Citation
Beach nourishment design

Material Information

Title:
Beach nourishment design consideration of sediment characteristics : prepared for Office of Beaches and Coastal Systems, Florida Department of Environmental Protection ...
Series Title:
UFLCOEL-2000002
Creator:
Dean, Robert G ( Robert George ), 1930-
Florida -- Office of Beaches and Coastal Systems
Place of Publication:
Gainesville Fla
Publisher:
Coastal & Oceanographic Engineering Program, University of Florida
Publication Date:
Language:
English
Physical Description:
vii, 41 leaves : ill. ; 28 cm.

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Subjects / Keywords:
Beach nourishment ( lcsh )
Sand -- Sampling -- Mathematical models ( lcsh )
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government publication (state, provincial, terriorial, dependent) ( marcgt )
bibliography ( marcgt )
non-fiction ( marcgt )

Notes

Bibliography:
Includes bibliographical references (leaves 40-41).
General Note:
"February 23, 2000."
Statement of Responsibility:
prepared by Robert G. Dean.

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University of Florida
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University of Florida
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
49575830 ( OCLC )

Full Text
UFL/COEL-2000/002

BEACH NOURISHMENT DESIGN: CONSIDERATION OF SEDIMENT CHARACTERISTICS by
Robert G. Dean

February 23, 2000
Prepared for: Office of Beaches and Coastal Systems Florida Department of Environmental Protection Tallahassee, Florida




BEACH NOURISHMENT DESIGN:
CONSIDERATION OF SEDIMENT CHARACTERISTICS
February 23, 2000
Prepared for:
Office of Beaches and Coastal Systems
Florida Department of Environmental Protection
Tallahassee, Florida
Prepared by:
Robert G. Dean
Civil and Coastal Engineering Department
University of Florida
345 Weil Hall, P. 0. Box 116580 Gainesville, Florida 32611-6580




EXECUTIVE SUMMARY

Two issues relevant to beach nourishment design are addressed in this report. The first is a rational approach to characterizing the composite sand characteristics of the pre-nourished (native) beach. Given the mean and sorting (standard deviation) of each of several samples across the active native profile, a method is presented for calculating the mean and sorting of the composite of the samples. These characteristics provide a rational basis for comparison against candidate nourishment sediments.
The second issue relates to the equilibrated beach profile resulting from a nourishment sediment characterized by a mean and sorting. Previous methods have considered the nourishment material to be characterized by a single size (usually the median) which is equivalent to a sorting value of zero. These previous methods provide reasonable results for the cases in which the nourishment sediments are of the same approximate size or coarser than the native. However, if the nourishment sediments are substantially smaller than the native and have reasonable sorting values (> 0.5), these results underpredict substantially the additional dry beach width. The explanation is that some of the sediments in the distribution will be as coarse as and coarser than the native and will thus contribute to a steeper profile which yields a greater additional dry beach width than for a single sized nourishment sediment with the same mean. For nourishment sediments with mean sizes greater than the native, non-zero sorting of the nourishment sediments reduces the additional dry beach width relative to nourishment sediments with a single size.
For nourishment sediments of different sizes than the native, the ratio of additional dry beach width to volume density (volume per unit beach length) of the nourishment sediments varies with volume density. For sediments coarser than the native, this ratio increases with decreasing volume density and vice versa for sediments finer than the native. Thus for the idealized case of nourishment on a long straight beach, the total dry beach plan area increases and decreases for sediments coarser and finer, respectively, than the native as the nourishment volume density decreases due to nourishment spreading out to the adjacent beaches. Examples are presented to illustrate the effect for conditions reasonably representative of a nourishment project in Florida for a time period of 20 years and three nourishment sediments. The changes in total plan area over the 20 year period ranged from -22% for the finer sediments up to +32% for the coarser sediments and were relatively small compared to the effects of the differences in total plan area due to different nourishment grain sizes. For a native grain size of 0.2 mm and zero sorting and a mean nourishment grain size of 0.275 mm and a sorting value of 0.5, the ratio of plan area relative to the case of nourishment with compatible sediments is 1.84 after 20 years. For the same native grain size and a nourishment sediment with a mean size and sorting of 0. 14 mm and 0.5, respectively, the corresponding ratio is 0.4 1.




TABLE OF CONTENTS
EXECUTIVE SUM MARY .................................................... ii
LIST OF FIGURES .......................................................... iv
LIST OF TABLES .......................................................... vii
I INTRODUCTION ...................................................... 1
2 BACKGROUND ....................................................... 1
2.1 The Phi Scale for Sediment Size Characterization ...................... 1
2.2 Earlier Methodologies of Accounting for Sediment Sizes ................ 3
2.2.1 Gramilometric Basis ........................................ 3
2.2.2 Equilibrium Beach Profile Methodology ........................ 9
3 METHODOLOGY AND RESULTS ...................................... 15
3.1 Native Beach Sediment Characterization ............................ 15
3.2 Equilibrium Dry Beach Width for Sediments Based on a Single Grain
Size ............................................................ 19
3.2.1 Selection of Two Representative Sediment Sizes ................ 21
Nourishment Sediment Finer than the Native .................... 21
Nourishment Sediments Coarser than the Native ................. 23
3.2.2 Effect on Additional Dry Beach Width ........................ 27
3.2.3 Effect of Sorting on Additional Plan Area Evolution ............. 33
4 SUMMARY AND CONCLUSIONS ...................................... 40
4.1 Sum m ary ....................................................... 40
4.2 Conclusions ..................................................... 40
5 REFERENCES ........................................................ 40




LIST OF FIGURES

FIGURE PAGE
1 Cumulative Distribution of Nourishment Sediment Sample from Perdido Key, FL.
Size in Millimeters ................................................... 2
2 Cumulative Distribution of Nourishment Sediment Sample from Perdido Key, FL.
Size in Phi Units Plotted on Normal Probability Paper......................... 4
3 Overfill Factor, K, Based on Method Developed by Dean (1974)..................5
4 Overfill Factor, RA, Based on Method Developed by James (1974). This Is the
Method Recommended in the Shore Protection Manual (1984) ...................6
5 Renourishment Factor, Rj, Based on Method Developed by James (1974). This Is the
Method Recommended in the Shore Protection Manual (1984) ...................7
6 Lognormal Distribution Approximations to Native and Borrow Sands in Virginia
Beach, Virginia Nourishment Project. Distributions From Example in Krumbein and
James (1965) ....................................................... 8
7 Sand Transport Losses and Beach Profiles Associated with a Beach Nourishment
Project........................................................... 10
8 Variation of Sediment Scale Parameter, A, with Sediment Size and Fall Velocity.
Note: A Values Presented in in"1. To Convert to ft"', Multiply by 1.486 (Dean,
1987)............................................................. 11
9 Measured (Solid Line) and Calculated (Dashed Line) Profiles at the U.S. Army Corps
of Engineers Field Research Facility, Duck, NC. The Calculated Profile Is Based on the Mean Grain Sizes and Eq. (5). Measured Profile and Sediment Sizes From
Stauble, 1992 ...................................................... 13
10 Three Generic Types of Nourished Profiles (Dean, 1991)...................... 14
11 Variation of Non-Dimensional Shoreline Advancement, AyIW., with A' and V.
Results Shown for B' (=B/h.) = 0.5 (Dean, 199 1)............................ 16
12 Variation of Non-Dimensional Shoreline Advancement, AyIW., with A' and V.
Results Shown for B' (=B/h.) = 0.25 (Dean, 199 1)........................... 17




