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Group Title: UFLCOEL-2000002
Title: Beach nourishment design
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Permanent Link: http://ufdc.ufl.edu/UF00091070/00001
 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
Physical Description: vii, 41 leaves : ill. ; 28 cm.
Language: English
Creator: Dean, Robert G ( Robert George ), 1930-
Florida -- Office of Beaches and Coastal Systems
Publisher: Coastal & Oceanographic Engineering Program, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 2000
 Subjects
Subject: Beach nourishment   ( lcsh )
Sand -- Sampling -- Mathematical models   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (leaves 40-41).
Statement of Responsibility: prepared by Robert G. Dean.
General Note: "February 23, 2000."
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Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
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Resource Identifier: oclc - 49575830

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Page i
    Executive summary
        Page ii
    Table of Contents
        Page iii
    List of Figures
        Page iv
        Page v
        Page vi
    List of Tables
        Page vii
    Main
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
    Reference
        Page 40
        Page 41
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. O. 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 0.41.








TABLE OF CONTENTS


EXECUTIVE SUMMARY .................................................. ..... ii

LIST OF FIGURES ................................. .................... iv

LIST OF TABLES ................. ...................................... vii

1 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 Granulometric 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 Summary ........................................................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 min. To Convert to ft"3, 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, Ay/W., with A' and V.
Results Shown for B' (=B/h.) = 0.5 (Dean, 1991) ............................. 16

12 Variation of Non-Dimensional Shoreline Advancement, Ay/W., with A' and V.
Results Shown for B' (=B/h.) = 0.25 (Dean, 1991) ........................... 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, D, = 0.275 mm, D = 0.2 mm, D, = 0.14 mm .................. 20

15 Example of Nourishment with Two Sediment Sizes, V, = V2 = 160 yd3/ft, DN = 0.20
mm, DF = 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, N = 0.0, 0,F= 0.5 ..................................... .24

17 Fraction of Coarser Portion, Fi, 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 VTT = 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, D = 0.275 mm, N = 0.0, OF= 0.5 ...................................28

20 Fraction F,, and Mean Diameter, DF,, 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, F= 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
Table4. DN= 0.2mm,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 =0.20 mm, DF =0.275 mm, F= 0.2 ............................. 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 =0.275 mm, ao = 0.5 .............................38








LIST OF TABLES


TABLE PAGE

1 Correspondence Between Sediment Sizes in mm and () Units ..................... 3

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 .................... 7

3 Summary of Recommended A Values (ft03) for Diameters from 0.10 to 1.09 mm ..... 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 focuses 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 (() scale

S= 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

c 0.7

0.6
a)
iL 0.5
0
o 0.4

S0.3


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 $ Units

Sediment Sizes

) 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


1 202
f(7) e
V2~;o


where a is the standard deviation of the distribution (also called the "sorting") and p is the mean of
the distribution, also in ( units. For well-sorted sediments, ao0.5 and for poorly-sorted sediments
o 1.0. Sediments which are "well-sorted" and "poorly-sorted" are also referred to as "poorly-
graded" 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%

co
.c 90%
1-
a 70%
iT 50%
c 30%

a-
S 10%

1%

0.1%

0.01%
0.001%


..... .. ..... ............... ........................................................... ........................... .

..... .. ..... ...... ........................ .................................................


Approximate Best Fit Line



*0*.*
................................ ... ............ ... ................... .. ..........

S.. ... .......................----- ...*....... ..- .. -

......... ................ .... ........ .. ...... .... ....... ....... .. ....... ....
S...........:.: ...............


"'-.. i ...........
... ........................"...".... .......................... ................. %..........

............................................................................... .............................
. ................. ................................................................ ...........................
*"* *

. ...... ... .. ... .. ... ........ .. . .. .......... ... .. ... ..... ... .. ....... . .. :. ............ .. .... .. .. .... .. ... .... . :. ..,... .. .... ... ... .. : . .... ... .'


Coarser Z Finer
--"-- Grain Size in ) 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, Pp/op, and non-dimensional mean of the native, lN/op. Here
subscripts "F" and "N" denote "fill" and "native", respectively.











3.01 02 0.4 06 08 1.0 2.0 3.0
-- ,1 ///^. ,i/, -


,o -9 /. / ib


/ Note: -/










Figure 3. Overfill Factor, K, Based aviation Measurthod Developed by Dean
0.2 0.4 06 08 1.0 20 3.0



Q1 OA 06 08 1.0 2.0 3.0



Figure 3. Overfill Factor, K, Based on Method Developed by Dean
(1974).








