 Annual sand transport rates in the eastern zone for 1998-2006 JID sand budget..............69

4-12 Rates of accumulation in JID sand trap and ICWW .....................................................69

4-13 Jetty pre- and post-extension volume changes on 1.2 km of south beach .........................70

4-14 Definitions of components of western zone sediment budget. .........................................70

4-15 Annual mean sand transport rates in the western zone.............................................70

A-i Types of sediment transport and frequency of occurrence at the inlet in 3 m depth.........78









C-1 Coordinates and elevations of the control points.......................................... ...............95









LIST OF FIGURES


Figure page

2-1 L location m ap of the study area............................................................... .....................26

2-2 Jupiter Inlet, Central Embayment and tributaries ................................... .................27

2-3 Location of sand trap in Jupiter Inlet channel............................................... ...............27

2-4 Fixed-point sampling Station 1 (26'56'41.28" N and 80'04'36.68" W) and Station 2
(26'56'44.04" N and 80'04'36.34" W )...................................... .......................... 28

2-5 Supporting structure for the A D CP......................................................... ............... 28

2-6 Current velocities recorded at four elevations on 03/01/06 at Station 1..........................29

2-7 Velocity profiles at selected times during flood flow on 03/01/07.............................. 29

2-8 Velocity profiles at selected times during ebb flow on 03/01/07. ....................................30

2-9 Depth-averaged resultant velocity recorded between 02/16/06 to 03/02/06 at Station
1 ............................................................................................. . .3 0

2-10 Suspended sediment concentration time-series at Station 1 on 03/01/06........................31

2-11 Depth-averaged velocity time-series at Station 1 on 03/01/06. .................. ...............31

2-12 Suspended sediment flux time-series at 1.2 m elevation at Station 1 on 03/01/06............32

2-13 Three transects for underway data collection ........................................ ............... 32

2-14 Calibration curve of sediment concentration versus backscatter intensity at Jupiter
In let .......................................................... ..................................... 3 3

2-15 Plot of u versus v and the rotation angle a = 1690 to calculate the resultant velocity at
Transect 1. Positive values denote flood flow. ...................................... ............... 33

2-16 Velocity distribution at Transect 1 for water flowing in at 8:00 pm on 05/09/06. At
that time the incoming suspended sediment flux was maximum. ....................................34

2-17 Velocity distribution at Transect 1 for water flowing out at 2:30 pm on 05/09/06. At
that time the outgoing suspended sediment flux was maximum. .....................................34

2-18 Suspended sediment flux distribution at Transect 1 at 8:00 pm on 05/09/06, when
incoming cross-sectional mean flux was at its peak. ................... ........................ 35

2-19 Suspended sediment flux distribution at Transect 1 at 2:30 pm on 05/09/06, when
outgoing cross-sectional mean flux was at its peak. ................... ......................... 35









2-20 Time-series of cross-sectional averaged flux at three transects based on
m easurem ents on 05/09/06. ...................................................................... ...................36

3-1 Loxahatchee estuary in Cartesian grid with six flow boundaries and seagrass (green
a re a s). ........ ........ ............................................................................ 4 3

3-2 Concentration time-series for cells in column 1 (south end of Transect 1) at the
seaward boundary on 05/09/06. ...... ........................... ........................................43

3-3 Concentration time-series for cells in column 2 at the seaward boundary on 05/09/06....44

3-4 Concentration time-series for cells in column 3 at the seaward boundary 05/09/06........45

3-5 Concentration time-series for cells in column 4 (north end of transect 1) at the
seaward boundary on 05/09/06. ...... ........................... ........................................46

3-6 Contour plot of time-averaged concentrations used to specify seaward boundary
condition. Color scale represents concentration in mg/L. Depth and width of grid are
dim en sionless ........................................................... ................. 4 6

3-7 Tidal plot for September 29 September 30, 2000 at FECRR bridge............................47

3-8 Tidal plot for February 28 March 1, 2006 at FECRR bridge ......................................47

3-9 Transects C, D, F and H where sediment fluxes and loads were calculated. Color
scale represents depth in m eters ......... ................. ................................... ............... 48

3-10 Total load versus time plot for Transect C generated by model over one tidal cycle........48

4-1 Approximate boundaries of eastern and western zones for sand budget analysis.............59

4-2 Volumetric rate components characterizing sand budget for eastern zone......................59

4-3 Length of north beach selected for FDEP budgets. .......................... .......... ........60

4-4 Length of south beach selected for JID budget............................................................60

4-5 Combined JID trap and ICWW annual dredged volume against year of placement.........61

4-6 Components of eastern zone sand budget for 1952-88............................................... 61

4-7 Components of eastern zone FDEP sand budget for 1974-1986................................62

4-8 Components of eastern zone FDEP sand budget for 1986-2002.......................................62

4-9 Components of eastern zone JID sand budget for 1993-1998.....................................63

4-10 Components of eastern zone JID sand budget for 1998-2006.................... ...............63









4-11 Components of sand budget for the western zone. ................................. .................64

4-12 Volumetric sand transport rates in the western zone. .....................................................64

A-i Measured time-series of significant wave height off Melbourne Beach in 8 m depth. .....75

A-2 Joint probability density for wave height and frequency in 8 m, showing typical
wave height of around 0.6 m and frequency of 0.15Hz (7 s wave period).....................75

A-3 Cumulative probability that significant wave height will be less than a given value at
d ep th 3 m ............... ........................... ................................................ 7 7

A-4 Cumulative probability that Shields parameter will be less than a given value for
combined wave-current flow; (b) Some bed load transport, rippled bed (c) bed load
and some suspended load, rippled bed; (d) Strong bed load and suspended load, sheet
flow. The category of no sediment motion is to the left of dashed line in category (b). ...78

A-5 Cumulative probability that Shields sediment mobility parameter will be less than a
given value for pure tidal current flow. Labels are identical to Figure A.4.....................79

A-6 Gross sediment mobilization time-series for 2003-2005 at Jupiter Inlet mouth................79

B JID B each profiles at R -13 ................................................................... ............... 80

B -2 JID B each profiles at R -14 ....................... .......... .......... ................. ............... 81

B -3 JID B each profiles at R -15 ................................................................... ............... 81

B-4 JID Beach profiles at R-16 ................................................................... ............... 82

B -5 JID B each profiles at R -17 ........ .................. .......... ......................... ............... 83

B-6 County beach profiles at R-13. ............. ............................................................. 84

B -7 C county beach profiles at R -14. ........................................ ............................................85

B-8 County beach profiles at R -15 ......... ................ ............. .................................. 86

B -9 C county beach profiles at R -16. ........................................ ............................................87

B -10 C county beach profiles at R -17. ........................................ ............................................87

B-11 Shoreline changes for 1993-2006 (R-13 to R-17)................................... ...............88

B-12 Unit volume changes for 1993-2006 (R-13 to R-17)....................................................88

B-13 Shoreline position at monument R-13 starting February, 1993.............. ...................89

B-14 Shoreline position at monument R-14 starting February, 1993......................................89









B-15 Shoreline position at monument R-15 starting February, 1993...................................90

B-16 Shoreline position at monument R-16 starting February, 1993...................................90

B-17 Shoreline position at monument R-17 starting February, 1993...................................91

C-l Shoreline on November 30, 2004 (10:10 am)........ ..............................93

C-2 Shoreline on A pril 07, 2006 (1:15 pm ) ........................................ ......................... 93

C-3 Beach imaging control points north of camera. ....................................... ............... 94

C-4 Beach imaging control points south of camera............. .........................................94

C-5 Comparison between shoreline positions in 2004 and 2006.........................................96

C-6 Tide on November 30, 2004 corresponding to Figure C.1 (2.25 ft above MLLW). .........96

C-7 Tide on April 7, 2006 corresponding to Figure C.2 (0.5 ft above MLLW) .......................97

D-l Simple model-based results of progression of erosion and accretion as a result of a
shore-norm al structure. .......................... ...... .........................................99

D-2 Jupiter Inlet with south jetty extension segments A (linear) and B (curved).................101

D-3 Inlet flow patterns for existing condition and a modification (flood and ebb) ...............102

D-4 A qualitative assessment of no-inlet shoreline ............................................ ............... 103

D -5 B aker's H aulover Inlet ....................................................................................... ..... 104









LIST OF SYMBOLS

A Linear segment of jetty

a Angle between u and v components of velocity

B Curved segment of jetty; backscatter intensity

b Channel width

C Sediment concentration

Cd Sediment concentration predicted from model

Cg Shoreward component of wave group velocity

C, Sediment concentration observed through sampling

d Grain diameter

d25 Diameter corresponding to 25% of sample

dso Median diameter

d75 Diameter corresponding to 75% of sample

Ed Breaking induced dissipation

E Wave energy

g Gravitational acceleration

p Fluid density

y Shields' parameter

Q Gross sediment mobilization rate

Qnet Net littoral drift southward

Qs Volumetric rate of sand flowing southward bypassing the inlet

Q, Volumetric rate of sand entering the inlet

Qs Volumetric rate of sand leaving the channel and flowing southward

Ql Volumetric rate of sediment lost offshore









Qst Volumetric rate of sediment flowing southward from the inlet

Q.c Volumetric rate of sand flowing into northern ICWW

Qc Volumetric rate of sand flowing to the Central Embayment

Qnw Volume rate of sediment flowing into the Central Embayment from the

North West Fork

Qn Volume rate of sediment flowing into the Central Embayment from the

North Fork

Qf Volume rate of sediment flowing into the Central embayment across the

FECRR bridge

Qs, Volume rate of sediment flowing into the Central Embayment from the

South West Fork

S Specific Gravity

u Velocity in east-west direction

U Resultant velocity

v Velocity in north-south direction

Vud Beach volume change rate updrift of inlet

Vdd Beach volume change rate downdrift of inlet

Vst Volumetric rate of sand accumulation in the trap

Vc Volumetric rate of sand accumulation in the ICWW channel

Vc Volumetric rate of accumulation in the Central Embayment

T Bed shear stress









Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

SAND TRANSPORT RATES AT JUPITER INLET, FLORIDA

By

Shirshant Sharma

May 2007

Chair: Ashish J. Mehta
Major: Civil Engineering

At Jupiter Inlet on the east coast of Florida, sand bypassing by hydraulic dredging has been

used to maintain the navigation channel and nourish the downdrift beach. The basis for this

procedure is a sand budget developed nearly two decades ago. The objective of the present study

was to revisit the budget, and to assess the efficiency of the bypassing procedure. Based on an

analysis of available and newly collected data, rates of sand transport and

accumulation/depletion have been examined for the inlet and its central embayment.

The peak flood flow velocity was found to be approximately 35% greater than the ebb flow

velocity, which as a result caused more sediment to flow into the channel than out of it. This

observation is supported by calculations of bed shear stresses from the velocity measurements.

The increase in the frequency of dredging in the sand trap has resulted in a slight decrease

in the volume of sand deposition in the ICWW relative to the JID trap. The 8 km long stretch of

the beach north of the inlet has remained stable since 1974. Unit and total volume changes for

the 1.2 km length of the beach south of the inlet reflect the difficulty inherent in choosing any

particular period as being representative of a "mean" budget for the beach. In the 1993-1998 and

the 1998-2004 periods, volume change rates were positive, indicating annual accretion. When

the post-jetty reconstruction period was changed to 1998-2006, substantial rates of loss of sand









were found. These losses imply increased effect of wave activity on the erosion potential of the

beach. An inference one can draw from these observations is that inlet sand budget must be

examined each year based on data from the previous year to track the performance of the inlet. In

order to increase the accuracy of future sediment budget analyses, beach profiles should be

obtained over shorter spatial intervals than at present.

The movement of sand in the western half of the Central Embayment is low because of

low flow velocities. However, sand does move into the embayment at its eastern end under the

FECRR bridge, at the rate of about 1,200 m3/yr.









CHAPTER 1
INTRODUCTION

1.1 Problem Statement

Tidal inlets provide navigational access from the sea to bays for commercial and

recreational purposes, and also allow for the necessary exchange of waters for maintaining bay

water quality because the quality of water is poorer landward than in the sea. At sandy inlets,

some of the littoral sediment is often trapped in the inlet channel during flood flow, and some

sediment is transported offshore during ebb flow. The inland and offshore diverted material is

therefore not retained as part of the littoral drift, as would occur in the absence of the inlet. Also,

this interruption in the littoral sediment transport tends to cause recession of shorelines adjacent

to the inlet.