13 Average Cross-Shore Distribution of Sediment Sizes for 165 Profiles Along Florida's
East Coast (Panel a). Comparison of Measured and Calculated (Eq. 5) Average of 165 Beach Profiles Along Florida's East Coast (Panel b). The Divergence for Depths Greater Than Approximately 4 m Is Believed to Be Due to this Being the
Approximate Closure Depth (Dean and Charles, 1994) ......................... 18
14 Example Illustrating Additional Dry Beach Width Variation with Three Single
Nourishment Sediment Sizes and Varying Nourishment Density, h. = 20 ft, B = 5 ft,
DN= 0.2 mm, DF1 = 0.275 mm, D2 = 0.2 mm, DF3 = 0.14 mm ................ 20
15 Example of Nourishment with Two Sediment Sizes, V1 = V2 = 160 yd3/ft, DN = 0.20
mm, DFl = 0.50 mm, D. = 0.20 mm ........................................ 22
16 Illustration of Method for Determining Portion of Nourishment Sediments with Mean
Size Equal to the Native for Nourishment Sediments Finer than the Native. DN = 0.2
mm, DF =0.14 mm, (1N = 0.0, OF =0.5 ....................................... 24
17 Fraction of Coarser Portion, Fl, and Mean Diameter of Finer Portion D2, as a
Function of Sorting of Nourishment Sediments ............................... 25
18 Volume of Shoreline Displacement, Ay as a Function of Sorting of Nourishment
Sediments for V-oT = 100 yd3/ft ............................................ 26
19 Illustration of Method for Determining Portion of Nourishment Sediments with Mean
Size Equal to the Native for Nourishment Sediments Coarser than the Native. DN =
0.2 mm, DF =0.275mm, ON = 0., F =0.5 .................................... 28
20 Fraction F,, and Mean Diameter, DFl, of Coarser Portion as a Function of Sorting of
Nourishment Sediments .................................................. 29
21 Volume of Shoreline Displacement, Ay as a Function of Sorting of Nourishment
Sediments for VTOT = 100 yd3/ft ............................................ 30
22 Variation of Shoreline Displacement with Volume Density and Proportions of
Coarser Fractions of Nourishment Sediments ................................. 31
23 Variation of Shoreline Displacement with Volume Density and Nourishment Sorting
Characteristics ......................................................... 32
24 Variation with Time of Equilibrium Dry Beach Plan Area Inside and Outside of
Nourished Segment and Total Plan Area. Beach Nourishment Conditions Given in
Table 4. DN = 0.2 mm,DF = 0.14 mm, UF= 0.2 ................................ 34
25 Variation with Time of Equilibrium Dry Beach Plan Area Inside and Outside of
Nourished Segment and Total Plan Area. Beach Nourishment Conditions Given in
Table 4. DN= 0.2 mm,DF = 0.14 mm, OF= 0.5 ................................ 35




26 Variation with Time of Equilibrium Dry Beach Plan Area Inside and Outside of
Nourished Segment and Total Plan Area for Nourishment Sediment Same as Native.
Beach Nourishment Conditions Given in Table 4............................ 36
27 Variation with Time of Equilibrium Dry Beach Plan Area Inside and Outside of
Nourished Segment and Total Plan Area. Beach Nourishment Conditions Given in
Table 4. DN=O0.20 mm, D F = 0.275 MM, OF=O0.2............................ 37
28 Variation with Time of Equilibrium Dry Beach Plan Area Inside and Outside of
Nourished Segment and Total Plan Area. Beach Nourishment Conditions Given in
Table 4. DN= 0.20 mm,D D= 0.275 mm, a. = 0.5............................ 38




LIST OF TABLES
TABLE PAGE
1 Correspondence Between Sediment Sizes in mmn and 4 Units ....................3
2 Summary of Overfill Factors Based on Three Methods for the Sediment Distribution
Presented in Figure 6: PF = 2.96, PN = 1.5, OF = 1.76, ON = 0.91 ...................7
3 Summary of Recommended A Values (0t3) for Diameters from 0. 10 to 1.09 mmn..... 12
4 Characteristics of Beach Nourishment Project Considered ...................... 33
5 Summary of Total Plan Area for Various Cases Considered, DN = 0.2 mm, ON = 0 .... 39




BEACH NOURISHMENT DESIGN:
CONSIDERATION OF SEDIMENT CHARACTERISTICS
1 INTRODUCTION
In beach nourishment projects, the nourishment sediments usually differ in size characteristics from those of the natural sediments distributed across the active beach profile. Thus, the project engineer must account for these differences in developing predictions of the performance of the beach nourishment project. The differences in sediment characteristics can be manifested in both the longshore performance of the project due to spreading out of the beach nourishment planform and also in the cross-shore dimension which is a result of the different equilibrium beach profile characteristics for the two sediments. This report focusses on the latter issue. For nourishment sediments with different size characteristics than those on the active profile, what is the most appropriate methodology available to the design engineer to account for these differences?
Two separate concerns are addressed in this report. The first is methodology for characterization of the sediments present in the pre-nourished profile. These results serve as a basis for comparison with the candidate nourishment sediments. The second issue to be addressed is the development, and illustration by example, of the methodology for predicting the equilibrated nourished profile composed of sediments that are different than the native.
2 BACKGROUND
2.1 The Phi Scale for Sediment Size Characterization
The size characteristics of sediments can be represented in several ways. The most intuitive and direct approach is one in which the geometric size characteristics are reported; for example, in millimeters. Figure 1 presents a cumulative distribution of sediment sizes expressed in millimeters from a nourished profile on Perdido Key in the Panhandle area of Florida. A second approach, first proposed by Krumbein (1936), is through the so-called phi (4 ) scale
4= log2(D(MM)) (1)
Given the 4 size, the geometric size, D, is recovered as
D(mm) = 2-' (2)
The phi scale has been used primarily by geologists and has a number of advantages and disadvantages. The most obvious disadvantage is that the scale is inverse such that larger diameters are represented by smaller and possibly negative values of phi and vice versa for smaller sediment sizes. Table 1 presents a listing of several sediment diameters and their associated phi values. One advantage of the phi scale is that the size distribution of most sediments can be approximated by a




1.0 0.9 0.8 a 0.7

'0.6
0
o 0.4
0.
.. 0.3
0.2 0.1
0.0.-

9 8 7

6 5

Sediment Size, D (mm)
Figure 1. Cumulative Distribution of Nourishment Sediment Sample from Perdido Key, FL. Size in Millimeters.

