EM 1110-2-1100 (Part V)
31 Jul 2003
EXAMPLE PROBLEM V-4-5
FIND:
Volume per unit length of shoreline required to widen the dry beach by 30 m. Disregard any
volume necessary to makeup for a preproject sediment deficit in the beach profile.
GIVEN:
Berm height of 2.5 m and depth of closure of 6 m. Native sand median grain size of 0.27 mm
and fill sand median grain size of 0.18 mm.
SOLUTION:
Values of the A parameter for native and fill sand are read from Table III-3-3.
AN = 0.119 m1/3, AF = 0.094 m1/3
Profile is nonintersecting because AF <AN, therefore Equation V-4-9 is applicable.
Equation V-4-9 gives
3/2 5/3
5/2
3
6
0.094
' 796 m 3/m
V '30@2.5 % @
@ 0.119@ 1 % 30@
& 0.094
5
0.094
6
By comparing with Example V-4-3, it is seen that using the finer material specified in this example
requires 3.1 times the volume required using compatible material to generate the same equilibrium beach
width. This example illustrates that much higher fill volumes are required when using finer-than-native
sand to obtain a given beach width, which is consistent with sand compatibility calculations performed
using the overfill ratio (see Example V-4-1).
Although alongshore spreading of fill material represents a loss to the project area, this material is in most
cases transported to adjacent beaches. Nearby beaches, particularly those downdrift of the project, realize
protective benefits from the neighboring project. Over the life of a beach nourishment project, adjacent beach
benefits can be quite significant. If the project is built adjacent to an inlet with navigation channels, the
impact of the nourishment project on channel operation and maintenance should be assessed.
(1) Periodic renourishment. Beginning immediately after construction, fill material will be lost from the
project due to lateral spreading. Periodic renourishment will be required to maintain the desired beach cross
section. It should be recognized by the designer that year-to-year loss rates can deviate from the long-term
average erosion rates. In addition to end effects at transitions, losses are significantly influenced by the
occurrence of major storms. Annual losses will likely vary from year to year because of the dependency on
storm activity. Therefore, while an average renourishment interval and quantity can be estimated, the actual
Beach Fill Design
V-4-47
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