At many inlets steps have been taken to reduce shoreline recession and to keep the inlet

channel free from excessive sediment deposition, so that navigation is possible. Jupiter Inlet on

the Atlantic Coast of southern Florida has also faced similar issues in past, and one of the major

concerns there has been the erosion of sand from the beach south of the inlet. In 1993 the Jupiter

Inlet District (JID), which is the custodian of the inlet's role as a navigation channel, instituted a

management plan to maintain the channel and mitigate shoreline erosion by regularly dredging a

sand trap within the channel, and pumping the sand to the beach south of the inlet. A principal

basis of this plan has been the budget of sediment in the inlet area, which indicates sand

pathways, volumetric rates of sand transport and zones of sand accumulation or loss. A missing

component in the budget was the rates of gain or loss of sand along the contiguous shorelines,

because comprehensive beach surveys covering a sufficiently long time (years) and distances

(several kilometers north and south of the inlet) were not available when the budget was









prepared. The present study was carried out to revisit the sand budget using more extensive and

accurate surveys that have since become available.

1.2 Objective and Tasks

The objective of this study was to determine a sand budget for the Jupiter Inlet area,

including its inner bay called the Central Embayment. The tasks undertaken to meet this

objective included the following:

* Collection of current velocity and suspended sediment concentration data for sand moving
within the inlet channel.

* Use of the numerical model EFDC, originally calibrated and validated by Alkhalidi (2005),
along with collected data to estimate sand loads at selected transects in the inlet channel
and the Central Embayment.

* Reanalysis of data on beach profiles, sand accumulation and sand transfer in the inlet area
compiled in Odroniec (2006), using additional data acquired since that study.

* Updating the sand budget presented in Mehta et al. (1991) for the inlet area, and for the
Central Embayment based on more recent studies (Mehta and Ganju, 2003; Patra 2003;
Patra and Mehta, 2004; Alkhalidi, 2005) and the present work.









CHAPTER 2
FIELD STUDY

2.1 Site Description

Jupiter Inlet has been in existence for over three centuries; however, it has been used as a

waterway mainly in the past century. The Loxahatchee River empties into the Atlantic Ocean

through this inlet, which is located in northern Palm Beach County on the southeast coast of

Florida. The three main tributaries of the estuary are the Northwest Fork, the North Fork and the

Southwest Fork. In addition, Jones Creek and Sims Creek, which are much smaller tributaries,

also feed into the estuary through the Southwest Fork. Figures 2-1 and 2-2 show the general

location map of the study area. The navigation channel (maintained by JID) runs westward from

the inlet, under the FECRR (Florida East Coast Railroad) bridge, and through the Central

Embayment approximately 14 km upstream of the inlet. The navigation channel has a bottom

width of about 31 m and is maintained at -1.75 m (referenced to the National Geodetic Vertical

Datum 1929, NGVD 29, or -2.21 m with reference to the North American Vertical Datum 1988,

NAVD 88).

Figure 2-3 shows the location of the sand trap. Mainly, coarser sediment is deposited in the

trap, and lesser amount of smaller sediment is deposited elsewhere in the channel. The mean

diameter of sediment collected in the sand trap is about 0.80 mm. The reason for the relatively

large diameter in the trap is that normally the finer sediment remains in suspension due to the

high flow velocities in the channel, and thus does not deposit in the trap.

To estimate the rate of transport of sediment in suspension, data were collected in two

different ways, at a fixed point and from a vessel underway.









2.2 Fixed-Point Data

Fixed-point data collection involved two methods. One was using an Acoustic Doppler

Current Profiler (ADCP), which measured the flow velocity at different heights above the bottom

in three mutually perpendicular directions. Two types of ADCPs were used: (1) a Workhorse

WH1200 from RD Instruments, and (2) Aquadopp current profiler from Nortek. The other

method involved the use of a Niskin sampling bottle, which collected water samples (for

determination of suspended sediment concentration) at four elevations above the channel bed.

Current measurements using ADCP were carried out twice. The first period was from 10/13/05

to 11/16/05, and the second from 02/16/06 to 03/02/06. Data using the Niskin bottle were also

collected twice, on 11/17/05 and on 03/01/06 at Station 1 (Figure 2-4).

2.2.1 Data Collection using ADCP

ADCPs operate by measuring the reflection of an acoustic signal from particulate matter in

water based on the Doppler-shift principle. While these instruments are primarily used to

measure the velocity of such particles (and thereby deduce the speed of current transporting

particles), they can also provide information on the concentration of particulate matter.

Conventional ADCPs typically use a "Janus configuration" consisting of four acoustic beams,

paired in orthogonal planes, where each beam is inclined at a fixed angle with the vertical

(usually 20-30). The sonar measures the component of velocity projected along the beam axis,

averaged over a range-cell, whose along-beam length is roughly half that of the acoustic pulse.

This information is measured in the form of the intensity of the received reflection, also referred

to as the backscattering strength, backscatter intensity or signal amplitude (measured in decibels)

(R.D. Instruments, 1989). The ADCPs used recorded this information in instrument-generated

data files.









At the study site each ADCP was installed on a tripod attached to the bottom by three

aluminum pipes jetted into the bed. The top of the instrument was 2 m above the bed,

approximately 3 m below the mean water level. Figure 2-5 shows the design of the supporting

structure.

Each ADCP was oriented with respect to the geographic north, so that the velocity could

be measured in two components, and the resultant velocity of water flowing into and out of the

channel. The angular difference between the east-west direction and the axis of the inlet channel

at the site was taken as 15. The ADCPs transmitted a ping from the transducer element. The

return echo was received at the instrument over an extended period, with echoes from shallow

depths arriving sooner than the ones from greater depth ranges. Profiles were produced by range-

gating the echo signal, i.e., the echo was split into successive segments called depth-bins, which

correspond to successively deeper depth ranges. The ADCP was configured to give the velocities

at 11 elevations. The highest elevation was 1.8 m above the base of the tripod (taken as the

nominal bed datum). The spacing between two consecutive bins was 0.2 m. All acoustic current

profilers have a region immediately in front of the transducers, called the blanking distance, over

which no measurements can be made. This region is required for the transducer and electronics

to recover from the high-energy transmitted pulse. The blanking distance for the instruments

used was 0.2 m. There is also a zone close to the bed, from where data received are not stored

due to their corruption by the presence of the bed.

Only the top four elevations (1, 1.2, 1.4 and 1.6 m above datum) were usable because the

presence of the supporting structure influenced, in a negative way, the acoustic signals from

lower elevations. Velocities measured in the north-south and east-west directions were used to

calculate the resultant velocities (vectors) of water into and out of the channel.









The first set of current observations was made during the period 10/13/05 to 11/16/05

using both ADCPs, one at each station. The ADCP at Station 1 was not in operation at the time

sampling using the Niskin bottle was carried out on 11/17/05. Despite this limitation, sampling

was done assuming that current data would be recorded by the ADCP at Station 2.

Unfortunately, that device was recovered damaged due to an undetermined cause. As a result, a

second set of sampling with the bottle was carried out at Station 1 on 03/01/06, when the ADCP

was there in operation.

2.2.2 Analysis of ADCP Data for Station 1

Based on the ADCP data at Station 1, Figure 2-6 shows the variation of velocity at four

elevations above the bed (datum). The period covered is 9.5 hours on 10/13/05, which is also the

duration over which water sampling was carried out. In Figures 2-7 and 2-8, velocity profiles at

flood flow and ebb flow, respectively, have been plotted at selected times. All profiles follow the

log-velocity distribution characteristic of open channel boundary layer flows. These yield the

following values of the friction velocity u* and the bed shear stress Tb (using a density of 1,027

kg/m3 for seawater) tabulated in Table 2-1. In general, the shear stresses are higher during flood

than ebb, which correlates with the observation of net sand inflow from the Ocean into the inlet

channel.

2.2.3 Water Sampling

The Niskin bottle is a 0.64 m long plastic tube (with a diameter of approximately 0.12 m)

that is lowered into water while open at both ends. Its approximate volume is 2.37 liters. The

bottle was mounted in a steel frame, which could be submerged in water by a tethered rope, and

when the frame reached the desired depth, water could pass freely through the bottle. At that









point both ends were closed by hinged lids to capture a sample of water at that depth by sending

a "messenger" weight down the rope to which the bottle frame was tethered.

During each sampling study, the bottle was used to collect water samples at four elevations

above the bed (0.3, 0.6, 0.9 and 1.2 m) at different times. The samples were filtered on site using

standard coffee filters, and the sediment collected was stored in zip-lock bags along with the

filters. The samples were then oven-dried for 48 hours in the laboratory. Each dried filter with

the sediment was weighed in a Mettler balance, and the filter was also weighed without the

sediment, after removing it from the filter. Thus the weight of sediment could be calculated.

Sediment concentration was obtained by dividing the weight of the sediment by the volume of

water of the sample in the bottle.

2.2.4 Analysis of Niskin Bottle Data

Sediment flux flowing into or out of the channel was calculated by multiplying the

suspended sediment concentration at an elevation at a time by the corresponding velocity.

Synchronous velocity and concentration values were only available for the elevation of 1.2 m

above the channel bed, so the time-series of flux for this elevation only was obtained.

Sieve analysis was carried out for the sediment collected on the filters, using sieve sizes of

0.50, 0.25, 0.125 and 0.0625 mm. Table 2-2 gives the d25, ds0, d75 percentile diameters and the

corresponding sorting coefficient (S = Jd5 Id25 ) for different times. Based on the well-known

MIT classification, the sediment was found to fall in the range of fine to medium sand.

Figures 2-10 and 2-11 show time-series of suspended sediment concentration (at different

elevations) and depth-averaged velocity, respectively. It is observed that the concentrations are

comparable at all elevations when the velocity is around 0.5 m/s. However, at peak velocities

(0.8-1.0 m/s), concentrations at 0.3 and 0.6 m are about 150% of the values at the top two









elevations. This behavior suggests that at higher velocities, larger sand particles that otherwise

would travel as bed load also came into suspension.

The time-series of sediment flux at 1.2 m elevation using synchronous data on velocity and

concentration is shown in Figure 2-12. Positive values of flux mean transport into the channel

and negative values indicate transport out of the channel.

2.3 Underway Data

2.3.1 Data Collection

An Aquadopp ADCP was used to collect the backscatter intensity data underway in the

channel (Vik Adams, Coastal and Oceanographic Engineering Laboratory, personal

communication). The device was mounted on the side of a 5.2 m long McKee boat and was

submerged in water to a depth of 0.3 m. A closed polygonal path was predefined along which the

vessel was navigated. While moving along that path, the vessel crossed the channel three times at

three selected transects. Figure 2-13 shows the location of these transects. Backscatter intensity

data from the ADCP were analyzed for times only when the vessel traversed a transect. From

Transect 1 data from 17 different locations along the transect was taken. For Transects 2 and 3,

data from 29 different locations were obtained.

Backscatter intensity data were collected for each transect 21 times. Depth profile along

each transect (for every one of these 21 sets of observations) was also recorded. Depth between

the instrument and the channel bed was subdivided into 11 depth-bins for the first and second

transects, and for the third transect into 7 bins. The spacing between two consecutive bin

elevations was 0.5 m.

2.3.2 Analysis of Underway Data

Water sampling was also done using the Niskin bottle on 09/05/2006 at one location along

the selected path of the vessel. The samples were collected in the same way as explained earlier,









but at two elevations, surface and mid-depth. Sediment concentrations were calculated using the

procedure given in Section 2.2.3. Concentrations at different elevations were plotted against the

corresponding backscatter intensity values (in decibels) recorded by the ADCP. The regression

equation for the best-fit curve was used to calibrate for the concentration from the backscatter

intensity values for all observation points. Figure 2-14 shows the plot between concentration and

backscatter intensity values, and the best-fit equation.

The calibration equation relating the suspended sediment concentration C (kg/m3) with the

backscatter intensity B (db) is

C = 2x10-9eo 1536B (2-1)

Where, 2x109 and 0.1536 are the regression coefficients.


Contours plots were obtained for concentration and velocity for the three transects. Given u

as the velocity in the east-west direction and v in the north-south direction, Figure 2-15 shows a

plot for u versus v and the angle a by which the u had to be rotated to calculate the resultant.

Similar plots were obtained for Transects 2 and 3.

The resultant velocity Uat any position along a transect was calculated using the following

equation

U= ucosca-vsina (2-2)

For example:

For Transect 1, bin 1, consider u = 0.683 m/s and v = -0.287 m/s. Therefore,

U = (0.683) cos(169) (-0.287) sin(169)

= 0.3725 m/s

For illustrative purposes, Figures 2-16 and 2-17 show cross-sectional distribution of the

velocity at the time of maximum sediment influx, and outflux, respectively. It was found that the












cross-sectional mean velocity of water flowing in was approximately 35% higher than the


corresponding velocity of water flowing out. Figures 2-18 and 2-19 illustrate distributions of


maximum flux (kg/m2 s) over the cross-section (Transect 1) for water flowing in and out,


respectively.