. . . . . . . . . . . . . . . . . . . . . . . . .
. ...............
- - - - - -




Table 1
Correspondence Between Sediment Sizes in mm and 4) Units Sediment Sizes
4) Units D(mm)
-3 8
-2 4
-1 2
0 1
1 0.5
2 0.25
3 0.125
4 0.0625

normal probability form when the presented as

sediment size is expressed in phi units. This distribution is

(, )2
1 20e27

where a is the standard deviation of the distribution (also called the "sorting") and p is the mean of the distribution, also in 4) units. For well-sorted sediments, a 0.5 and for poorly-sorted sediments a> 1.0. Sediments which are "well-sorted" and "poorly-sorted" are also referred to as "poorlygraded" and well-graded", respectively. When plotted on normal probability paper, the cumulative distribution of the sediments expressed in phi scale is linear if Eq. (2) provides a good representation of the size distribution. Figure 2 presents the cumulative distribution for the same sample as in Figure 1 where it is seen that the size distribution is reasonably linear on the normal probability distribution paper. In the development which follows, we will extensively employ the phi (4)) representation for sediment size characteristics.
2.2 Earlier Methodologies of Accounting for Sediment Sizes
Earlier methodologies, which have accounted for the differences between native and nourishment sediment sizes for purposes of beach nourishment design, have been based both on granulometric (grain size) comparisons and equilibrium beach profiles methodologies. Each of these is reviewed below.
2.2.1 Granulometric Basis
The earliest approach to establishing a comparative basis for accounting for differences between nourishment and native sediments was proposed by Krumbein and James (1965). This




99.999% 99.99% 99.9%
99%
-c90% Q) 70% i~50% C30% ~,10%
1%
0.1%
0.01% 0.001%

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
....................................................................... ......................
Approximate Best Fit Line
.......................................................... ...........................
...................... ..................... ...........................
.................. .................... .......... ...............
................ .. . .. ....................
................................. ............................. ................. ........
............. .................................. ............................. ........................... .
............ ................................... ............................. ...........................

V Coarser I ZaFiner ON
40 Grain Size in 4 Units
Figure 2. Cumulative Distribution of Nourishment Sediment Sample from Perdido Key, FL. Size in Phi Units Plotted on Normal Probability Paper.




methodology assumed that both the native and nourishment sediments were log-normally distributed as represented by Eq. (3) and considered that the nourishment sediments would be modified such that their modified distribution in phi units would represent an exact match to the native. This method discounted portions of the nourishment sediment distribution which were both finer and coarser than the native, thus resulting in an effective "loss" of these portions of the nourishment sediment distribution. The results were expressed in terms of an "overfill" factor representing the number of units of nourishment sediments that must be provided to result in one equivalent unit of native sediments. While it appeared reasonable to discount the finer portion of the nourishment sediments, it did not appear reasonable to discount the coarser portion.
Dean (1974) modified the Krumbein-James method by again considering a distribution represented by Eq. (3). This method discounted only the finer portions of the nourishment sediments with the requirement that the remaining portion of the distribution have the same mean sediment size as the native. This, of course, resulted in a smaller overfill factor (predicted better performance) such that less nourishment sediments were required to result in one equivalent unit of native sediments. The overfill factor from this method is presented in Figure 3. The overfill factor, K, is a function of the non-dimensional mean of the fill, iP/oF, and non-dimensional mean of the native, JpN/oP Here subscripts "F" and "N" denote "fill" and "native", respectively.
301 60 .
2.0 15.0 f,O"p ,,/
Fiur,. OeflFatrKBsd on Method Deelpe bDa (1974).,
/, / NX e:
0. V. 0.60. 1.0 2 .
Figure.0 3. Ovrfl Fatraae nMehd Deopaed thea
(1974)Unit




James (1974), recognizing the lack of realism in the overfill factor by Krumbein and James (1965) also developed an approach which resulted in both a new definition of the overfill factor and a so-called "renourishment factor". This method considered the placement of a beach nourishment project in an area subject to erosive processes and the presence of a winnowing process by which the finer portion of the nourishment sediments would be winnowed out until the size distribution was the same as the native. This methodology is recommended in the U.S. Army Corps of Engineers Shore Protection Manual (1984) and is shown as Figures 4 and 5. The results presented in Figures 4 and 5 depend on the non-dimensional mean differences and sorting ratios as shown on the axes.
5.0 4.0o o ,
W '. F -" "'
3.0
2.0 values of RA
0.8
Quadrant 2 :- :Qarn
1.2 . . . .-.-.-.
.... ........
0.6 ...
0.5
O.3
O -4 -3-2 -I0 1 2 3 4
O~FN
Figure 4. Overfill Factor, RA, Based on Method Developed by James (1974). This Is
the Method Recommended in the Shore Protection Manual (1984).
An example will serve to illustrate the results from the various methods. Figure 6 presents nourishment and native distributions presented in Kreimbein-James (1965) report for which the overfill factor is 3.09 as presented in Table 2. For the same size distribution, the overfill factor determined by the Shore Protection Manual method is 2.95 and using the methodology proposed by Dean is 2.05. The renourishment factor for this particular size distribution is 1.4 and represents the frequency of renourishment using the borrow sediments relative to the frequency of renourishment if there were an exact match between the borrow and native sediments.