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
4.8
W | -
3.0


2.0 values ofR,




1.2 02
















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
0.6




















overfill factor is 3.09 as presented in Table 2. For the same size distribution, the overfill factor
0.




0.2
-4 -3 -2 -1 0 I 2 3 4



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.





























L ---4 7- 1 7 7
......
.........
----


1.0 0 1.0 2.0 3.0 4.0


1F-AN

'UN
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))


4.0 -
Saues of R

3.0 t e

2.5


it -ti-t.t*, ,J


0


0.21
-4,


~s 7


--


.v


#*;,:r


lA F I I I..








Grain
4 2 I 0.5
I I I I I


Size (mm)
0.2
I I


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)y23 (4)

in which h represents the water depth at a distance, y, from the mean water line and A(D) is a so-
called 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 sediments 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) =h3(y) + A/ (y ( -yj)J ,yJ< YJ+1 (5)


where the sediment scale parameter, A, is now piecewise uniform across the profile and Aj is the
value of the sediment scale parameter between y, and yj+i. 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


S Sand Moves Offshore to
Equilibrate Profile



-Nourished Shoreline


S--"Spreading Out" Losses

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


Dry Beach W
(Fine Sand)


Dry Beach Width (Coarse Sand)

- Initial Placed Profile

S-Equilibrated Profile (Coarse 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
Suggested Empirical
Relationship A vs. D
(Moore) -
From Hughes'
.. Re esuts7 -
From Individual Field / A= w
Profiles where a Range
of Sand Sizes was Given
0.10
A ^^ Based on Transformnning
A vs D Curve using
Fall Velocity Relationship

S-_ From 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'", Multiply by 1.486 (Dean, 1987).















Table 3
Summary of Recommended A Values (ft1") for Diameters from 0.10 to 1.09 mm


D(mm) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09

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

1.0 0.3121 0.3132 0.3144 0.3156 0.3168 0.3180 0.3192 0.3204 0.3216 0.3228











-3 I I.
2 4.0 E
-1 2.0
w 0 -- .--.^- L --- ( 1.0 w
S70.5
2 1 0.25

5 0.031

STANDARD





0 100 20 30 400 500 600 700 90 EVTIO 1000






DISTANCE FROM BACKSTAGE (m)
Figure 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.


For those cases in which the nourishment and native sediments can each be represented by
a single size, Dean (1991) has shown that there are three types of nourished profiles: intersecting,
non-intersecting and submerged as shown in Figure 10. The variables were cast in non-dimensional
forms including the following: the additional dry beach width, Ay/W., in which Ay is the additional
dry beach width of the equilibrated profile and W. is the width of the beach profile out to the closure
depth on the native profile, i.e.,



= h,/2 (6)



in which AN is the sediment scale parameter for the native sediment. The non-dimensional shoreline
advancement can be expressed as


Ar B(7)
W B f (7)
W. BW. AN' h.















Added Sand


Added Sand -

b) Non-Intersecting Profile


-1


Nourished Profile


Added Sand-*
c) Submerged Profile AF
Figure 10. Three Generic Types of Nourished Profiles (Dean, 1991).







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), ao. 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 oc, respectively are represented by Eqs. (8) and (9).

1 i
=1 Pi (8)
I i=1


I N 1/2
=^ o2+- -( i-c)2 (9)
I i=l I i=l


Eq. (9) can also be represented as

= 02 + I)2 ]12
c I 2 1 E 2112(10)
i=1 I i=1 I2 i=1








































0 1.0 2.0 2.8
A'= AP/AN



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 ,_'- ,_

A "0.01 -

Asymptotes




I!;, i _ _ --


, __--..--- --,-- .-- --
1 *o
-p=^== r -- -----









RslsSoDefinition Sketch) =.25(n. 91.
0.0001
1.0 2 .,oo .02







DefFigure 12. Variation of Non-Dimensional Shoreline Advancement, AyW, with A' and V'.
Results Shown for B' (=Bh) = 025 (Dean, N 1991).


A'= AFIAN

Figure 12. Variation of Non-Dimensional Shoreline Advancement, 'y/W, with A! and VI
Results Shown for B' (=B/hi) = 0.25 (Dean, 1991).



