Figure 2-20 shows time-series of cross-sectional average suspended sediment flux at each


transect. It is observed that a higher cross-sectional mean flux of sediment occurred when water


moved into the channel compared to when it moved out. This difference is explained by


sediment deposition that takes place inside the channel.


I I "- I I





-. .,-I I rJIo




I i
A I -*-

rA r


,:, ,- _. 11 ,,1
nAd
o m of tr l





-Figure 2-1 Location map of the study area (Source: www.ive.com).



























Figure 2-2 Jupiter Inlet, Central Embayment and tributaries (adapted Google image)


Figure 2-3 Location of sand trap in Jupiter Inlet channel (adapted Google image).































Figure 2-4 Fixed-point sampling Station 1 (26'56'41.28" N and 80'04'36.68" W) and Station 2
(26'56'44.04" N and 80'04'36.34" W) (adapted Google image).


U VmL.




~ 0 r


2 r m


j~


Figure 2-5 Supporting structure for the ADCP.


ii4~~l5Nf~ .,1%j '~r~q!25~5rrrO


L---


Y


- 'r.~r1


.c.u~
































---1 6m
-1-I 4m
1 2m
--1 Om


-0 5











-15

800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900
Time (hours)




Figure 2-6 Current velocities recorded at four elevations on 03/01/06 at Station 1.


Rood Fow


0 C02 C4 06 D-B
Yelocirty OnVse~c)


1.2 1-4 1-6


Figure 2-7 Velocity profiles at selected times during flood flow on 03/01/07.


a' 1200
* 1300
1 400
1 ~aoO











Ebb Flow




10----------------------y- y---- 7- _








I /8:
6/

















/ i it










'3 0
0



-0.5




-1
0 50 100 150 200 250 300
Time (hours)



Figure 2-9 Depth-averaged resultant velocity recorded between n 02/1606 to 03/02/06 at Station
1.
1.













0.1

0.09

0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0
7


* I I I I- -- ---
:--


14:00 15:00 16:00 17:00 18:00


Figure 2-10 Suspended sediment concentration time-series at Station 1 on 03/01/06.


1.2

1-

0.8

0.6

0.4

0.2-

0-

-0.2

-0.4-

-0.6

-0.8

-1


7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00

Time (Hours)





Figure 2-11 Depth-averaged velocity time-series at Station 1 on 03/01/06.


8:00 9:00 10:00 11:00 12:00 13:00

Time (hours)


---At 0.6m
- -At 0.9m
At 1.2m

---At 0.3m


*:00


-- Series
















0.01


0.005 .


0.


-0.005

E
S-0.01
X
E -0.015


-0.02 .


-0.025 .


-0.03 I I I I
7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00
Time (hours)



Figure 2-12 Suspended sediment flux time-series at 1.2 m elevation at Station 1 on 03/01/06.










L,-2
28.9455 -


26,9450


26.944.5


26.9440

Transc. I
26.0435



-80.070 -B~.076 -80.074 -0.072 -80.070
LON


Figure 2-13 Three transects for underway data collection (Courtesy: Professor Amoldo Valle-
Levinson).












0.0060


0.0050


E 0.0040


0.0030


0.0020 .


0.0010 .


0.0000
60 65 70 75 80 85 90 95 100
Backscatter Intensity (db)



Figure 2-14 Calibration curve of sediment concentration versus backscatter intensity at Jupiter
Inlet.












i11I- ,I .. 1 ,


Figure 2-15 Plot of u versus v and the rotation angle a =
Transect 1. Positive values denote flood flow.


1690 to calculate the resultant velocity at












Maximum Velocity Flowing In at Transect 1 (m/sec)
2
-2 _____ __ee_ l"
Tide Level
1 NAV........ ............ M LLW
1 ~ ~ ~ ~ ----- ... .....~-k ----;--- ---


-m


0


.005 .015 .025 .035 .045
Distance (km)


.055 .065 .075


Figure 2-16 Velocity distribution at Transect 1 for water flowing in at 8:00 pm
that time the incoming suspended sediment flux was maximum.


Maximum Velocity Flowing Out at Transect 1 (m/sec)


NAV/D :.-Tide Level :
0_ --L- __ -

MLLW '

-1



r--3


.005 .015 .025 .035 .045 .055 .065 .075
Distance (km)


Figure 2-17 Velocity distribution at Transect 1 for water flowing out at 2:30 pm
that time the outgoing suspended sediment flux was maximum.


on 05/09/06. At


,1.8


n 6



0.4


0.2


0


on 05/09/06. At


-4 ....












Maximum Flux Flowing In at Transect 1 (Kg/cu.m sec)
2
Tide :Level NAVD MLLW
1 ... .......... .. :. I ..... .. .....ML L W


-6
.005 .015 .025 .035 .045 .055
Distance (km)


Figure 2-18 Suspended sediment flux distribution at Transect 1
incoming cross-sectional mean flux was at its peak.


0.01

0.009


0.006

,:, ,:,,:if,



,, ,-,,1 I


at 8:00 pm on 05/09/06, when


Maximum Flux Flowing Out at Transect 1 (Kg/cu.m sec)

-~NAVD :
------------
o W Tide

MLLW: : .Tide Level


- -3


-4


0.01

0.009

0.008

0.007

0.006








0.002

0.001


Distance (km)


Figure 2-19 Suspended sediment flux distribution at Transect 1 at 2:30 pm on 05/09/06, when
outgoing cross-sectional mean flux was at its peak.











Flux vs Time at three transects


0.002


0.0015


" 0.001

E
0.0005
X
LL
0
10

-0.0005


-0.001


Time (hrs)




Figure 2-20 Time-series of cross-sectional averaged flux at three transects based on
measurements on 05/09/06.

Table 2-1 Shear stress at ebb flow and flood flow
Time Flow stage u* Tb
(hr) (m/s) (Pa)
8:00 Ebb 0.20 43.0
9:00 Ebb 0.15 23.2
12:00 Flood 0.17 30.9
13:00 Flood 0.26 68.2
14:00 Flood 0.27 75.5
15:00 Flood 0.23 56.0
16:00 Flood 0.20 41.7
18:00 Ebb 0.17 31.1
19:00 Ebb 0.21 44.8


-- Transect 2
---Transect 3
Transect 1


1.. -C

& -^^









Table 2-2 d25, dso, d75 and So values for different times on March 01, 2006
Time d75 dso d25 So
(hr) (mm) (mm) (mm)
8:00 0.100 0.135 0.089 1.05
9:00 0.165 0.120 0.082 1.41
10:00 0.160 0.120 0.082 1.39
11:00 0.120 0.090 0.078 1.24
12:00 0.185 0.155 0.105 1.32
13:00 0.120 0.090 0.078 1.24
14:00 0.120 0.090 0.078 1.24
15:00 0.115 0.089 0.076 1.23
16:00 0.110 0.087 0.075 1.21
17:00 0.100 0.085 0.074 1.16









CHAPTER 3
SEDIMENT LOAD ESTIMATION

3.1 Introduction

Environmental Fluid Dynamic Code model setup for the Central Embayment was carried

out by Alkhalidi (2005), who also calibrated and validated the model using sand trap

accumulation data for a 30-day period from September 17 to October 16, 2000. The original

setup is summarized; details are found in Alkhalidi (2005). In the present study, suitable

modifications were made to that setup. These modifications, specifically with respect to the

seaward boundary condition for sediment transport, are described in this chapter.

3.2 Model Setup

The model was setup in the following way:

* Grid generation for the model was done using EFDC-Explorer (a Microsoft Windows
based pre-processor and post-processor) developed by Craig (2004). To generate the grid,
the grid type, cell size, number of water and sediment layers, time step, and the topography
and domain of the water body were specified through input files. Figure 3-1 shows the grid
generated by the Explorer. Grid numbers were specified in the input file.

* The initial conditions for the water column (specified in Explorer) included the number of
size-classes and the grain size representing each size-class, the initial fraction of each size-
class, bed porosity, and bed bulk density for every cell in the input files. Boundary
conditions were assigned using a concentration time-series as explained in Section 3.3. The
seaward boundary condition at Jupiter Inlet was assigned from underway data collection at
Transect 1 as explained in Section 3.3. Suspended sediment concentrations were measured
along that transect (Chapter 2).

* The hydrodynamic model calculates the water surface elevation, velocity, and shear stress
(and shear velocity). Then, the mode of sediment transport (bed load or suspended load) is
determined at the center of every cell using the approach of van Rijn (1984). When the bed
shear velocity calculated by the model is less than the critical shear velocity, which is also
calculated by the model in the same time-step, no bed erosion takes place and there is no
bed load transport. Sediment in suspension under this condition will deposit onto the bed.
When the bed shear velocity exceeds the critical shear velocity, but is less than the settling
velocity calculated by the model, sediment is eroded and transported as bed load. Sediment
in suspension under this condition will deposit onto the bed. When the bed shear velocity
exceeds both the critical shear velocity and the settling velocity, bed load transport ceases
and the eroded sediment is transported as suspended load. Thus, after the model calculates
the bed shear velocity, critical shear velocity and the settling velocity, it compares the three









quantities and checks for the above three conditions. After determining the transport mode,
the magnitudes of bed load and the suspended load are calculated. The governing equations
of the sediment transport model are solved to determine rates of erosion/accumulation, new
bed level, and new bed composition. Finally, the outputs of the hydrodynamic and the
sediment models are used as initial conditions for the next time-step calculations.

The bed roughness coefficient in the model is composed of two components, a fixed

component, which was set to 0.02 m everywhere on the model grid, and a variable component

that took into account the presence of seagrass. The variable component was set to 0.035 m in

the seagrass area (Chow, 1976), and 0 everywhere else.

The hydrodynamic boundary conditions at the six boundaries were specified by Alkhalidi

(2005) as follows:

* Boundary (1): Water surface elevation at inlet.

* Boundary (2): Water surface elevation at south ICWW.

* Boundary (3): Water surface elevation at north ICWW.

* Boundary (4): Water discharge at Southwest Fork.

* Boundary (5): Water discharge at Northwest Fork.

* Boundary (6): Water discharge at North Fork.

The following sediment boundary conditions were specified by Alkhalidi (2005):

* Boundary (1) at the Jupiter Inlet entrance, as described later.

* Boundary (5) at the upstream end of the Northwest fork (relationship between discharge
and suspended sediment concentration derived from hydrologic data).

* At boundaries (2), (3), (4) and (6) the suspended sediment loads were assumed to be
negligible.

3.3 Seaward Sediment Boundary Condition

Table 3-1 gives the constant concentration values initially used by Alkhalidi (2005) at the

inlet boundary in different layers, for different particle sizes. These concentrations were adjusted

until an agreement was obtained between the calculated and measured dredging volume rates.









In the present study it was found that the sediment flux values generated by the model at

Station 1 were not compatible with results from water sampling, but were considerably larger. In

order to correct for this discrepancy, the seaward boundary condition was specified by using

underway data for Transect 1.

The new boundary condition was specified as follows:

* Suspended sediment concentrations at 11 elevations and 17 observation points were
selected along Transect 1 (Figure 2-10), which was close to the seaward boundary of the
model.

* Since sampling was done 21 times along Transect 1 from 12:30 pm to 11:00 pm on May
09, 2006, concentration values could be determined 21 times. Contour plots for
concentration were then obtained for the cross-sectional area covered by the ADCP. The
area was divided into 16 cells of a 4X4 grid. Using the mean concentration for each cell for
all 21 repetitions, 16 time-series were obtained. These time-series are shown in Figures 3-
2, 3-3, 3-4 and 3-5.

* Based on these concentration time-series, obtained from the analysis of backscatter data
collected at Transect 1, time-averaged concentration values in Table 3-2 were determined.
Figure 3-6 plots these values.

* The time-averaged concentrations for the 16 cells were used to specify the spatial variation
in the concentration relative to (or as a function of) the cross-sectionally averaged
concentration across the boundary. That is, the concentration in each cell was specified as
a certain percentage of the cross-sectionally averaged concentration. The cross-sectionally
averaged concentration was varied as a function of the time-derivative of the predicted
water surface elevations at transect 1 over the model simulation period. The time-varying
concentration in each of the 16 was obtained by multiplying the time-varying cross-
sectionally averaged concentrations by the respective percentage difference.

Although the ADCP did not cover the entire cross-section at Transect 1 width-wise, due to

limitations imposed by the draft of the vessel, the device did cover approximately 85% of depths

in the channel.