ues of Rj
3.0 _bl
2.5 1

0.21
-4

0

~~~~1

+ ~:

1.0 0 1.0 2.0 3.0 4.0
RF-AN

Figure 5. Renourishment Factor, R,, Based on Method Developed by James (1974). This Is the Method Recommended in the Shore Protection Manual (1984).

Table 2
Summary of Overfill Factors Based on
Three Methods for the Sediment Distribution
Presented in Figure 6: 'F = 2.96, PN = 1.5, OF = 1.76, ON = 0.91 Method of Overfill Factor
Krumbein-James (1965) 3.09
Dean (1974) 2.05
James (1974) 2.95
(also Shore Protection Manual (1984))

.w

#*;::rl

st" "n-a

....u ... ...

-A.




Grain
4 2 i 0.5
i i i I I

Size (am)
0.2

0.1 0.05

0.02 0.01
I I

Grain Size, 4

Fine

Figure 6. Lognormal Distribution Approximations to Native and Borrow Sands in Virginia Beach, Virginia Nourishment Project. Distributions From Example in Krumbein and James (1965).




The granulometric basis for characterizing sediments has no direct linkage with the performance characteristics of the sediments in terms of either the cross-shore dimension or the longshore ("spreading out") characteristics, both of which are relevant to beach nourishment project performance, see Figure 7.
2.2.2 Equilibrium Beach Profile Methodology
In contrast to the granulometric approach, the equilibrium beach profile methodology is process based and provides a direct link between the sediment characteristics and the performance characteristics of interest, particularly the additional dry beach width yielded as a function of the volume density of sediment added (Figure 7). The equilibrium beach profile (EBP) methodology is based on the following simple representation for equilibrium beach profiles
h(y) = A(D)y2'3 (4)
in which h represents the water depth at a distance, y, from the mean water line and A(D) is a socalled sediment scale parameter which depends on the median sediment size, D. This form was first proposed by Bruun (1954) and later confirmed by Dean (1977) using in excess of 500 beach profiles extending from the eastern end of Long Island south around the Florida Peninsula and extending westward to the Texas-Mexico border. The sediment scale parameter, A(D), has been shown by Moore (1982) and Dean (1987) to vary with sediment size as shown in Figure 8. A number of tests of the equilibrium beach profile methodology have been developed (Dean and Charles, 1994; Dean et al, 1993). Table 3 presents values of the sediment scale parameter, A(D), for sand sized sediment at 0.01 mm increments.
Equation (4) applies for the case in which a single sediment size is present across the entire profile; however, it is well-known that there is usually a sorting of sediment sizes with the coarser sediments residing in the shoreward portions of the profile and the finer sedimetits present in the outer portions of the profile. EBP concepts can be applied for the case of non-uniform sediments across the profile by the following equation
-- 23/2 W
h(y) =h 32(yj) +Ai (y-Yj)J ,yJ where the sediment scale parameter, A, is now piecewise uniform across the profile and A, is the value of the sediment scale parameter between yj and yj+l. Equation (4) provides the flexibility to apply equilibrium beach profile concepts to situations in which the sediment size distribution across the profile is arbitrary.
Figure 9 presents a comparison of a profile from the U.S. Army Corps of Engineers Field Research Facility in Duck, NC with the results of applying Eq. (5). The sediment size distributions which are presented above the profile are probably the best well-documented in the world. It is seen that there is quite good agreement between the native and predicted profiles; however, the degree of agreement is considered somewhat fortuitous.




Original Shoreline

"Spreading Out" Losses

Sand Moves Offshore to Equilibrate Profile
Nourished Shoreline "Spreading Out" Losses a) Plan View Showing "Spreading Out" Losses
and Sand Moving Offshore to Equilibrate Profile

Dry Beach Width (Coarse Sand)
Initial Placed Profile
Equilibrated Profile (Coarse Sand)

Dry Beach %N (Fine Sand)

Original Profile

Equilibrated Profile (Fine Sand)

b) Elevation View Showing Original Profile, Initial Placed Profile
and Adjusted Profiles That Would Result by Nourishment
with Coarse and Fine Sands
Figure 7. Sand Transport Losses and Beach Profiles Associated with a Beach Nourishment Project.




SEDIMENT FALL VELOCITY, w (cm/s)
0.01 0.1 1.0 10.0 100.0
1.0SugseEmiia O
Relationship A vs. D W(Mre) ,
Irom Hughes!
From Idividual Field F ResultsA= 0.067 w
Profiles where a Range
of Sand Sizes was Givn
0.10
ZFrom Swart's
Laboratory Results
0.01
0.01 0.1 1.0 10.0 100.0
SEDIMENT SIZE, D (mm)
Figure 8. Variation of Sediment Scale Parameter, A, with Sediment Size and Fall Velocity. Note: A Values Presented in m"3. To Convert to ft"3, Multiply by 1.486 (Dean, 1987).




0.00 F 0701 0.02 0.03 0.04 0.05 0.06 0.07 0.08
0.1 0.0936 0.0999 0.1061 0.1123 0.1186 0.1248 0.1296 0.1343 0.1391 0.1438
0.2 0.1486 0.1531 0.1575 0.1620 0.1664 0.1709 0.1739 0.1768 0.1798 0.1828
0.3 0.1858 0.1887 0.1917 0.1947 0.1976 0.2006 0.2036 0.2066 0.2095 0.2125
0.4 0.2155 0.2178 0.2202 0.2226 0.2250 0.2274 0.2297 0.2321 0.2345 0.2369
0.5 0.2392 0.2410 0.2428 0.2446 0.2464 0.2482 0.2499 0.2517 0.2535 0.2553
0.6 0.2571 0.2589 0.2606 0.2624 0.2642 0.2660 0.2678 0.2696 0.2713 0.2731
0.7 0.2749 0.2762 0.2776 0.2789 0.2803. 0.2816 0.2829 0.2843 0.2856 0.2869
0.8 0.2883 0.2895 0.2907 0.2919 0.2930 0.2942 0.2954 0.2966 0.2978 0.2990
0.9 0.3002 0.3014 0.3025 0.3037 0.3049 0.3061 0.3073 0.3085 0.3097 0.3109
1o 0.3121 0.3144 0.3156 0.3168 0.3180 0.3192 0.3204 1 0.3216 1 0.32281

Table 3
Summary of Recommended A Values (ft") for Diameters from 0. 10 to 1.09 mm




-3l I o
2 4.0 E
- 2.0
w 0 -- --- 1.0 w
L k 0.5 "
2 0.25 Z
N -- 0:125
o 4 .63o
5 0.031
11 5
D A IROM DAR
Fne ath
fom nldn h floing th:diinldybahwdh y/ nwihA steadtoa
diryeac widt ofaste eqlibratne)ad rofluad (Dshewdt ofie) becProfile utt the Arylosre
dpon thine naie Rofierc Fiite.,DukN.ThCacltdPoieIBsdonheMn
P 3-2 (6)
Frtoecssin whichANi the sediisment sclaarmtrdo h native sediment Thann-densional horeinteb
dveeptn t cne pressled ase.
W,0 BW,'__ (7)




Added Sand

Added Sand -~ b) Non-intersecting Profile

-1

Nourished Profile

Added Sand--** c) Submerged Profile AF wAN Figure 10. Three Generic Types of Nourished Profiles (Dean, 199 1).




in which V is the nourishment volume density, i.e., the volume of the nourishment sediments per unit beach length, B is the berm height, AF is the sediment scale parameter for the nourished (or fill) sediments and h. is the so-called closure depth, i.e., the depth to which it is assumed the beach nourishment sediments will equilibrate if the profiles are non-intersecting. Figures 11 and 12 present the relationships in Eq. (7) for two values of B/h. = 0.5 and B/h. = 0.25, respectively.
3 METHODOLOGY AND RESULTS
Two issues are addressed in this section. The first is a characterization of the native beach sediments such that this composite can be compared on a rational basis with the sediment characteristics obtained from the borrow area. The second issue is the application of the nourishment sediments to the prediction of equilibrium dry beach width and the evolution of the dry beach plan area. The emphasis in this second issue is a rational incorporation of the effect of the nourishment sediments sorting values.
3.1 Native Beach Sediment Characterization
