12 December 2001
COASTAL GEOLOGIC MORPHOLOGY. Classification of coastal
geology and geologic character is of great importance to coastal engineers because of
the complexity and diversity of the coastal environment. Section IV-3 of the CEM
describes the historical emergence of coastal geologic classifications and summarizes
the current preferred classifications and their influence on contemporary coastal design.
COASTAL MORPHODYNAMICS. The discussion of coastal
morphodynamics in Section IV-4 of the CEM states that coastal landforms are the result
of the interactions of many physical processes, man-made influences, global tectonics,
local underlying geology, and biology. Significant to the coastal designer is the fact that
the physical conditions along the coast are constantly changing in response to many
processes and often, in a relatively limited area, influence the formation of a
combination of the four types of coastal environments: deltas, inlets, sandy shores, and
cohesive shores (CEM, Section IV-4).
FOUNDATIONS AND ANCHORING. Seafloor conditions and materials
must be considered when placing structures and establishing an area for anchorage.
Considerations for seafloor foundation design are discussed in Section VI-3-1 of the
CEM. "Scour" occurs where sediment is eroded from beneath or around a structure's
foundation making it susceptible to failure. A summary of this process and its effects is
found in the Handbook for Marine Geotechnical Engineering, edited by K. Rocker
(Naval Civil Engineering Laboratory (NCEL), 1985). Additional design considerations
regarding sediment transport are discussed in Section III-1-1 of the CEM.
Anchoring. Selection of anchor type is based on bottom conditions.
Information on this subject is also contained in the "Handbook for Marine Geotechnical
Engineering" (Rocker, 1985). Where possible, locate the anchorage over a bottom of
loose sand or gravel, clay, or soft coral. Avoid locations where the bottom consists of
rock, hard gravel, deep mud, and deep silt.
SEDIMENT BUDGET. Sediment budget is based on the principle of
continuity or conservation of mass as applied to coastal sediments. A discussion of the
processes and methods of evaluation are found in Section III-2-3-g of the CEM.
Related information concerning wind blown sediment transport is contained in Section
III-4-5-c of the CEM.
EFFECTS OF STRUCTURES ON SEDIMENT TRANSPORT. Man-made
structures have a significant influence of sediment transport mechanisms. Groins,
seawalls, jetties, breakwaters and piers all affect sediment transport and deposition
processes. Numerous examples given in Sections III-2 and III-3 of the CEM indicate
that the effect of these man-made structures on sediment deposition is significant in
coastal engineering design. These effects can often be a source of technical data
when investigating sediment transport.
MATERIAL PROPERTIES. Sediment transport and deposition occur on
open coasts, in tidal inlets, in estuaries, in harbors, and in rivers. The types of
sedimentation problems that occur at each of these locations depend, in part, on the