It should be pointed out that the 16-cell grid was dimensionless, with the thickness of each

layer equal to a quarter of the local depth. Accordingly, it was assumed that the cross-sectional

area covered by the ADCP was considered to be "stretched" in order to represent the actual

channel boundary. It should also be pointed out that the movement of particles was low near the









banks of the channel because of lower flow velocities arising from boundary friction. Therefore,

the error introduced in the total sediment load calculations due to the absence of sediment data

close to the banks was likely to have been small.

3.4 Model Operation

The model was set by Alkhalidi (2005) to give the results for the year 2000 from Julian

day 243 (August, 30th 2000) until day 365 (December, 31st 2000). On the other hand, in the

present study, suspended sediment sampling was carried out on March 1, 2006. Therefore, a day

was selected in the 243-365 Julian day range of 2000 modeling which had a tidal range similar to

that on March 1, 2006. Figures 3-7 and 3-8 show tides for September 30, 2000 and March 1,

2006 at the FECRR bridge inside Jupiter Inlet. The model was thus calibrated to yield sediment

fluxes for different transects (Figure 3-9) for March 1, 2006 (based on the similarity in tidal

conditions between March 1, 2006 and September, 30 2000).

The model was run for a 30 day "cold-start" period, beginning approximately 30 days prior

to the desired time of "hot-start" period. This was necessary because, according to the required

procedure, results obtained at the end of the cold-start period are used as the initial condition for

the next, hot-start, period. The time-step for the numerical simulation was selected to be 4 s.

Table 3-3 gives concentrations obtained from the model and those measured. Also given

are percent differences between prediction and measurement. Errors of this magnitude are not

surprising because, as shown in Appendix A, sediment mobility at the inlet is strongly dependent

on the waves near the inlet mouth, whose effect was not included in the model. Given the likely

variability in concentration introduced from this factor, it was concluded that concentrations

generated by the model could be used in a post-processing program of EFDC to predict sediment

fluxes (and loads) across selected transects in the Loxahatchee grid. Figure 3-9 show these

transects (C, D, F and H).









3.5 Sediment Loads

Suspended and bed loads were generated by the model for every cell and every time step.

However, because the model took approximately 30 days to stabilize to give accurate results,

values generated over the last tidal cycle were accepted. The model gave sediment mass rates

(loads) based on sediment fluxes across each transect with known cross-sectional area. These

loads were plotted against time and the net sediment load was calculated using the trapezoidal

rule. As an example, Figure 3-10 shows the plot for load versus time for Transect C. From the

net load, the annual volumetric rate (m3/yr) of sediment transport across the transect was

calculated as shown below with an example.

For example, the calculations for Transect C are as follows:

Net mass rate flowing over one tidal cycle (12 hr) = 0.03546 kg/s.

Total sediment flowing into the embayment over one tidal cycle = 3,063 kg.

Assume the wet bulk density of sand = 1,920 kg/m3.

Annual volumetric rate of sediment into the embayment = 1,164 m3/yr.

In the above example, positive sign indicates sediment transported into the Central

Embayment. The volumetric rates of sediment transport across the four transects are given in

Table 3-4. Sediment mass rates for Transects D, F and H were found to be negligible.







































Figure 3-1 Loxahatchee estuary in Cartesian grid with six flow boundaries and seagrass (green
areas).


--- Column 1 Cell 1
-U-Column 1 Cell 2
Column 1 Cell 3
Column 1 Cell 4


120000 140000 160000 180000
Time (hrs.)


200000 220000


Figure 3-2 Concentration time-series for cells in column 1 (south end of Transect 1) at the
seaward boundary on 05/09/06.


(5)






N





1km

[4;^^


(6)


1 20E-03




1 00E-03




8 00E-04

-

S
S6 00E-04


0

400E-04




2 00E-04
2 Q 4-


r, *'


. -1 1 1


0 00E+00 I
10 OC


00














2.00E-03


1.80E-03


1.60E-03


1.40E-03


1.20E-03


1.OOE-03


8.00E-04


6.00E-04


4.00E-04


2.00E-04


0.00E+00 -
10.0000


18.0000


-*-Column 2 Cell 1
---Column 2 Cell 2
Column 2 Cell 3
Column 2 Cell 4


20.0000 22.0000


Figure 3-3 Concentration time-series for cells in column 2 at the seaward boundary on 05/09/06.


12.0000 14.0000 16.0000
Time (hrs.)















1.40E-0?




1.20E-0I:




1.OOE-0I:



8.OOE-CI -




6.OOE-CI -




4.00E-C :-




2.00E-C :-




O.OOE+C-,:-




-2.00E-03


at~~~


14 1-1'0'y) I 0


---Column 3 Cell
-U-Column 3 Cell
Column 3 Cell
Column 3 Cell


Time (hrs.)




Figure 3-4 Concentration time-series for cells in column 3 at the seaward boundary 05/09/06.













1.40E-02



1.20E-02



1.OOE-02



8.00E- 0



6.00E- :-



4.00E-C0



2.00E- 0



O.OOE+CO0:
II-2


2.00E-03


Concentration time-series for cells in column 4 (north end of transect 1) at the
seaward boundary on 05/09/06.


Concentration (kg/rn3)



3





/ 215


I
Southern Bank


Width dimensionlesss)


Northern Bank


Figure 3-6 Contour plot of time-averaged concentrations used to specify seaward boundary
condition. Color scale represents concentration in mg/L. Depth and width of grid are
dimensionless.


-*-Column 4 Cell 1
---Column 4 Cell 2
Column 4 Cell 3
Column 4 Cell 4


ljc ~ 1LC~jCC' ~ c'~jj 1~~ jC'~j Lj Ii.C


Figure 3-5


Time (hrs.)











Jupiter Inlet, U.S. Highway 1 Bridge, Florida
)00-09-29 2000-09-30 2000-09-30 2000-09-30 2000-09-30 2000-10-01
:08 PM EDT 5:39 AM EDT 11:38 AM EDT 6:05 PM EDT 11:50 PM EDT 6:21 AM EDT


2000-10-01 2000-10-01
12:23 PM EDT 6:49 PM EDT


0 L 12 I- 1 4 5 ,: :' 10 11 1- 1 7 34 5 t i 10 11 1 1 4 5 I O 10 11 1- 1 2 4 6 t 1


Figure 3-7 Tidal plot for September 29 September 30, 2000 at FECRR bridge (Source:
www.mobilegeographics. com).


2006-03-01 2006-03-01
4:02 AM EST 9:54 AM EST


Jupiter Inlet, U.S. Highway 1 Bridge, Florida
2006-03-01 2006-03-01 2006-03-02
4:24 PM EST 10:21 PM EST 4:51 AM EST


2006-03-02 2006-03-02 2(
10:40 AM EST 5:12 PM EST 11


,0: 11 1 1 2 7 J '. .. 7 8 9 1,' 11 11 1 3 4 .. 9 1,3 11 12 1 ; J r ,. 1' 10 LIl 1 12 1 7 4 5 .. 1


Figure 3-8 Tidal plot for February 28 March 1, 2006 at FECRR bridge (Source:
www.mobilegeographics. com).









Depths (mn)


t A;
'<.:&,/.


4 4


1km F-
I I


I7 It


-1
-2

--3

-4

-5




-6
I


Figure 3-9 Transects C, D, F and H where sediment fluxes and loads were calculated. Color scale
represents depth in meters.


2


1.5


S1
o


0.5
00
Cu
a 0


2736


-2- 1


;j. i.J..; B2;


Time (Days)


Figure 3-10 Total load versus time plot for Transect C generated by model over one tidal cycle.


-, > 'II


-ir;









Table 3-1


Concentrations and grain sizes (d) used by Alkhalidi (2005) as inlet boundary
oc edition in the 16 boundary cells


Sediment concentration (mg/L)
Layer
d= 0.188 mm d = 0.375 mm d = 0.750 mm

1 7.50 5.40 0.10

2 2.27 0.50 0.00

3 0.80 0.07 0.00

4 0.12 0.01 0.00



Table 3-2 Time-averaged concentrations for seaward boundary condition in kg/m3
Layer no. Column 1 Column 2 Column 3 Column 4
(South side) (North side)
1 0.00040 0.00070 0.00065 0.00150
2 0.00040 0.00050 0.00080 0.00180
3 0.00045 0.00050 0.00110 0.00210
4 0.00048 0.00053 0.00180 0.00250


Table 3-3 Results from model compared with sampling data of March 1, 2006
Time (am) Concentration(Cp) Concentration (C,) Percent
predicted from model observed through difference
(kg/m3) sampling (C,-Cp)/CpX100
(kg/m3)
7:55 0.178 0.139 -22
8:02 0.133 0.141 6
8:10 0.116 0.144 24
8:34 0.105 0.151 43
8:41 0.089 0.153 71
8:46 0.095 0.154 63
8:54 0.102 0.156 53
9:00 0.278 0.158 -43
9:08 0.123 0.161 31
9:14 0.295 0.162 -45
9:20 0.105 0.164 57
9:26 0.088 0.166 88
9:32 0.621 0.168 -73
9:40 0.093 0.170 83
9:47 0.120 0.172 43









Table 3-3 Continued
Time (am) Concentration(Cp) Concentration (C,) Percent
predicted from model observed through difference
(kg/m3) sampling (C,-Cp)/CpX100
(kg/m3)
10:00 0.133 0.176 32
10:04 0.122 0.177 45
10:06 0.555 0.178 -68
10:11 0.103 0.179 74
10:42 0.135 0.188 39
10:46 0.131 0.189 44
10:53 0.242 0.191 -21
10:57 0.157 0.193 23
11:03 0.126 0.194 54
11:10 0.153 0.196 28
11:14 0.114 0.197 73
11:21 0.120 0.120 66
11:30 0.110 0.202 83
11:34 0.164 0.203 24
11:41 0.148 0.205 39
11:49 0.127 0.208 64
12:00 0.110 0.211 92
12:04 0.113 0.212 88
12:12 0.124 0.214 73
12:16 0.120 0.216 79
12:27 0.133 0.219 65
12:32 0.130 0.220 69
12:38 0.130 0.222 71
12:46 0.144 0.224 56
13:30 0.180 0.237 32
13:32 0.175 0.238 36
13:39 0.139 0.240 73
13:45 0.163 0.242 48
14:00 0.159 0.246 55
14:03 0.182 0.247 36
14:06 0.192 0.248 29
14:13 0.144 0.250 73
14:30 0.131 0.255 94
14:32 0.137 0.256 86
14:36 0.467 0.257 -45
14:40 0.192 0.258 34
15:00 0.170 0.264 55
15:02 0.162 0.264 63
15:05 0.179 0.265 48









Table 3-3 Continued
Time (am) Concentration(Cp) Concentration (C,) Percent
predicted from model observed through difference
(kg/m3) sampling (C,-Cp)/CpX100
(kg/m3)
15:32 0.222 0.273 23
15:35 0.199 0.274 38
15:39 0.239 0.275 15
15:42 0.228 0.276 21
16:00 0.210 0.281 34
16:02 0.206 0.282 37
16:10 0.273 0.284 4
16:10 0.186 0.284 53
16:29 0.120 0.290 45
16:31 0.240 0.290 21
16:35 0.237 0.292 23
16:39 0.202 0.293 45
17:00 0.194 0.299 54
17:02 0.247 0.299 21
17:06 0.169 0.301 78
17:09 0.182 0.302 66
17:30 0.212 0.308 45
17:33 0.224 0.309 38
17:34 0.216 0.309 43
17:38 0.252 0.310 23
17:58 0.222 0.316 42
18:00 0.231 0.316 37
18:02 0.206 0.317 54
18:05 0.185 0.318 72


Table 3-4 Volumetric rates of sand transport in Central Embayment
Volumetric rate of
ic r o Volumetric rate of Net volumetric rate
suspended load
suspend ld bed load moving of sand moving into
Transects moving into Central
S m entr into Central Central Embayment
Embayment (M3 3
(m3byr) Embayment (m3/yr) (m3/yr)
C 2092 -927a 1164
D 0 0 0
F 0 4 4
H 0 0 0
a positive sign indicates sediment transported landward.









CHAPTER 4
SAND BUDGETS

4.1 Introduction

In this chapter, sand budgets are presented for Jupiter Inlet and the Central Embayment.

The estuary is conveniently divided into an eastern zone, which includes Jupiter Inlet, and a

western zone consisting of the Central Embayment. Figure 4-1 shows the two zones. The

volumetricc) transport rate components of each budget account for sediment loads entering,

depositing within, and leaving, the two zones.