As noted previously, nature sorts sediments on the profile such that the coarser sediments are generally located near the shallower nearshore portions and the finer sediments reside in deeper waters. An explanation of this sorting is that the more energetic regions of the nearshore zone are in the shallower water due to the breaking waves and currents and the finer sediments tend to be winnowed out from this region and settle where they can remain dynamically stable with the hydrodynamic conditions that occur. Figure 13 presents results from Dean and Charles (1994) showing the average profile and cross-shore distribution of average sediment size for 165 profiles along the east coast of Florida.
Consider I samples each represented by Eq. (3) and each having a different mean, Pi', and standard deviation (sorting), a,. The question addressed is if we were to place these samples each of the same weight in a container and mix them completely, what would be the resulting composite mean and standard deviation? It can be shown that the mean and standard deviation of the composite sample, pc and a,, respectively are represented by Eqs. (8) and (9).
1'1
L P Ii' (8)
Eq. (9) can also be represented as
[ 1 2 1+ I( 2_11
ac IE i E i- E 11/2(10)




0 1.0 2.0 2.8
A'= AFIAN
Figure 11. Variation of Non-Dimensional Shoreline Advancement, Ay/W., with A' and V'. Results Shown for B' (=B/h.) = 0.5 (Dean, 1991).
16




1.0

0.1 '_-_- ,I,.
A VI ... -
S Asymptotes ",_ ___fay- ',u* I 0 0
W B I
i *.,, :*- 7 i '
ef1 t S ..L"' "
0.0001I
10 2.0 2.8
A' =A IAN
Figure 12. Variation of Non-Dimensional Shoreline Advancement, Ay/W., with A' and V'.
Results Shown for B (=B/h.) = 0.25 (Dean, 1991).
0.0001 .., ,,, -- "
Figre12. fiction Nn-e nsionalI Soein Adaceet AyW. wihAn
ReutsSon o (=/. 02 iDan 9 )




0 100 200 300 400 500
Offshore Distance (mn)

600 700

a) Measured Sediment Sizes, Dso%, (MM)
Averages for 165 Florida East Coast Profiles
... ... ..... ... ... ... .. ... ... ... ..
. .. .. .. . . .. . .. . ... . . .
...........................
. . . . . . . .
... ... .. ... . . . . .. . .% . .
..... a Measured .......................- ....
~ Calculated
...................

0 100

200 300 400 500
Offshore Distance (Wn

600 700

b) Comparison of Measured and Predicted Profiles
Averages for 165 Florida East Coast Profiles
Figure 13. Average Cross-Shore Distribution of Sediment Sizes for 165 Profiles Along Florida's East Coast (Panel a). Comparison of Measured and Calculated (Eq. 5) Average of 165 Beach Profiles Along Florida's East Coast (Panel b). The Divergence for Depths Greater Than Approximately 4 mn Is Believed to Be Due to this Being the Approximate Closure Depth (Dean and Charles, 1994).

0.7 0.6 0.5
0.4 0.3
0.2 0.1 0.0

...........
.... ... ................ ... ........... ....................
..... ..... .......... ......................
. ......... ......................
: .......... D50%, (mm)j
............ ......................
........... ........... .......... .........
....................
.......... ........... ........................
.......... ...........
.......... ........... ........... ..................... (79)......... ....... ...... (1,66 .......... (147) .......... (fig) ....
. ........ ............... .......... ... .....
..................................: ........... ........... .......... ..........
. ......... ..................... ........... ..................... ......
........... ...................... ..........................

0
-5
-10




App lication of these equations allows determination of the composite mean and sorting associated with the active portion of the native beach profile.
Usually the sediment samples taken across a native profile are not uniformly sampled with respect to offshore distance. It is more likely that the sampling is uniform with respect to depth. The methodology introduced in the previous paragraphs provides a basis for employing sediment samples which are not uniformly distributed with respect to offshore distance to establish the composite mean and standard deviation of the native profile. The approach is to apply weighting factors which represent the cross-shore distance represented by each sediment sample. Defining these weighting factors as wi, the counterparts to Eqs. (8) and (9) are
PIC =i=1I (11)
~3w.
i=1
3.2 Equilibrium Dry Beach Width for Sediments Based on a Single Grain Size
Non-dimensional values of equilibrated dry beach widths for nourishment sediments based on a single grain size have been developed and are presented in Figures I11 and 12. An interesting feature of nourishment sediments composed of single sized sediments is that in which the nourishment sediment is finer than the native. Figure 10c has shown that for this case, submerged profiles can occur. Figure 14 shows a comparison of the shoreline displacement for three nourishment sediment sizes each represented by a single value versus the volume density of material added in the nourishment. In Figure 14, the native sediment size is 0.2 mm and the three nourishment sediment sizes are 0.275 mm, 0.20 mm and 0. 14 mm. It is seen that for the sediments coarser than the native (0.275 mm) the additional dry beach width increases rapidly with volume added and then becomes approximately parallel to the case in which the nourishment sediment has the same size as the native (0.2 mm). The third case is that of a sediment size equal to 0. 14 mm and it is seen that a threshold volume density of approximately 235 yd3/ft exists prior to the appearance of any emergent beach. The results shown in Figure 14 are equivalent to a zero sorting value in Eq. (3). The sorting values for nourishment sediments will usually range between approximately 0.5 and 1.5. Thus, the results shown in Figure 14 for a nourishment sediment size smaller than the native and with realistic sorting will not be so extreme since a portion of the nourishment sediment will have grain sizes equal to and greater than that of the native profile.




500
DN=Q0.2 mm
E
(D
Q
00
0 100 200 300
Volume Density (yd3/ft)
Figure 14. Example Illustrating Additional Dry Beach Width Variation with Three Single Nourishment Sediment Sizes and Varying Nourishment Density, h. = 20 ft, B = 5 ft, DN = 0.2 mm, DFI = 0.275 mm, D. = 0.2 mm, DF3 = 0. 14 mm.




The following sections describe methods for establishing two grain sizes to represent the nourishment sediment and the application of these grain sizes to prediction of the equilibrium beach profile.
3.2.1 Selection of Two Representative Sediment Sizes
For purposes here, we consider the native profile to be represented by a single grain size and the nourished profile to be represented by two grain sizes, one of which is equal to the native sediment size. Additionally, it will be assumed that the coarser of the two representative nourishment grain sizes is located landward of the other sediment. Figure 15 illustrates these considerations. Requiring that one of these sediments be of the same size as the native results in only one type of equilibrium beach profile in contrast to the three types shown in Figure 10; that is, there will only be non-intersecting profiles as shown in Figure 10b.
Given a particular nourishment sediment which has the distribution represented by Eq. (3), the question arises as to the partitioning of this grain size distribution such that a portion has the same mean size as the native. This problem will be considered as two separate cases: nourishment sediment finer than the native and coarser than the native. In the following development, the inshore and offshore nourishment volume components will be assigned the subscripts 1 and 2 as shown in Figure 15.
