EM 1110-2-1100 (Part V)
31 Jul 2003
Spring 1
8
Fall 1
Spring 2
Fall 2
6
4
2
0
0
20
40
60
80
100
120
Distance from Baseline, m
Figure V-4-10. Seasonal variation of a beach berm
(d) In cases where no dry beach exists at the project site, or where the existing beach has a deficit of sand
due to substantial reduction or elimination of a critical sediment source, such as in front of a seawall or
downdrift of a shore-perpendicular structure, the natural berm elevation should be estimated using profile data
from adjacent beaches which are healthier in terms of sand availability but are exposed to similar waves and
water levels. Priority should be given to identifying a natural berm elevation using beach measurements from
the project site or a similar site. As a last resort, when no suitable beach profile data are available to
determine a natural berm height, the limit of wave runup under average (nonstorm) wave and tide conditions
at the site can be estimated to establish a design berm height (see Part II-4-4 for calculation of wave runup
on beaches).
(2) Berm width.
(a) Selection of the design berm width depends on the purpose of the project and is often constrained by
factors such as project economics, environmental issues, or local sponsor preferences. For Federal beach
nourishment projects, the berm width is determined through a process of optimization based on storm damage
reduction. The design beach width is optimized by computing costs and benefits of various design
alternatives and selecting the alternative that maximizes net benefits (USACE 1991). Numerical models of
beach profile change such as Storm-Induced BEAch CHange (Larson and Kraus 1989) provide a means of
evaluating beach response as a function of berm width. Figure V-4-12 illustrates how berm width influences
the landward extent of erosion during a storm. Figure V-4-12a shows four beach profiles with identical dune
Beach Fill Design
V-4-29
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