4.2 Sand Budget for Eastern Zone

Volumetric rate components characterizing sand budget for the eastern zone are indicated

in Figure 4-2. Table 4-1 gives the definitions of these quantities.

The rate components in Table 4-1 were obtained as follows:

* Sand accumulation rates Vud and Vdd were calculated with algorithms used in Rodriguez
and Dean (2005). Beach profiles measured along different transects were used as input
files, and beach volume changes per meter of shoreline (m3/m) between two consecutive
survey periods were calculated. From these quantities, the volumetric rate of change per
year for the selected beach segment was obtained by multiplying the mean volume change
per meter by the beach length, and dividing the quantity thus obtained by the period
between the surveys (in years). These calculations were repeated for every consecutive
survey interval, and from it, mean annual rates (m3/yr) for each selected long-term
intervals were determined. The same long-term intervals were also used in estimating the
following rate components:

* Accumulation rates Vs, and Vc, which were taken from data supplied by the Jupiter Inlet
District.

* The net littoral drift moving south was assumed to be constant based on a previous study
on Jupiter Inlet by Mehta et al. (1991).

* Transport rate Qs, which was obtained by subtracting from Qnet, the rate of sand entering
the channel Qe, and sand lost to the Ocean Ql.

* The rate of sand entering the inlet Q, was calculated by adding the rate of sand
accumulated in the trap Vst, the rate of sand accumulated in the ICWW Vae, the rate of sand
transport to the northern and southern reaches of the ICWW Qe,, and the rate of sand
transported to the Central Embayment Qc.









* The rate of sand transported southward after leaving the channel Q,s was assumed to be
8.3% of the sediment entering the channel, Qe, based on estimation by Mehta et al. (1991).
This percent was determined in that report from sand transport studies before the south
jetty was extended seaward in 1998. The present percent is likely to be somewhat lower
than the pre-jetty-extension estimate. However, the difference is unknown.

* The rate of sand lost to the Ocean Qz, was also assumed to be 3.8% of sand entering the
inlet Q, (Mehta et al., 1991). This percent was determined from estimates of ebb delta
volume changes prior to 1991. Surveys of the offshore region for years 2000 and 2001
mentioned in Chapter 2, when carried out over a longer time period, e.g., 5 years if done
annually, should enable a reassessment of Qz. Pre-2000 data are not systematic in terms of
survey region covered, and are of poor quality for deciding if the 3.8% value has changed
since 1991.

* Sand transport rate to the ICWW channel north of inlet Q1c, was taken from the report of
Patra and Mehta (2004).

* Sand transport rate towards the Central Embayment Qc was also taken from the report of
Patra and Mehta (2004). Since Qc, and Qc are small relative to the littoral drift, they have
not been evaluated since the rough estimates reported in Mehta et al. (1991), and employed
by Patra and Mehta (2004). However, compilation of dredging history in the ICWW by the
U.S. Army Corps of Engineers (Freda Zifteh, Jacksonville District, personal
communication, December 20, 2006) makes it feasible to revisit these rates, especially
because they can be used to obtain realistic boundary conditions at the north and south
junctions of ICWW and the Loxahatchee estuary. In the present analysis, sediment loads at
these junctions were taken to be nil.

4.3 Data Sources

4.3.1 Types of Data

The following two types of data were used to develop the sand budget:

* Shoreline data, and

* Beach nourishment and dredging data.

These data are described below.

4.3.1.1 Shoreline data

Beach profiles used to calculate shoreline and beach volume changes were obtained from

the Bureau of Beaches and Coastal Systems of FDEP, Palm Beach County website and from JID.

For the selected 30-year long-term period (1975-2004), there were three FDEP surveys each, for









Martin and Palm Beach Counties. Unfortunately, matching FDEP survey dates were not

available for the two counties. Surveys found to be closest in dates were a 1976 survey for

Martin County and 1974 for Palm Beach County, 1982 for Martin County and 1990 for Palm

Beach County, and 2002 for Martin County and 2001 for Palm Beach County (Odroniec, 2006).

Table 4-2 lists the survey dates for each county as well as the beach profile type for each survey.

A beach profile is considered wading if its offshore length is limited by the distance to

which the surveyor can wade or swim, which is typically up to a depth of about 1.5 m. In

contrast, a long profile is taken by a survey vessel and is typically longer than the distance at

which the depth of closure occurs. In the present study, long profiles were used for calculating

updrift and downdrift beach volume changes, which in turn were used to obtain average beach

volume changes for the long-term period 1974-1986 and for 1986-2002. The FDEP surveys were

based on the NGVD29 tidal datum, whereas the JID surveys were based on NAVD88. The

FDEP survey data were converted to NAVD88 by subtracting 0.46 m from the reported

elevations.

The step-by-step calculation procedure was as follows:

* Beach profile data files included nothing, eating (state-plane coordinates) and elevation
(with respect to MLLW, which is 0.8 m below NAVD 88). From these data, each long
profile was represented as distance from the monument and depth at that point.

* At each monument, the area between two consecutive profiles was calculated. This area
gave the unit volume change at that monument between two consecutive surveys. Volume
change calculations began at closest shoreline point for all the surveys and ended at the
depth of closure estimated to be 3.1m by Odroniec (2006).

* The unit volume changes were averaged over the length of the beach to obtain the mean
volume change for that beach. The beach segment north of the inlet covered approximately
8 km from the inlet up to monument R-1 12 in Martin County, and the segment south of the
inlet covered approximately 7 km from the inlet up to R-36 in Palm Beach County. The
choice of R-1 12 was based on two criteria: (1) at that profile there is a slight reorientation
of the shoreline of Jupiter Island such that the shoreline between the inlet and that point
forms a single stretch of a somewhat straight beach; and (2) most of beach nourishment
north of the inlet is believed to have taken place north of R-1 12. Nourishment dates and









volumes are given in Table 4-3. The choice of R-36 was based on separating the stretch of
beach nourishment by JID, which is north of R-36, and by the Palm Beach County, which
is south.

* The volume change for the length of beach was divided by the time in years between two
consecutive surveys to obtain beach volume change per year (Table 4-4).

The JID profiles (taken by Lidberg Land Surveying of Jupiter, Florida), were mainly south

of the inlet, up to R-21 in Palm Beach County. Most profiles began at R-13 and ended at R-17, a

distance of 1.21 km. As a result, the effect of nourishment down to R-36 could not be determined

using these data. The nine surveys are indicated in Table 4-5. Profile data for February 1993 and

March 1994 were provided as blue-printed sheets, and those for the period May 1995 to April

2004 were in the digital format. The blue-printed data were digitized manually.

Figures 4-3 and 4-4 show the along-beach extents for which the beach volume changes

were calculated for the FDEP and JID budgets, respectively.

4.3.1.2 Beach nourishment

Sediment dredged from the JID trap between 1952 and 2006 has been placed as

nourishment on the downdrift beach. Volumes of sand dredged from the trap (including adjacent

channel east of the trap) and the ICWW, and the volumetric amount placed as nourishment are

given in Table 4-6. The combined JID trap and ICWW annual volume is plotted against year in

Figure 4-5. The mean volume is 46,170 m3/yr, and the standard deviation is 47,270 m3/yr,

indicating significant variability in placed quantities.

4.4 Sand Budget Analysis

The first inlet sand budget, for the 1952-88 period, is reported in Mehta et al. (1991).

Components of that budget are given in Table 4-7, and shown pictorially in Figure 4-6. The

budget was based on nourishment volumes from the trap and the ICWW, without knowledge of

synchronous beach volume changes, as beach profiling began only in 1974.









Based on data presented in Tables 4-8, 4-9, 4-10 and 4-11, budgets for four time periods,

two using the FDEP surveys from 1974 to 1986 and from 1986 to 2002, and two using the JID

surveys from 1993 to 1998 and 1998 to 2006 were developed. Since the extension of south jetty

was completed in 1998 (Michael Grella, JID, personal communication), the budget for the 1998-

2006 period can be expected to include effects of the jetty.

Figures 4-7, 4-8, 4-9 and 4-10 pictorially show the budgets for the years 1974-1986 (FDEP

data), 1987-2002 (FDEP data) and 1993-1998 (JID data) and 1998-2006 (JID data), respectively.

As an example, steps are given below for the way in which each component of the budget for

1974-86 was determined in the following way:

* Qnet was taken to be 176,000 m3 per year based on Mehta et al. (1991).

* Q, = Vc + V, + Q,c + Qc = 56,000 m3/yr.

* Ql = 3.8Qne = 7,000 m3/yr.

* Q,= 176000-56000-7000=113,000 m3/yr

* Q,s = 0.083Q, = 5,000 m3/yr.

* Vc = 21,000 m3/yr is the average value for the period 1974-1986, from Table 4-7.

* Vs = 32,000 m3/yr is the average value for the period 1974-1986, from Table 4-6.

* Q, = 2,000 m3/yr from Patra and Mehta (2004).

* Qc = 1,000 m3/yr from Chapter 3 (rounded to the nearest thousand m3).

The 1974-1986 and the 1993-1998 budgets correspond to the periods before the jetty

reconstruction, whereas the 1986-2002 budget covers both pre- and post-jetty construction

periods. Finally, the1998-2006 budget solely includes the period after reconstruction. Beach

volume accretion rates in the 1974-1986 and 1986-2002 budgets are identical; being 1,000 m3/yr

for the north beach, and 7,000 m3/yr for the south beach. Also, the rate of sand entering the inlet

remained nearly constant (45,000 m3/yr for 1974-1986) and (47,000 m3/yr for 1986-2002). There









was a slight decrease in the rate of sand accumulation in ICWW relative to the JID trap, as seen

in Table 4-12. It is uncertain if any statistical significance can be attached to this change. If so,

the cause may be attributed to a steady improvement in inlet management practices (Grella,

1993).

Volume change data for the 1.2 km length of the beach south of the inlet are given in Table

4-13. The unit volume change and total volume change values reflect the difficulty inherent in

choosing any particular period as being representative of a "mean" budget for the beach. For

instance, in the 1993-1998 and the 1998-2004 periods the unit volume change and the total

volume change are both positive, indicating annual accretion. The pre-jetty period is limited to

1993 as the earliest date when JID surveys were first made. If the post-jetty reconstruction period

is increased by two years to 1998-2006, substantial rates of loss of sand are found. Given the

gains during ~5 year long 1993-1998 period and the nearly equal 1998-2004 period, these losses

must be attributed to increased wave activity along the beach of such nature as to cause sand

loss. Since no long term wave gage data in the proximity of the inlet are available prior to 2006,

one must tentatively attribute sand loss to the severity of wave activity in the region since 2004,

which was marked by unusually significant sea storms during Summer and Fall. An inference

one can draw is that sand budgets must be examined each year based on data from the previous

year to track the performance of the inlet. As far as JID's management plan is concerned, it

would appear that the only necessary action should be to maintain the navigable depth and place

the sand on the beach, with minimal losses of sand to the interior region, which is discussed next.

4.5 Sand Budget for Western Zone

Figure 4-11 identifies different components of the budgets for the western zone, which

are given in Table 4-14.

The components of the budget are calculated in the following way:









* Volumetric rate of sand flowing into the Central Embayment from the NW Fork (QNw) is
obtained for Transect F, Table 3-4.

* Volumetric rate of sand flowing into the Central Embayment from the SW Fork (Qsw) is
obtained for Transect H, Table 3-4.

* Volumetric rate of sand flowing into the Central Embayment from the North Fork (QN), is
obtained for Transect D, Table 3-4.

* Volumetric rate of sand flowing out of the Central Embayment flowing across the FECRR
bridge (QF) is obtained for Transect C, Table 3-4.

An analysis of the sand movement in the western zone was also done by Patra and Mehta

(2004). There, the main accumulation feature is the sandy flood shoal. Generally, a flood shoal

develops when an inlet is opened and sediment begins to enter the bay. The effective date of

opening of Jupiter Inlet is 1947, when it was widened permanently by dredging and stabilized

with jetties (Patra and Mehta, 2004). Carr de Betts (1999) estimated the shoal volume in the

Central Embayment to be 7.55x105 m3 in 1983. Much of this volume is believed to have arrived

from the Ocean when the inlet was opened initially, and after the construction of C-18 Canal in

1957/58, a major portion is believed to have come soon thereafter from the SW Fork. The

present rate of accumulation in the Central Embayment was estimated to be of the order of 3,000

m3/yr (Patra and Mehta, 2004). The present rate of transport of sand from the eastern end of the

bay (FECRR bridge) is about 1,200 m3/yr (Chapter 3). The difference, 1,800 m3/yr, arrives from

the NW Fork during river floods (which were not modeled in the present study). Figure 4-12

shows the components of budget for the western zone. During normal, non-flood conditions,

sand load contribution from the NW Fork is negligible (Chapter 3). The North Fork and the SW

Fork do not contribute sand to the embayment.






