Nourishment Sediment Finer than the Native. For this case the portion of the nourishment sediment which has the same grain size as the native will be the coarser fraction and thus will reside in the inshore portion of nourished profile. The equation defining the mean of this portion is
PF P = P I +erf(13)
where 4 represents the value of 4 which divides the two portions of the nourishment sediment and must be determined by iteration. The mean sediment size of the other fraction of the nourishment sediment, that is, that finer fraction that is considered to reside offshore is given by
OF e (kPiF)2/24
PF,: PF + (14)
The fraction of material which has the same grain size as the native is




10
0
0
-. -10
U)
1",J
-20
-30
-1000

0 1000 2000
Distance From Original Shoreline (ft)

Figure 15. Example of Nourishment with Two Sediment Sizes, V, = V2 = 160 yd3/ft, DN = 0.20 mm, DFI = 0.50 mm, DF = 0.20 mm.

3000




F = II +erft (15)
To illustrate by example, consider the case in which the native sediment size and sorting are 0.2 mm and 0, respectively, and the mean diameter and sorting of the nourishment sediment are 0.14 mm and 0.5. Figure 16 presents the two grain size distributions. The value of 4 for this case is 2.66( the mean of the fraction considered to reside offshore, p 2 = 3.1334 (= 0.114 mm) and the fraction, F,, of the same size as the native and is hatched in Figure 15, and is F, = 0.363.
For this case, the effect of sorting of the nourishment sediment on proportion, F,, of the same mean size as the native and the mean size of the offshore portion are presented in Figure 17. It is seen that with increasing sorting, the fraction of material having the same mean grain size as the native increases; thus for this sediment, one would anticipate the additional equilibrium dry beach width to increase with sorting of the nourishment sediment. Additionally, the mean diameter of the offshore portion decreases with sorting. Figure 18 presents the additional dry beach width variation with sorting values of the nourishment sedimen for a nourishment density of 100 yd3/ft.
Nourishment Sediments Coarser than the Native. For the nourishment sediment coarser than the native, the procedure parallels that of the previous case. The requirement that the finer portion of the nourishment grain size distribution have the same mean as the native is expressed as
OF e -P)22
JPN PF f + (16)
where erf is the so-called "error function" and (. represents the value of 4 which separates the nourishment grain size distribution into the portion having the same mean size as that of the native sediment and the other coarser portion. Again, it is necessary to obtain the value of i by iteration. For this case, the mean grain size of the coarser fraction, pFI' is given by
OF e-(*'-pF)2o
PF1 11F I+ef(17)
and the fractions of the nourishment material which has the mean grain size of the native is denoted F2 and is given by




2.0 I i
1.8
.6 .. . . . ..................... .... .. . . . .. . . . .. . . . .
1.6 . . . . .
1Native: Sediment..
1 .4 ......... ........ .... ...... ........ . . . . .. . . . . ., . . . . ..
=2.32i: u vr"
1= erage.o.Nourishment
1 .2 ......... .. ........ ............ ....... ... .... .. ... .. . . .. . .
. Sediment =2.74
. .. .. ... .. .. . ....... .. : ................ ....................
4- E
0 8 . . . . . .. . . . . . . . . " . . . . . . . . . .
Cr) ,
0.6 ...................................... ...
o .. .......................................... ...........................
0.2~~o .............
0.0
0 1 2 3 4 5
Coarse Fine
Figure 16. Illustration of Method for Determining Portion of Nourishment Sediments with Mean Size Equal to the Native for Nourishment Sediments Finer than the Native. DN = 0.2 mm, DF = 0.14 mm, oN = 0.0, uF= 0.5




1.0 I
o~g ... ... ...D ki.0 ...rm........... .... .. .. .. .................
0 .9 -- - ------- --------
0.5 ......................
0.4
0 .1 . ,2 .. .. .. .. .. .. :. . . .............. .................. ......
0 .0 . . . . . . .. ..
0 1 2 3 4
Sorting of Nourishment Sediments, aF
Figure 17. Fraction of Coarser Portion, Fl, and Mean Diameter of Finer Portion Dm, as a Function of Sorting of Nourishment Sediments.




100
90 ........... DN=2-0:20mm .................... ------------------------------ ------80 ...........D F = O 14 :m m ...... ............. !...........................! ..........................
80 F
* ecis
* 400
Cr
10
0 1 2 3 4
Sorting of Nourishment Sediments, aF
Figure 18. Volume of Shoreline Displacement, Ay as a Function of Sorting of Nourishment Sediments for VTOT = 100 yd3/ft.




F 2 :_ 1 1 erf (18)
2 VF2 (7F I
An example will illustrate the case for a nourishment sediment size greater than the native. Considering a mean nourishment sediment size of 0.275 mm, a sorting of 0.5 and a native sediment with a mean size of 0.2 nun and a sorting of 0.0, the portion of the nourishment sediment with a mean grain size equal to the native is shown in Figure 19 and is hatched. For this example, was found by iteration ( = 1.995), the mean size of the inshore sediments is p,,, = 1.52 4) (DFI = 0.349 mm) and the fraction of sediments having the same mean size as the native is F2 = 0.427.
As would be expected, the effect of increasing sorting is to cause an increase in the fraction of the sediment which has the same mean grain size as the native. Figure 20 presents the variation in the inshore fraction of sediment and mean diameter with sorting. The equilibrium dry beach width variation with sorting of the nourishment sediment is shown in Figure 21 for a nourishment density of 100 yd/ft and is contrary to that shown in Figure 18 which applied for the cause of nourishment sediments coarser than the native. In the present example, an increase in the sorting values increases the finer portion of the sediment distribution more than the coarser portion and thus the additional equilibrium dry beach width decreases with sorting values of the nourishment sediment. At some value of sorting, the portion of the coarser sediment is so small that it all resides in the non-active additional dry beach width portion of the beach (within the berm width) and for larger values of sorting, the additional dry beach width is identical to that for a single sized sediment of the same size as the native.
3.2.2 Effect on Additional Dry Beach Width
The effects of representing the nourishment profile size characteristics with two sediment sizes will be illustrated in several ways. The first will be to simply consider the nourishment sediments to be composed of various fractions of the coarser and finer sediments. Figure 22 presents, in the same format as Figure 14, the shoreline displacement versus volume densities for nourishment sediments with mean sizes coarser than, equal to and finer than the native. This plot presents as bold lines the three cases presented earlier in Figure 14. For the nourishment sediment sizes that are coarser than the native, two additional lines are presented. One of these lines is for the coarser sediment containing 80% of the fraction of the nourishment sediment and one containing 50% of the nourishment sediment. It is seen, as would be expected, that the greater the fraction of coarser sediment the larger the shoreline displacement for a given volume density. For nourishment sediment with mean diameters finer than the native, the opposite is the case. For nourishment and native sediment sizes equal to 0.14 mm and 0.2 mm, the greater the proportion of 0.2 mm, the larger the shoreline displacement for any given volume density. The results illustrated for this case will next be examined in terms of the sorting characteristics of the nourished sediments.