0 100 200 300 400 500
Offshore Distance (m)


600 700


a) Measured Sediment Sizes, Dso%, (mm)
Averages for 165 Florida East Coast Profiles





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

........ M measured. ......... ....... ..... . ............
........ ..... .. .. ...... ... .....

................. ........... ...........

.i... Calculated
..... .....i.......
... ... .. ... ... . .. ... .. .. ... ... .. ... .. ... ... . .. ..


0 100


200 300 400 500
Offshore Distance (m)


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 m 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


_:::::: .............
...................... .......I---w- D50%, (mm)j


...................... ........... ..................... ... (79)

- i...... .......... I: :: I:


0






-5






-10








Application 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


WiPi
i=1
PC -i I (11)
wi





i=l i=l
o = /2(12)

Ewi wi
i=1 i=l



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 11 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 = 0.2 mm

4 0 0 ................................. ................................... .................... ............
400 .

E
(D
300



1 200 ... ...
O

00


0
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, DF, = 0.275 mm, D, = 0.2 mm, D3 = 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


(F e -(41.-pF)22o

+ erf (13)




where 4. represents the value of ( 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 -(k4-F)2/2
-=e

Fh+ t o F + (14)
r1 erf z -



The fraction of material which has the same grain size as the native is








1 -
10






0





*- -10 -
(0

t",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, D, = 0.20 mm.


3000









F 1 +erfj (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 (. for this case is
2.66(, the mean of the fraction considered to reside offshore, p2 = 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 2 -(2.-PF)2G

N= =f + 1 fI (16)
1 erf



where erf is the so-called "error function" and (. represents the value of ( 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, pFq, is given by


----F e -( F)2

PF, 1F 1 + erf (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
......... ..........................................-------- -------
1.8



Native: Sediment

1 .2 .........i... e.... : ........ ......... ........ ... ..... ... .... ...... . .. .
1.4

=1.2 2.32w Average.ofNourishment
.. Sediment 2.74 (p

4- E
0 .8 ..... ............. ................... ...... '. ..... .. ............ ....................



0. .. .. ...... ............. ..............0....
0.6 ......................................... ... -

o. ------- .......................- -................... .-l I............................

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, F = 0.5







1.0 I

o.g 4 m r.......... _...=. ........: .......................
0.9 .....--------------------------------------------





0.5

0 .4 .............

0.3

0.2

0 .........................

0.0
0 1 2 3 4
Sorting of Nourishment Sediments, aF

Figure 17. Fraction of Coarser Portion, Fi, and Mean Diameter of Finer Portion Dm, as a Function of Sorting of Nourishment Sediments.







100

S 90 D-=-020 mm .................... --------
N
S0 .. = Om m ...... ....................................... .........................
80 F
7 .0 .-................ ................ .................

0
i




0 20
Cr
M 0 ~ ~40 .......................- -- --- --- -- --- --




*0





Sorting of Nourishment Sediments, 3F

Figure 18. Volume of Shoreline Displacement, Ay as a Function of Sorting of Nourishment Sediments for VTOT = 100 yd3/ft.









F2 1 -erf'i (18)
2 2F2 (7)

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 mm 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, t. was
found by iteration (4, = 1.995), the mean size of the inshore sediments is p,, = 1.52 ) (DFp = 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 yd3/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

1.6

1 .4 -- ---..................... ...---- --. --. -. .. .. .................... ..... ...... .............
(D.4
0.2 -








Figure 19. Illustration of Method for Determining Portion of Nourishment.......... Sediments with Mean Size Equal to the Native for Nourishment...........................................
Sediment = 1.8 05 m
S 1 .0 ......... ........................... .... ........
.. .. Native Sediment
S............................................ ........ ...................
o0.8o ." ...... ......W

o ...... .. ......... .........................
0 .6 .-. ......-. .... -- -------- ........ ..

0 .2 -....... ......... ............. ................. ....... .... .. ..... .





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, ON = 0.0, OF = 0.5.









0.9 5 mm
10.
0 .9 .. .. .. .. .. .. .. .. --------- -- :- -
SD, = 0.275 mm
0.8. ...... .. -..... . ..................... .......... .............................

S0.7- .........----.

0.6 -3---

0.5

0.4 ...

0.3

0.2 \. . .