Figure 4-1 Approximate boundaries of eastern and western zones for sand budget analysis.


Figure 4-2 Volumetric rate components characterizing sand budget for eastern zone.































Figure 4-3 Length of north beach selected for FDEP budgets.


Figure 4-4 Length of south beach selected for JID budget.









200000

150000

100000

50000
ooo Lu! ;,JLAiW H l,


JV


1952 1962

Figure 4-5 Combined JID trap


1972 1982 1992 2002
Time years )
and ICWW annual dredged volume against year of placement.


Figure 4-6 Components of eastern zone sand budget for 1952-88 (based on Mehta et al., 1991).


I-- Mean |


A ww'r\V\ ~ V I '














































Figure 4-7 Components of eastern zone FDEP sand budget for 1974-1986.


Figure 4-8 Components of eastern zone FDEP sand budget for 1986-2002.


I L)7-1-


Vo u -e I1- qtt




" -tiiil tt R


R )If l





i h o R c111lsiI1 11)I)


11 7 A -


















































Figure 4-9 Components of eastern zone JID sand budget for 1993-1998.


41X









4-0,r.0--
-**Lfa


Figure 4-10 Components of eastern zone JID sand budget for 1998-2006.


I L q







-4































Figure 4-11 Components of sand budget for the western zone.


Figure 4-12 Volumetric sand transport rates in the western zone.









Table 4-1 Components of sand budget for the eastern zone
Quantity Definition
(m3/yr)
Qnet Net littoral drift southward
Vud Beach volume change rate updrift of inlet
Vdd Beach volume change rate downdrift of inlet
Vst Volumetric rate of sand accumulation in the trap
Vec Volumetric rate of sand accumulation in the ICWW channel
Qs Volumetric rate of sand flowing southward bypassing the inlet
Q2 Volumetric rate of sand entering the inlet
Q, Volumetric rate of sand leaving the channel and flowing southward
Q2 Volumetric rate of sediment lost offshore
Qst Volumetric rate of sediment flowing southward from the inlet
Qc Volumetric rate of sand flowing into northern ICWW
Qc Volumetric rate of sand flowing to the Central Embayment


Table 4-2 FDEP surveys for Martin and Palm Beach Counties
County Survey date Profile type
1976 Wading profile every monument; long
profile every third monument
Martin 1982 Wading profile every monument; long
profile every third monument
2002 Wading and long profiles every
monument
1974 Wading profile every monument; long
profile every third monument
Palm Beach 1990 Wading and long profiles every
monument
2001 Wading and long profiles every
monument

Table 4-3 Jupiter Inlet updrift beach nourishment volumes (Odroniec, 2006)
Year Nourishment Source of data
volume
(m3)
1974 741,620 Aubrey and Dekimpe (1988)
1977 366,990 Aubrey and Dekimpe (1988)
1978 649,870 Aubrey and Dekimpe (1988)
1983 108,410 Michael Grella (personal communication, 2006)
1983 764,560 Aubrey and Dekimpe (1988)
1986 116,920 Michael Grella (personal communication, 2006)
1987 1,704,960 Aubrey and Dekimpe (1988)
1995/1996 1,330,330 Beaches and Shores Resource Center










Table 4-4 Volume change rates u drift and downdrift of Jupiter Inlet
Period Vud Vdd
Perio(m /yr) (m /yr)
1974-1986 6,600 7,00
1986-2002 6,900 1,000
Change + 300 +300
Change % + 4.3 + 30


Table 4-5 JID surveys in Palm Beach County
Date Length of survey Original format
February 1993 R-13 to R-17 Sheets
March 1994 R-13 to R-17 Sheets
May 1995 R-13 to R-17 Digital
November 1995 R-13 to R-17 Digital
March 1996 R-13 to R-17 Digital
November 1996 R-13 to R-17 Digital
March 1997 R-13 to R-17 Digital
March 1998 R-13 to R-17 Digital
March 1999 R-13 to R-17 Digital
March 2000 R-10 to R-21 Digital
May 2001 R-10 to R-21 Digital
October 2002 R-10 to R-21 Digital
April 2004 R-13 to R-17 Digital
August 2005 R-13 to R-17 Digital
November 2006 R-13 to R-17 Digital









Table 4-6 Jupiter Inlet trap dredging and placement volumes, 1952-1995
Sand tp Nourishment Nourishment
Sand trap ICWW
Year d g d g from sand trap from other
Year dredging dredging
(i3) (m3) and ICWW sources
(m ) (m )
1952 55070 22920 77990 0
1954 0 45840 45840 0
1956 32090 53480 85570 0
1958 34460 32090 66550 0
1960 34380 34380 68760 0
1962 34380 0 34380 0
1964 93970 0 93970 0
1966 31040 0 31040 0
1968 39810 0 39810 0
1969 0 38580 38580 0
1970 58830 0 58830 0
1972 58450 33460 91910 0
1975 78390 117660 196050 0
1977 71810 0 71810 0
1979 71050 90760 161810 0
1981 57300 0 57300 0
1983 45840 23910 69750 0
1985 58060 0 58060 0
1986 0 17280 17280 0
1987 50040 0 50040 0
1988 52950 66470 119420 0
1990 64940 0 64940 0
1991 43430 0 43430 0
1992 0 106200 106200 0
1993 47000 0 47000 0
1994 54640 0 54640 0
1995 55010 84420 139430 461460
1996 24100 0 24100 0
1998 64940 0 64940 0
2000 42940 27180 70120 0
2001 63340 49530 112870 0
2002 33620 0 33620 477500
2004 45840 84040 129880 0
2005 59590 0 59590 0
2006 53860 0 53860 0
a NA Not available.
b Source of additional sand not known.









Table 4-7 Annual sand transport rates near Jupiter Inlet, 1952-1988 (Mehta et al., 1991).
Transport from/to Volumetric rate
(m3/yr)
Net southward littoral drift (Qnet) 176,000
Entering the channel from littoral drift (Q,) 46,000
Bar-bypassed around the inlet (Q,) 128,000
Volumetric rate of sand accumulation in the ICWW (Ve,) 10,000
Volumetric rate of sand accumulation in the trap (Vt) 23,000
Tidally bypassed by entering and then leaving the channel (Qs) 4,000
Ejected from the channel to offshore by ebb flow (Ql) 5,000
Transported to ICWW channels north of inlet (Qc) 3,000
Transported to Central Embayment (Qc) 2,000

Table 4-8 Annual sand transport rates in the eastern zone for 1974-1986 FDEP budget.
Transport from/to Volumetric rate
(m3/yr)
Net southward littoral drift (Qnet) 176,000
Entering the channel from littoral drift (Q)) 56,000
Bar-bypassed around the inlet (Qs) 113,000
Volumetric rate of sand accumulation in the ICWW (V,) 21,000
Volumetric rate of sand accumulation in the trap (Vst) 32,000
Tidally bypassed by entering and then leaving the channel (Q,) 5,000
Ejected from the channel to offshore by ebb flow (Q) 7,000
Transported to ICWW channels north of inlet(Q,c) 2,000
Transported to central embayment(Qc) 1,000
Beach volume change rate updrift of inlet (Vud) 1,000
Beach volume change rate downdrift of inlet (Vdd) 7,000


Table 4-9 Annual sand transport rates in the eastern zone for 1986-2002 FDEP budget
Transport from/to Volumetric rate
(m3/yr)
Net southward littoral drift (Qnet) 176,000
Entering the channel from littoral drift (Q,) 54,000
Bar-bypassed around the inlet (Qs) 115,000
Volumetric rate of sand accumulation in the ICWW (Ve,) 17,000
Volumetric rate of sand accumulation in the trap (Vst) 34,000
Tidally bypassed by entering and then leaving the channel (Q,s) 5,000
Ejected from the channel to offshore by ebb flow (Q)) 7,000
Transported to ICWW channels north and south of inlet (Q,c) 2,000
Transported to Central Embayment (Qc) 1,000
Beach volume change rate updrift of inlet (Vud) 1,000
Beach volume change rate downdrift of inlet (Vdd) 7,000









Table 4-10 Annual sand transport rates in the eastern zone for 1993-1998 JID sand budget
Transport from/to Volumetric rate
(m3/yr)
Net southward littoral drift (Qnet) 176,000
Entering the channel from littoral drift (Qe) 58,000
Bar-bypassed around the inlet (Q,) 111,000
Volumetric rate of sand accumulation in the ICWW (Ve,) 14,000
Volumetric rate of sand accumulation in the trap (Vt) 41,000
Tidally bypassed by entering and then leaving the channel (Qs) 5,000
Ejected from the channel to offshore by ebb flow (Q') 7,000
Transported to ICWW channels north and south of inlet(Qc) 2,000
Transported to Central Embayment(Qc) 1,000
Beach volume change rate downdrift of inlet (Vdd) 4,000


Table 4-11 Annual sand transport rates in the eastern zone for 1998-2006 JID sand budget
Transport from/to Volumetric rate
(m3/yr)
Net southward littoral drift (Qnet) 176,000
Entering the channel from littoral drift (Qe) 61,000
Bar-bypassed around the inlet (Qs) 107,000
Volumetric rate of sand accumulation in the ICWW (Ve,) 18,000
Volumetric rate of sand accumulation in the trap (Vs,) 40,000
Tidally bypassed by entering and then leaving the channel (Q,s) 5,000
Ejected from the channel to offshore by ebb flow (Q)) 7,000
Transported to ICWW channels north and south of inlet(Q,c) 2,000
Transported to Central Embayment(Qc) 1,000
Beach volume change rate downdrift of inlet (Vdd) -9,000


Table 4-12 Rates of accumulation in JID sand trap and ICWW
Rate of Rate of
ICWW rate
P. accumulation accumulation r
Penod as a fraction of
in JID trap in ICWW
(m /yr) (m /yr) JID
1952-1988 27,000 16,000 0.6
1974-1986 32,000 21,000 0.6
1986-2002 34,000 17,000 0.5









Table 4-13 Jetty pre- and post-extension volume changes on 1.2 km of south beach
Unit volume Total volume
Period Jetty change change
Status (m3/yr m) (m3
1993-1998 Pre-extension +2.92 +17,526
1998-2004 Post-extension, pre-storms +13.16 +126,310
1998-2006 Post-extension, post-storms -7.46 -71,689

Table 4-14 Definitions of components of western zone sediment budget.
Component Definition
QNW Volume rate of sediment flowing into the
Central Embayment from the
North West Fork
Qsw Volume rate of sediment flowing into the
Central Embayment from the
South West Fork
QN Volume rate of sediment flowing into the
Central Embayment from the
North Fork
QF Volume rate of sediment flowing into the
Central embayment across the
FECRR bridge.
Vc Volumetric rate of accumulation in the
Central Embayment


Table 4-15 Annual mean sand transport rates in the western zone.
Volumetric rate
Transport from/to or accumulation (3/yr)
(m /yr)
From Northwest Fork (QNw) 1,800
From Southwest Fork (Qsw) 0
From North Fork (QN) 0
To Central Embayment past FECRR bridge (QF) 1,200
Accumulation in Central Embayment (Vc) 3,000









CHAPTER 5
SUMMARY AND CONCLUSIONS

5.1 Summary

Due to the presence of Jupiter Inlet, the potential for beach erosion has always existed

along the downdrift beach, especially since the late 1940's when the inlet navigation was

stabilized by robust jetties and sand dredging from the channel. The management of the sand

resources within the inlet area is dependent on rates of sand inflow, outflow and accumulation

(or erosion). The objective of this study was to determine a new sand budget for the inlet area,

including its inner bay called the Central Embayment. Tasks undertaken to meet this objective

were: (1) collection of current velocity and suspended sediment concentration data for sand

moving within the inlet channel, (2) use of a numerical model along with collected data to

estimate sand loads at selected transects in the inlet channel and the Central Embayment, (3)

analysis of data on beach profiles, sand accumulation and sand transfer in the inlet area, and (4)

development of sand budgets for the inlet and the Central Embayment.

5.2 Conclusions

Based on the above mentioned tasks, the following conclusions can be derived:

* The peak velocity of the water that flows in was found to be approximately 35% more than
the velocity of water that flows out, which as result causes more sediment to flow in to the
channel than out of it. This observation is supported by calculations of bed shear stresses
from the velocity measurements, which were higher during flood flow than during the
subsequent ebb flow.