Figure 23 presents the results in the same format as in Figure 22 except now the portions of the nourished sediments of the same size as the native and the complementary fraction are determined based on the sorting considerations discussed earlier. It is seen that for a mean nourishment sediment size of 0.275 mm with a sorting of 0.5 and a native sediment size of 0.2 mm, the shoreline displacement is approximately mid-way between the cases for zero sorting of the




2.0
1 .8 ... ...... ...... ... ." ......................... !.....................................................
1 .8 -- - ---
1 .6 ... ... ... .. ... ... ... ... .. ... ... ... .. ........ ................. ..........................
1.6 .. . . . .. . . . .
1 4 . . . . . . . . . . . . . . . . . . . . . . ..-- - . . .- . . . . . . . . . . . . . . . . . . . . . .
1.4
1.2 -Average-of Nourishment ................. E ...........................................
Sediment = 1.85 (p (
.. . . . . . . . . . ..i... .. . . . . - -. .t- .i . ..-.
9 1 0 . . . . . . . ... . . . . . . .. . .
oi.o .CI.) .V/
0.8*- .. .Native Sedi ment
0.6 ............................ ..
0.4 ....4...4#
0.2 2.32 4
..... .... .._... ... ... ... .. _... ... ... ... ... ...
0 6. ........ -- -- '* .. .....I I
0 1 2 4
Coarse Fine
Figure 19. Illustration of Method for Determining Portion of Nourishment Sediments with Mean Size Equal to the Native for Nourishment Sediments Coarser than the Native. DN = 0.2 mm, DF = 0.275 mm, GN = 0.0, F = 0.5.




1.0
.~ . . .. ..' . . .. .. .. .. .. .. .. .. .............. .: 6 .52 m . .. ... .. .. .. .. .. .. .. .. .. .. .. ..
0.9 ......-\ ................ .. .: ... ... ... .. : . F : 5 ri i . . . . . . .
D = 0.20 mm
0.8 U --- ---------- m m-0.8D = 0.275 mm
0.7 ....... ..
0.6
0.5
0.4 ........0.3 -- -0 .2 .... .... .... ...
0.0 I
0 1 2 3 4
Sorting of Nourishment Sediments, aF
Figure 20. Fraction Fl, and Mean Diameter, DFI, of Coarser Portion as a Function of Sorting of Nourishment Sediments.




240
>,200 ..... .........................D.O~m..........
DF=Q0.275 mm
o 160 ................................................... -------------------Cd)
S 120.................................................... .........................
00
0 12 3 4
Sorting of Nourishment Sediments, aF
Figure 21. Volume of Shoreline Displacement, Ay as a Function of Sorting of Nourishment Sediments for VT = 100 yd3lft.




500

_." I "" II"
4! 0 0 ............................................... . . .. . . ........... . ..... .......
a)
01
C
a ) 2 0 0 - - - - - --.. . . . ..0 . . . . ... . . - . - - 3 - .
100.. .. .". .......... .." ....'...
10 .............--" '" ". "
.22
0 ... ...--------0 100 200 300
Volume Density (yd3/ft)
Figure 22. Variation of Shoreline Displacement with Volume Density and Proportions of Coarser Fractions of Nourishment Sediments.




500
DN = 0.2 mm
S 4 ..................................................... ... .......
300 ...............................
0
........ ...............
" c 1:20000
CL
0
c oo 100. ......... ............ .......-.- ....... .....
(D 2 0 . ... ... ........... ... ""00 .. - ..
0
0 100 200 300
Volume Density (yd3/ft)

Figure 23. Variation of Shoreline Displacement with Volume Density and Nourishment Sorting Characteristics.




Project Ungth 2 mi
Depth of Closure, h. 20 ft
Berm Height 5 ft
Nourishment Density 100 yd3/ft
Native Sand Size 0.2 mm
Native Sand Sorting 0
Nourishment Sand Characteristics Variable Evolution Time Considered 0 20 years
Background Erosion Rate 0

nourishment sediments and for the case where all of the sediment is composed of 0.2 mm. For the case in which the mean sediment size is 0. 14 mm, and for the case of a sorting value of the nourishment sediments equal to 0.5, the additional dry beach width again lies between the case of
0.2 mm with zero sorting and 0. 14 mm. with zero sorting.
3.2.3 Effect of Sorting on Additional Plan Area Evolution
The scenario considered here is for the case of an initially rectangular beach nourishment platform on an otherwise long, straight beach. An interesting consequence which arises due to using sediment coarser than or finer than the native is that the sum of the plan areas inside and outside of the nourishment segment can be shown to change with time as can be seen by referring to Figure 14. For sediments coarser than the native, the ratio of additional dry beach width to volume density is seen to be greater per unit volume for smaller volume densities. However, for the case of nourishment sediment finer than, the native, the additional dry beach width per unit volume added decreases as the nourishment density decreases. The consequence is that with evolution of the beach nourishment project, the sediment spreads out resulting in smaller and smaller volume densities. Thus, for projects constructed with nourishment sediment sizes coarser than the native the total additional plan area will increase with time whereas for those constructed with nourishment sediments finer than the native the total additional plan area will decrease with time. This effect will be shown for a project which is somewhat typical for the Florida east coast. The characteristics of this project are presented in Table 4 and the results are presented in Figures 24 through 28, and are discussed below.
Table 4
Characteristics of Beach Nourishment Project Considered

Figure 24 presents the variation with time of the plan area within the nourished segment, outside the nourished segment and the total plan area for the project conditions in Table 4 and for a nourishment sediment characterized by a mean diameter, DF = 0. 14 mm and a sorting, oF = 0.2. Of course, the plan area within the nourished segment decreases with time and that outside the nourished segment increases with time. However, the total plan area (sum of inside and outside the nourished segment) decreases with time as discussed earlier and in accordance with Figures 14 and




S .. . . ................... . .
.... ofia

co)
W
C
-
C
0
V

0.6 0.5
0.4 0.3
0.2 0.1 0.0

loe

S... .
.
. .. %

S O- .-....Out ,lde- o ---:-- : DN = 0.20 mni
-- : = 014.mn
.- ...................... .. ......... .......... .......... F .
F = 0.2
, i l I 1 I I

20

Time (years)
Figure 24. Variation with Time of Equilibrium Dry Beach Plan Area Inside and Outside of Nourished Segment and Total Plan Area. Beach Nourishment Conditions Given in Table 4. DN = 0.2 mm, DF = 0.14 mm, oF= 0.2.

8

. . . . . . .

.... ..........q.......... ............o..........
.... ......... .................................

...........




..... To< : 1 0 .......... i........... .......... .......... .......... ......... "........... .......... !..........
< 10 DN =.20mm
"D ,F = 0.14 mim
8F
: : :-. j .,b'r,,.,,: :: a,= 0-5:
6 .......... '"-". ..... .
6 ......: .......:.. . . .. ..
a) d . ..L. ...
0
2 ........... -0 .................. .................................. ........ ...
O0 / I r I I I i I ,
0 2 4 6 8 10 12 14 16 18 20
Time (years)
Figure 25. Variation with Time of Equilibrium Dry Beach Plan Area Inside and Outside of Nourished Segment and Total Plan Area. Beach Nourishment Conditions Given in Table 4. DN = 0.2 mm, DF = 0.14 mm, a. = 0.5.




CU)
U
(1)
C (0
V
V=

. .
. . . .

10

/
/

Total
* i-S.....
"- //
: . :: -.. ... - - -_-- - - - - - -.7- - -, .-- - - -
... ... W ... ....... .. ... .. ,..- .-.. -.... ...... ......... .. ... ..........
, l~e Orisl .......no rr
Uts ... .. ..... .. ..." I ---- :' ,2 0- .... II ....