0.0
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 ......... ..... ... ......Dmm.............. ......................
DF = 0.275 mm







80
o 160.. ..............................................................-











Disp3 Feb 9, 2000 7:58:18 PM
0 0



0 1 2 3 4

Sorting of Nourishment Sediments, aF

Figure 21. Volume of Shoreline Displacement, Ay as a Function of Sorting of Nourishment Sediments for VTor = 100 yd3/ft.
C
C 5




0 ---------------------------




Figure 21. Volume of Shoreline Displacement, Ay as a Function of Sorting of Nourishment Sediments for VTOT = 100 yd~lft.







500


400JN "" -I I"

-r 4 00 ........................... .. .... .. .......... . .. .
C-






S 0 0 ........................... .................. ... ... . ..............

0 . ----- -- ---





0 100 200 300
(O..




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


4< 4 0
-- 30 0 .................................. .............. ....... .......


4 00 .. .... .. ... .- ...... ... .......
S 00 .............. .........




3 0 -- -- -- ....----- - -
0
o /""...
O 10 ... ... ................4. .... :.: .............. .
L-L~







0 100 200 300
Volume Density (yd3/ft)


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








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
planform 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


Project Length 2 miles
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


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, ,F = 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












..................... .......... ..........
. _ _ 1 T' t at 1


0




L...



c
QU

0




C
0


-<
:5


0.6



0.5



0.4



0.3



0.2



0.1



0.0


loe


''**
S. .

. . . . . ..


.. .. ......... ....... ... ... . .... ... ... ....... ..

: D = 0.20 m-

S.. ..=..4m...m......

oF = 0.2

I, i-, I ,, 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, op = 0.2.


{'jsioe
%0Lir


S/1e4 Se


___ I __


-- -- --


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



.... ......... .................................o


...........








") ToEal
S------.- ....... .. .Total
<--- \ ------------
< 1 0 - .......... ....... .... .......... : ......... .......... .. ....... .... ...... .......... .. ........
D = 0.20 mm

sid1e ,o. DF = 0.14 min


6 8 : . . ... -- ..... .....



6 ..S e..- .....

M 4 6 8 10 1 ..14 16 18 2.......... .0.. ......... ..........
"O /***




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, op = 0.5.









C,

(1)
L







0
CO





-8



O


.o

0


.



. . . .


10


/
/


Total







.... ... -- -- - -- -- -- - -- - D7 - -- 7 2 -- - --- - -
W. .*........ .. .. ................... ..........................
: ""* **^Segs ; i i ;
i i . ....
: : : : : : "" :- .... ,.
: meO 1 ._ .---

......... .... ... o vj .s .. .- .- . ... ............ D ------i .:.: . .. ...........


Dp =0.20 mm

SO F=:0.0
I O.O

I 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 ~ ~__r __ Lr _


_


1











c-
L(D









,U






"0
c











0
c,
0a

'-
T3
l0


SI I I I I I I I


........ ........................................................................................................


80


70


60


50


40


30


20


10


0


. ... ..-. ... .........: .


S1sid No
-.o Jlol
hrk


-.-., ..... aSeg
-


:" .' -"... .
-............................. ................
I I,. ,
.< t







*-~ -'-


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, op = 0.2.


-ol --------'"0"" 0.20 rmm
. ,. ..*. ..... . ..... .. ......... .. . ." D F = 0 :....... .. ... ........ .

DE = 0.275 nmm

'''''':'''''` ''''~'''~'''' ~ :' oiS = '0;'' 2---


T


I I


1


I I I I I


I


_


-


9








Co
a)








C)
S.r










00
a)
m
-U
0
"O5
c

<


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. D = 0.20 mm, D, = 0.275 mm, oc = 0.5.


o t -. ., TotalL. .-....-."


-":"...... . .... ... ...... ....... ............ ..D N.= :0 .20 r m -
SDF =:0.275 mm

"- -UF = 0.5
--- ... -
S......... . ..... ..............




-- o
S. .. . ' .

. . ....
.. . . .. I .
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 (D =
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, oN = 0


Nourishment Sediment Characteristics Total Plan Area (Acres)
Case Figure
Size, piF Sorting, ao t= 0 t = 20 years
1 NS* 0.14 0 0 0

2 24 0.14 0.2 0.55 0.45

3 25 0.14 0.5 11.4 10.7
4 NS* 0.14 0.8 17.2 16.7
5 26 0.20 Arbitrary 26.2 26.2
6 NS* 0.275 0 54.6 67.6

7 27 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. UFIUCOEL-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.




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