* The majority of sediment supply from the seaward end of the inlet is as suspended load.
Suspended sediment mobility just offshore of the mouth is dependent on wave-induced
bottom stresses (Appendix A), as can be (partially) verified from the fact that the
movement of sand from the beaches increased significantly between 2004 and 2006 due to
storm wave activity.

* The movement of sand in the western half of the Central Embayment is low because of
low flow velocities. However, sand does move into the Central Embayment at its eastern
end under the FECRR bridge at the rate of about 1,200 m3/yr. This value is in order of
magnitude agreement with 1,000 m3/yr estimated by Patra and Mehta (2004).









* The increase in the frequency of dredging in the sand trap has resulted in a slight decrease
in the volume of sand deposition in the ICWW relative to the JID trap. The ICWW-to-trap
ratio of annual volume dredged decreased from 0.6 during 1974-1986 to 0.5 during 1986-
2002.

* The 8 km long stretch of the beach north of the inlet has remained stable since 1974,
gaining only 1,000 m3/yr, a negligible amount during 1974-2002. The south beach, of 7 km
length, has gained 7,000 m3/yr during the same period.

* Unit volume change and total volume change values for the 1.2 km length of the beach
south of the inlet reflect the difficulty inherent in choosing any particular period as being
representative of a "mean" budget for the beach. For instance, in the 1993-1998 and the
1998-2004 periods the unit volume change and the total volume change are both positive,
indicating annual accretion. The pre-jetty period is limited to 1993 as the earliest date
when JID surveys were first made. If the post-jetty reconstruction period is increased by
two years to 1998-2006, substantial rates of loss of sand are found. Given the gains during
-5 year long 1993-1998 period and the nearly equal 1998-2004 period, these losses must
be attributed to increased wave activity along the beach of such nature as to cause sand
loss. Since no long-term wave gage data in the proximity of the inlet are available prior to
2006, one must tentatively attribute sand loss to the severity of wave activity in the region
since 2004, which was marked by unusually significant sea storms during Summer and
Fall.

* An inference one can draw from the above observations is that inlet sand budget must be
examined each year based on data from the previous year to track the performance of the
inlet.

* Most of the erosion at the beach in the vicinity of the inlet (FDEP monuments R-13 to R-
17) appears to be due to the immediate presence of the inlet. For instance, the shoreline at
location R-15 has oscillated between 74 m to +63 m during 1993-2006, relative to
shoreline position in February, 1993 (Appendix B). The same beach segment is also the
immediate beneficiary of nourishment provided by hydraulic transfer of sand from the
inlet.

5.3 Recommendations for Further Work

In order to increase the accuracy of future sediment budget analyses, the following

recommendations should be considered:

* Beach surveys should cover the R-13 to R-21 reach annually. R-10 through R-12 may be
surveyed every three years. Consideration must be given to profiling every 500 ft (152 m)
between R-14 and R-16, as opposed to the present 1,000 ft (304 m) distance.

* For applying the technique described in Appendix C to assess shoreline changes south of
the inlet from aerial images, the trajectory of excursion of the camera must remain










constant, i.e., its setting must not be changed for the time when the observations are being
made.









APPENDIX A
WAVE-INDUCED SAND MOBILITY

A.1 Wave Data

Waves combined with a current increase the effective bed shear stress over merely current

flow. This may increase sediment mobilization and thus transport into or out of Jupiter Inlet.

Thus, an estimation of how frequently waves mobilize sediment at the inlet mouth can provide

an indication of their importance in making additional sediment available for transport, over and

above transport due to tide.

This analysis is carried out in the following two parts:

* Prediction of bed shear stresses for specified waves and currents.

* Estimation of how these stresses affect sand mobilization.

For the stress computations, the measured tidal currents were assumed to be applicable to

the mouth area.

There are no wave gauges in the immediate vicinity of Jupiter Inlet. However, good

records are available from the closest nearshore gauge at Melbourne Beach. Because waves

arriving at Jupiter from the southeast are sheltered somewhat by the Bahamas Bank, the

Melbourne Beach record can be expected to indicate slightly larger wave heights than at Jupiter

Inlet. However, the general wave climate along the Melbourne Beach to Jupiter Inlet coast can

be considered to be similar, and the Melbourne Beach gauge is believed to be a reliable source of

wave information for this stretch of the beach. Thus, data from this gauge will used it to calculate

wave-induced orbital velocities for bed shear stress estimation. To estimate the sediment

transport regime from bed shear stress, the well known Shields criterion will be used.


Figure A-i shows measured wave records from 2003-2005, which includes several

hurricane events. The record is almost complete and can be expected to give a good picture of










the overall wave climate. Calculated statistics of wave height and period are shown in Figure A-

2. These show a moderate wave climate, with most probable wave heights around 0.6 m and 0.15

Hz frequency (7 s period). These values are in agreement with other estimates of wave

characteristics on Florida's Atlantic Coast. Wave properties were then transformed from the 8 m

depth contour, where measurements were taken, to the representative depth of 3 m at the inlet

mouth, taking into account wave shoaling and dissipation (Prof Andrew Kennedy, personal

communication).


2003 2004 2005
4 -

03 .r : :
"- : !i. i *

LII


Time (years)

Figure A-i Measured time-series of significant wave height off Melbourne Beach in 8 m depth.




20,

E 15-

B";



height of around 0.6 m and frequency of 0.15Hz (7 s wave period).
0- -15



Peak wave Frequency (Hz) Significant Wave HeigM (nm)
Figure A-2 Joint probability density for wave height and frequency in 8 m, showing typical wave
height of around 0.6 m and frequency of 0.15Hz (7 s wave period).









A.2 Sediment Movement


The Shields parameter is defined as


pg(S- )d (A.1)

where Tb is the bed shear stress, g is gravitational acceleration, p is the fluid density and S and d

are the specific gravity and median diameter d50 of the sediment, respectively. For low Shields

parameters, there is no sediment mobilization (or transport), and the amount of mobilized

sediment increases with increasing Y. The bed shear stress will be estimated for combined wave-

current flows using use the method of Soulsby et al. (1988). In addition to the sediment

parameters, this method requires basic wave and current characteristics.

To transform measured wave characteristics at 8 m to the 3 m depth near the inlet mouth, a

simple one-dimensional model was used


S(ECg) = (A.2)

where E is the wave energy, Cg is the shoreward component of the wave group velocity and Ed is

the breaking-induced dissipation, calculated using the method of Thornton and Guza (1982).

This model was run for all relevant combinations of wave height and period, using a

characteristic bed slope of 0.020. Knowing the frequency of occurrence for each offshore wave

condition, the wave climate at 3 m depth was determined as shown in Figure A-3. Note the

maximum significant wave height at this depth does not exceed around 1.9 m, as larger offshore

waves will break and reduce wave heights to this value.














0.8 /

2 0.6
a_ /
S 0.4
E //
d 0.2

0
0 ------ ---------------------------
0 0.5 1 1.5 2 2.5
Significant Wave Height (m)
Figure A-3 Cumulative probability that significant wave height will be less than a given value at
depth 3 m.


The statistical distribution of wave heights and periods at this location was then used to

estimate the statistical distribution of bed shear stress Tb over a typical tidal cycle with peak flood

flow velocity of 1 m/s using the method of Soulsby et al. (1988). This bed shear stress was then

used to calculate the statistical distribution of Shields parameter using assumed value of

"suspendable" sediment diameter dso = 0.2 mm and specific gravity S = 2.65.



The Shields parameters were then used to estimate the sediment transport regime using the

criteria in Table A-1, and the statistical probabilities were used to estimate their frequencies of

occurrence. As seen in Table A-1 and Figure A-4, waves and currents are large enough that there

are almost no occasions when sediment is not mobile. Eight percent of the time, there will be

minor bed load transport which probably contributes little to the overall net transport; larger bed

load transport with some suspended load is likely around 23% of overall conditions, while there

is strong bed load and suspended load the remainder of the time, around 69%. An examination of

Figure A-4 further shows that very high Shields parameters of Y > 2 are likely 12% of the time,

which would further increase sediment mobilization and assist in transporting sediment into the

inlet.











Table A-i Types of sediment transport and frequency of occurrence at the inlet in 3 m depth
Shields Sediment transport behavior Frequency of
parameter occurrence
Wave- Current
Current Only
(%) (%)
Y < 0.05 No sediment motion 0 17
0.05 < Y < 0.5 Some bed load transport, rippled beds 8 49
0.5 < Y < 1 Bed load and some suspended load, rippled beds 23 34
Y > 1 Strong bed load and suspended load, sheet flow 69 0




0.8 (b) (c) (d)

0 0.6 /
0.4

S0.2

0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Shields Parameter
Figure A-4 Cumulative probability that Shields parameter will be less than a given value for
combined wave-current flow; (b) Some bed load transport, rippled bed (c) bed load
and some suspended load, rippled bed; (d) Strong bed load and suspended load, sheet
flow. The category of no sediment motion is to the left of dashed line in category (b).


These large bed shear stresses may be compared to the current-only bed shear stresses

induced from pure tidal motion. Figure A-5 and Table A-i show the Shields probability

distributions for pure current flow, and may be compared to results for combined wave-current

motion in Figure A-4. Sediment mobilization decreases dramatically, with no occasions of strong

sediment mobilization with Y > 1, and 17% occurrence of no sediment mobilization at all. Thus,

sediment transport into the inlet will be increased significantly by waves mobilizing sediment at

the inlet mouth. This mobilized sediment is likely to be deposited further in the inlet as the wave











climate decreases, e.g., in the sand trap. The gross sediment mobilization (Figure. A-6) is


obtained using the following equation


= 3
Q = ((S- 1)gd)2.d.8.(y- vm)2.b


(A.3)


where b is the width of the channel.


1

0.8
(0
-Q
2 0.6

S0.4

d0.2


0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Shields Parameter

Figure A-5 Cumulative probability that Shields sediment mobility parameter will be less than a
given value for pure tidal current flow. Labels are identical to Figure A-4.






0S 0.03
E
c 0.025 -
S*
0.02 -

10.015 i ; : : i : .



0) 0.005
S 0
CD 2003 2004 2005



Figure A-6 Gross sediment mobilization time-series for 2003-2005 at Jupiter Inlet mouth.












APPENDIX B
SHORELINE AND BEACH VOLUME CHANGES


This appendix includes shoreline changes and beach volume changes obtained from beach


profiles at monuments R-13 through R-17. Figures B-1 through B-5 covering profiles from


February 1993 to March 2006, are based on data provided by JID (and taken by Lidberg Land


Surveying of Jupiter, Florida), Figures B-6 through B-10, including profiles from July 2001 to


August 2005, were taken from the Palm Beach County website (http://www.co.palm-


beach.fl.us/erm/enhancement/beachreports.asp). Unit volume changes and the shoreline changes


between consecutive surveys are given in Figures B-11 and B-12, respectively. Figures B-13


through B-17 show the shoreline position for R-13 through R-17.


--Feb-93
- Mar-94
May-95
Mar-96
- Mar-97
- Mar-98
- Mar-99
- Mar-00
May-01
Oct-02
Apr-04
Aug-05
Nov-06


Figure B-1 JID Beach profiles at R-13.


0 200 400 600 800 1000 1200 1400 1600 1800 2000
Distance (m)
























1o
5





0

E r< r



-5 -











15
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Distance (m)



Figure B-2 JID Beach profiles at R-14.


0 200 400 600 800 1000
Distance (m)


1200 1400 1600 1800


--Feb-93
- Mar-94
May-95
Mar-96
- Mar-97
- Mar-98
--Mar-99
--Mar-00
May-01
Oct-02
Apr-04
Aug-05
Nov-06


- Feb-93
- Mar-94
May-95
Mar-96
- Mar-97
- Mar-98
- Mar-99
- Mar-00
May-01
Oct-02
Apr-04
Aug-05
Nov-06


Figure B-3 JID Beach profiles at R-15.





















































0 200 400 600 800 1000
Distance (m)


1200 1400


1600 1800


Figure B-4 JID Beach profiles at R-16.


- Feb-93
- Mar-94
May-95
Mar-96
- Mar-97
- Mar-98
--Mar-99
--Mar-00
May-01
Oct-02
Apr-04
Oct-05
Nov-06


15F,























.1 -. :

r,,1 4r.

10



..= --^ r,1 j i,,.,
jrl i. ,iii
-5 '" ,-,Ill
., 1.11,





-10





15
0 200 400 600 800 1000 1200 1400 1600 1800
Distance (m)



Figure B-5 JID Beach profiles at R-17.


















4


2


0



-- Jul-01
f --Jul-02
S-4 Sept-03
Jul-04
Aug-05
-6


-8


-10


-12


14
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Distance (m)




Figure B-6 County beach profiles at R-13.


















