EM 1110-2-1100 (Part V)
31 Jul 2003
4
Dune Crest Elevations
4.0 m
4.5 m
2
0
-2
0
25
50
75
100
125
Calculated Erosion
4
4
Pre-Storm Profile
Post-Storm Profile
2
2
0
0
4.0-m Dune
4.5-m Dune
-2
-2
0
25
50
75
100
125
0
25
50
75
100
125
Distance from Baseline, m
Figure V-4-13. Example of storm-induced beach erosion as a function of dune crest elevation
on depth of closure). Whereas dune and berm dimensions are determined through optimization, the
shape of the design profile below the beach berm is a function of the local morphology and grain size of
the fill. Local beach morphology often includes a nearshore bar system, which may be absent in erosion-
stressed preproject beaches. In such cases, a berm also might be absent from the profile, or may be
unnaturally low in elevation; or the preproject profile may reflect an overly steep beach face. A key aspect of
defining the design profile shape is to recognize whether or not the preproject beach reflects an unnatural,
sediment-starved condition, in which the preproject shape is different from that which will evolve once
the fill is placed. For example, a severely eroded beach may lack the commonly observed nearshore
bar system, but the bar system will likely form under sediment-rich conditions that follow
nourishment. Consequently, the sectional fill volume should include an estimate of bar volume. In these
situations, design profile shape can be defined by examining nearby beaches that are healthier in terms of
available sediment supply (from the upland beach and from longshore sources). Profile data from adjacent
beaches within the project domain, or data from a nearby site that is exposed to similar wave and
Beach Fill Design
V-4-33
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