DF 0.20 mm
- IFI =:0.0
, I I I ,

20

Time (years)
Figure 26. Variation with Time of Equilibrium Dry Beach Plan Area Inside and Outside of Nourished Segment and Total Plan Area for Nourishment Sediment Same as Native. Beach Nourishment Conditions Given in Table 4.

I I




C)
I_.
0
CU
c C:
m "0 "0

. . . . . ... I
...................... .................... ....................................................................-

80 70 60 50 40 30 20 10
0

.... ... ......
*.1.lSido A o
-. _.. YA ri

.......... a.S

~~ent
,. -.-' - .-...' ,- -" :
.. ......... .. . ....... .... ........ ........... -" .......". .....'...... .......... ..--..-..
. ..... ... . .. .. .
I I,. "

*~ -'-

Time (years)
Figure 27. Variation with Time of Equilibrium Dry Beach Plan Area Inside and Outside of Nourished Segment and Total Plan Area. Beach Nourishment Conditions Given in Table 4. DN = 0.20 mm, DF = 0.275 mm, oF = 0.2.

93 \- t ........m.......
. . . . .. . . . . . .. . . . .'. . . . .. . .. . ..
DE =:0.275 mm
..2 ...... ..........
0F

T

I

I

I I I I I

I

9




co
a)
1..
CU)
C.)
00 C
a)
m
CU
0
ii V.-

50 40 30 20 10
0

Time (years)
Figure 28. Variation with Time of Equilibrium Dry Beach Plan Area Inside and Outside of Nourished Segment and Total Plan Area. Beach Nourishment Conditions Given in Table 4. DN = 0.20 mm, D. = 0.275 mm, cF = 0.5.

I I i I I I I i
T ota~i i ...............
T tal:. -. T.'.........
................ I .............. ..=...2 0. ..
SDF =:0.275 mm
"- eF = 0.5
. . . . ... . . . . . .. . . . .. . . .. .. .. ... '.. .. . . . .. .. . . . . ..
o.......... ....................
. . . . .... . . .
- A
. . . .... I .
. . . . . . .. . . . . . . . .I . . . I . . . . . . . .




23. Additionally, for future reference, the initial plan area is 0.55 acres decreasing to 0.45 acres after 20 years.
Figure 25 presents the same type of results as in Figure 24 except for a sorting, OF = 0.5. It is noted that the grain size distributions for this case are presented in Figure 16. For this case, the increase in plan area is large compared to that for OF = 0.5. The initial plan area is 11.4 acres contrasted to 0.55 acres for OF = 0.2 and the corresponding plan areas after 20 years are 10.7 acres and 0.45 acres, respectively.
Figure 26 presents the same type results for the case of nourishment with a sediment size equal to the native (DF = DN = 0.2 mm). In this case, the performance of the nourishment project with the methodology adopted is independent of the sorting. The total plan area is 26.2 acres and is invariant with time.
Figures 27 and 28 present results for a nourishment sediment coarser than the native (DF= 0.275 mm) and sorting values of 0.2 and 0.5, respectively. Worthy of note is that the total plan area is substantially larger for these coarser sediments and increases with time.
Table 5 summarizes results from Figures 24-28 and for four other cases not illustrated by figures.
Table 5
Summary of Total Plan Area for
Various Cases Considered, DN = 0.2 mm, Ou4 = 0
Nourishment Sediment Characteristics Total Plan Area (Acres) Case Fig urureN* Size, RF j Sorting,o IFt=0 t=20years
2 4014020.55 0.45
3 50140511.4 10.7
4 S 01 0817.2 16.7
5 20.0Arbitrary 26.2 26.2
6 N* 0250 54.6 67.6
7 7 0.275 0.2 50.5 66.5
8 28 0.275 0.5 39.5 48.3
9 NS* 0.275 0.8 30.3 34.8
*Not Shown as a Figure.




4 SUMMARY AND CONCLUSIONS

4.1 Summary
It has been shown that the nourishment sediment characteristics vis-a-vis those of the native sediments are quite significant determinants of beach nourishment project performance. Whereas previous equilibrium beach profile methodology has been limited to consideration of nourishment sediment sizes represented by a single value, it has been shown that broadening this consideration to a sediment composed of two sizes, one of which is the same as the native, results in more reasonable project performance. Results are presented for a beach nourishment project typical of Florida conditions. For nourishment sediments finer than the native with a sorting of 0.5 and a mean size of 0.14 mm which represents a 30% smaller size than the native size of 0.2 mm, the initial additional beach plan area is 56% less than if the nourishment sediments were totally equal to the native sediment size and at the end of the 20 year period used in these calculations, the total additional beach plan area with the finer nourishment sediments is some 59% less than the project constructed with native sediments (Table 5). A sediment which is 38% coarser than the native with, a sorting of 0.5 results in a 51% increase in total additional beach plan area at the time of construction and a 84% increase after a 20 year period.
4.2 Conclusions
Based on the sensitivity of beach nourishment performance to nourishment grain size characteristics, more effort should be directed in the exploration and design phases to locating high quality beach nourishment material and to evaluating their effects on predicted project performance. Additionally, future research should continue to develop improved design procedures to allow rational incorporation of nourishment sediment size characteristics.
5. REFERENCES *
Bruun, P. (1954) "Coast Erosion and the Development of Beach Profiles", Technical Memorandum
No. 44, U.S. Army Corps of Engineers, Beach Erosion Board.
Dean, R. G. (1974) "Compatibility of Borrow Material for Beach Fills", Proceedings 14th
International Conference on Coastal Engineering, ASCE, Copenhagen, pp. 1319-1333.
Dean, R. G. (1977) "Equilibrium Beach Profiles: U.S. Atlantic Gulf Coasts", Ocean Engineering
Technical Report #12, Department of Civil Engineering, University of Delaware, Newark,
DE.
Dean, R. G. (1987) "Coastal Sediment Processes: Toward Engineering Solutions", Keynote Address,
Coastal Sediments '87, Specialty Conference on Advances in Understanding of Coastal
Sediment Processes, ASCE, Vol. I, New Orleans, Louisiana, May 12-14, pp. 1-24.
Dean, R. G. (1991) "Equilibrium Beach Profiles: Characteristics and Applications", Journal of
Coastal Research, Vol. 7, No. 1, Winter, pp. 53-84.




Dean, R. G., Healy, T., and Dommerholt, A. (1993) "A 'Blind-folded' Test of Equilibrium Beach
Profile Concepts With New Zealand Data", Marine Geology, Vol. 109, pp. 253-266.
Dean, R. G., and Charles, L. (1994) "Equilibrium Beach Profiles: Concepts and Evaluation", Report
No. UFIJCOEL-94/013, Coastal and Oceanographic Engineering Department, University of
Florida, Gainesville, FL.
James, W. R. (1974) "Beach Fill Stability and Borrow Material Texture", Proceedings 14th
International Conference on Coastal Engineering, ASCE, Copenhagen, pp. 1334-1349.
Krumbein, W. C. (1936) "Applications of Logarithmic Moments to Size Frequency Distribution of
Sediments", Journal of Sedimentary Petrology, 6(1), pp. 35-47.
Krumbein, W. G. and James, W. R. (1965) "A Lognormal Size Distribution Model for Estimating
Stability of Beach Fill Material", Technical Memorandum No. 16, U.S. Army Coastal
Engineering Research Center.
Moore, B. D. (1982) "Beach Profile Evolution in Response to Changes in Water Level and Wave
Height", MCE Thesis, Department of Civil Engineering, University of Delaware, Newark,
DE, 164 p.
Stauble, D. K. (1992) "Long-Term Profile and Sediment Morphodynamics: Field Research Facility
Case History", Technical Report CERC-92-7, U.S. Department of the Army, Coastal
Engineering Research Center, Waterways Experiment Station, Vicksburg, MS.
U.S. Army, Corps of Engineering (1984) "Shore Protection Manual", Coastal Engineering Research
Center, 2 Volumes, Vicksburg, MS.