4



2



0



-2 -2



S-4



-6



-8



-10



12
0 200 400 600 800 1000 1200 1400
Distance (m)


--Jul-01
--Jul-02
Sept-03
Jul-04
- Aug-05


1600 1800


Figure B-7 County beach profiles at R-14.

















































0 200 400 600 800 1000 1200
Distance (m)


--Jul-01
- Jul-02
Sept-03
Jul-04
-Aug-05


1400 1600


Figure B-8 County beach profiles at R-15.



















6


4


2


0



S-2


0 -4


-6 -


-8


-10


-12


14
0 200 400 600 800 1000 1200 1400
Distance (m)


--Jul-01
--Jul-02
Sept-03
Jul-04
- Aug-05


1600 1800


Figure B-9 County beach profiles at R-16.


--Jul-01
-2002
Sept-03
Jul-04
- Aug-05


0 200 400 600 800 1000 1200 1400 1600 1800
Distance (m)


Figure B-10 County beach profiles at R-17.

















Feb'g3-Mar94


60
Mar@4-Mayg6


May'r5-MarOB


20 ^ff. '* ^Maro96-Mar'o



20
Seo -- Mar-Mar





-Apryo--Jul'04




--C
a)- Jul'04-OOg'

-4 --- ---------------------------------------------- -------eo
4 .S.epo-Apro4
--Apr,04-Jul'04
-o"\\,. ---Jul'04-AuB'05

Aug'- -Novo6



-100
13 14 15 16 17
Monument



Figure B- 1 Shoreline changes for 1993-2006 (R-13 to R-17).


400



goo


-Feb93-Mar'94
200 Mar'94-May'95
N May'5-Mar'96
Mar'96-Magr97
S100 --Mar'97-Ma98

S- Mar'a-Mar99
C .- -.__ -., --Mar'00-May'01

S MayO1 -JuOl
-----Jul 01-Jult'O2
Jul02 -0c02
> -100 ----- Oc'02-Sap'03
-- Sep03-Apr'04
-Apr0O4-Ju'04
-200 --Jul4-4Aug'05
Aug'05-Nov'06


-300



-400
13 14 15 16 17
Monuments



Figure B-12 Unit volume changes for 1993-2006 (R-13 to R-17).














200
R-13

180


160


140
E

S120
E

100
E

S80


60


40


20


0
Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07
Date


Figure B-13 Shoreline position at monument R-13 starting February, 1993.



200
R-14
180


160


140

E




0
20
u 80


60


40


20


0
Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07
Date


Figure B-14 Shoreline position at monument R-14 starting February, 1993.













200
R-15
180

160


E

120

100

80




40

20

0
Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07
Date

Figure B-15 Shoreline position at monument R-15 starting February, 1993.



200
R-16
180

160

140

| 120 \

100
E

80
-


S60 ,-r

40

20

0
Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07
Date

Figure B-16 Shoreline position at monument R-16 starting February, 1993.

























120


E -
















Date
F 80


60


40


20


0 .
Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07
Date


Figure B-17 Shoreline position at monument R-17 starting February, 1993.









APPENDIX C
ESTIMATION OF SHORELINE CHANGE FROM AERIAL IMAGERY

Rectification of aerial photographs involves the establishment of ground control points that

link each image to its corresponding aerial coverage on a digital orthophoto quarter quad

(DOQQ), which serves as the base map. Points are chosen on the image that can be matched to

points on the DOQQ. Road intersections and other cultural features are preferred as reference

points rather than natural features. However, in many cases cultural features are absent and

features such as trees, shrubs, and the edges of water bodies are used. Where possible, points are

evenly spaced across the image, with special emphasis on the edges of the image, and on areas

near to the shoreline.

Thus, for calculating the shoreline changes south of Jupiter Inlet, aerial imagery was used.

For an illustration of the method, we will consider Figures. C-l and C-2, which show images for

November 30, 2004 (10:10 am) and April 07, 2006 (1:15 pm), respectively, as obtained from a

camera mounted on the Ocean Trails condominium south of the inlet. The rectangle marks the

area which had control points. Figures C-3 and C-4 are the images showing the control points

north and south of the camera, respectively, on the south beach. Table C-l gives the coordinates

(latitudes and longitudes) and elevation (meters above sea level) for the control points shown

pictorially in Figures. C-3 and C-4.

After the ground control points were established near the beach, two images were rectified

using a computer program developed by Prof. Andrew Kennedy. Ten of the points from Figure

C-4 were selected for analysis, as rectification required at least 8 of the 10 points. After

rectification was complete, the image was made semi-transparent and overlain on the DOQQ.

Figure C-5 show plots for shoreline changes prepared by comparing the two images. Figures C-6

and C-7 give the tidal data for the two dates when the images were taken. These indicate that the










images were obtained at different stages of tide; the 2004 image was at high tide and the 2006

image at low tide. Given this discrepancy, the shorelines in Figure C-5, both of which have the

same orientation, cannot be compared with regard to beach width.
.1q '* j .-4.* 1 ,iti r:.l ,, .. ,,. : ., 'I** "' *' i, ,


Figure C-l Shoreline on November 30, 2004 (10:10 am).


_"'-r~r*ar~flWUPIplrflfl. ..;;


Figure C-2 Shoreline on April 07, 2006 (1:15 pm).

































Figure C-3 Beach imaging control points north of camera.


Figure C-4 Beach imaging control points south of camera.


:.EI

CI~'~;~;~s~.LC~









Table C-1 Coordinates and elevations of the control points.
Points Latitude Longitude Elevation (m)
1 2656.422593 8004.282727 3.101
2 2656.424095 8004.284790 3.591
3 2656.424352 8004.283473 3.599
4 2656.429943 8004.284474 2.922
5 2656.445124 8004.293226 2.705
6 2656.414737 8004.272036 5.035
7 2656.416346 8004.268788 5.031
8 2656.417721 8004.269640 5.030
9 2656.416361 8004.272451 5.046
10 2656.273841 8004.221734 4.480
11 2656.272311 8004.221251 4.974
12 2656.267373 8004.221245 4.841
13 2656.263371 8004.222644 4.360
14 2656.263723 8004.220953 6.945
15 2656.265210 8004.221443 6.965
16 2656.269529 8004.216125 6.948
17 2656.272940 8004.207913 5.328
18 2656.273786 8004.204519 1.766
19 2656.245712 8004.211376 4.846
20 2656.230963 8004.206619 5.110
21 2656.218549 8004.197241 7.168
22 2656.221408 8004.184580 3.848
23 2656.216380 8004.213872 0.512
24 2656.188789 8004.191339 5.839
25 2656.168808 8004.173882 4.894
26 2656.356848 8004.239158 3.733
27 2656.356970 8004.242266 4.362
28 2656.354013 8004.246407 4.024
29 2656.352355 8004.247356 3.914
30 2656.309336 8004.242825 46.529













Shore line position in year 2004 and 2006


-O--Year 2004
--*--Year 2006


2.889



2.888



2.887


2, 885





2.884-



2 883 -



2.882 I
2.9238 2.924 2.9242 2.9244 2.9246 2.9248 2.925 2.9252 2.9254
eastings



Figure C-5 Comparison between shoreline positions in 2004 and 2006.


2.9256
x105


Jupiter Inlet, U.S. Highway 1 Bridge, Florida
1-11-29 2004-11-30 2004-11-30 2004-11-30 2004-11-30 2004-12-01
5 PM EST 4:58 AM EST 11:09 AM EST 5:35 PM EST 11:07 PM EST 5:39 AM EST


2004-12-01 2004-12-01
11:50 AM EST 6:18 PM EST


11 1 1 2 3 4 5 .. 10 11 1 1I 3 5 *. I 1 1 3 4 5 ,. 8 9 10 11 L- 1 3 4 5 L

Figure C-6 Tide on November 30, 2004 corresponding to Figure C-1 (2.25 ft above MLLW).















)006-04-06 2006-04-07
L:28 PM EDT 5:41 AM EDT




2 ft



1 ft-



I t'T


Jupiter Inlet, U.S. -i;1l-.i., 1 I E.-1e, Florida
2006-04-07 2006-04-07 _',:-,,J-,,: 2006-04-08
12:14 PM EDT 5:58 PM EDT 12:30 AM EDT 6:35 AM EDT


2006-04-08 2006-04-08
1:07 PM EDT 6:54 PM EDT


S11I 1 2 3 4 5 E ,1 I 11 ; 1 3 4 5 ,' 1. 1 4 5 6 3 ? 1' 11i I 1 : 4 5 6 3



Figure C-7 Tide on April 7, 2006 corresponding to Figure C-2 (0.5 ft above MLLW).









APPENDIX D
BASIS FOR THE LENGTH OF SOUTH JETTY EXTENSION

D.1 Introduction

The purpose of extending the south jetty was two-fold: (1) to improve conditions for

navigation in the channel, and (2) to increase the retention time of sand placed on the south

beach.

Improvement in navigation would mean: (a) streamlining flood and ebb tidal flows, (b)

reducing the impact of oblique waves on vessels, and (c) improving the self-cleaning capacity of

flow in order to maintain channel depth over the ebb delta.

Increase in the retention time of sand was to be achieved by: (a) increasing beach

protection from storm waves from the northwest, (b) reducing the return flow of sand into the

inlet.

For the present study the second purpose is relevant, as it pertains to the efficacy of the

sand placement protocol before and after jetty reconstruction. The placement of any structure

perpendicular to the shoreline, such as a groin or a jetty, disturbs the littoral sand drift and causes

erosion downdrift of the structure. It follows that longer the structure the deeper the erosion.

There is equivalent accretion on the updrift side. In Figure D-1 the progression of downdrift

erosion and updrift accretion are modeled at a shoreline at which a shore-normal structure is

placed. The structure and wave conditions modeled were representative of conditions at Jupiter

Inlet. Erosion is seen to extend in depth and distance with years. After a very long time and

theoretically, the downdrift shoreline can be expected to recede by a distance equal to the

protruding length of the structure. Accordingly, this modeling exercise can be used to show that

lengthening the structure will reduced the rate of progression of erosion, but that the depth of

erosion will increase. This is an important observation as it shows that in the final selection of










the length of the structure, these two aspects of beach erosion (depth versus distance) must be

balanced.

Two equal-length and parallel jetties at a narrow inlet (such as Jupiter) can be thought of as

a single structure impacting the shoreline as in Figure D-1. Once the shoreline is modified by the

jetties, the "no-inlet" shoreline can be theoretically determined by modeling shoreline changes

following jetty construction. In practice one can also make a judgmental choice based on the

known orientations of the shorelines far from the inlet.

300
Sand drift i
200 ..

100
S30 yr 10yr 20 yr





-200
I5y 30 yr



-200 .............. .. ..Infinite tim e

-300
-40000 -20000 0 20000 40000
Distance alongshore (ft)


Figure D-1 Simple model-based results of progression of erosion and accretion as a result of a
shore-normal structure.

Since the main agent for downdrift shoreline erosion is wave action, in order to reduce the

rate of erosion a sheltered area must be created. At Florida's east coast inlets sand drift occurs

northward in summer and southward in winter as the wave direction changes from NW to SW.

The annual net drift is southward due to the higher energy waves in winter. Nevertheless,

because the drift occurs in two directions, downdrift erosion rate can be reduced by extending

and reorienting the south jetty. However, erosion cannot be stopped entirely unless other









measures, such as beach nourishment, are taken. Nourishment is essential to maintain the

downdrift shoreline in the "shadow" zone of the jetty.

To revise the configuration of the jetties, tests were carried out in a fixed-bed hydraulic

model at the Coastal and Oceanographic Engineering laboratory of the University of Florida. A

summary of these tests is given in DelCharco (1992) and results are discussed in Mehta et al.

(1992) for an assessment of the downdrift impact of the modified jetties relative to then existing

configurations. This assessment was based on quantitative criteria related a balance between the

wave-sheltering effect of the jetties and their beach erosion potential. The longer the jetties, the

greater the sheltering effect of the (immediately) downdrift region against severe northeasters.

However, this would also mean greater long-term recession of the shoreline. A shelter was

desired by JID against episodic erosion immediately downdrift of the inlet. It was feared that

"flanking" of the narrow barrier could take place, i.e., breaching of the barrier island would

occur just south of the south jetty. Severe erosion at the site of a parking lot close to the south

jetty did occur at the end of October, 1991.

D.2 Outcome of Hydraulic Modeling Tests

Hydraulic model tests indicated that any significant extension of the north jetty would

further divert the net littoral drift away from the south beach. Therefore, only extensions of the

south jetty in various configurations were considered. The configuration most likely to succeed

was one including a linear extension followed by a curved extension (Figure D-2).