EM 1110-2-1100 (Change 1)
31 Jul 03
SEAS
Waves caused by wind at the place and time of observation.
SEASHORE
(1) (Law) All ground between the ordinary high-water and low-water mark. (2) The shore of the sea or ocean, often
used in a general sense (e.g., to visit the seashore).
SEAWALL
(1) A structure, often concrete or stone, built along a portion of a coast to prevent erosion and other damage by
wave action. Often it retains earth against its shoreward face. (2) A structure separating land and water areas to alleviate the
risk of flooding by the sea. Generally shore-parallel, although some reclamation SEAWALLS may include lengths that are
normal or oblique to the (original) shoreline. A SEAWALL is typically more massive and capable of resisting greater wave
forces than a BULKHEAD.
SECHHI DISK
Visibility disk (white and black, 30 cm diameter) used to measure the transparency of the water
SEDIMENT
(1) Loose, fragments of rocks, minerals or organic material which are transported from their source for varying
distances and deposited by air, wind, ice and water. Other sediments are precipitated from the overlying water or form
chemically, in place. Sediment includes all the unconsolidated materials on the sea floor. (2) The fine grained material
deposited by water or wind.
SEDIMENT CELL
In the context of a strategic approach to coastal management, a length of coastline in which interruptions to the
movement of sand or shingle along the beaches or near shore sea bed do not significantly affect beaches in the adjacent
lengths of coastline.
SEDIMENT SINK
Point or area at which beach material is irretrievably lost from a coastal cell, such as an estuary, or a deep channel
in the seabed.
SEDIMENT SOURCE
Point or area on a coast from which beach material is supplied, such as an eroding cliff, or river mouth.
SEDIMENT TRANSPORT
The main agencies by which sedimentary materials are moved are: gravity (gravity transport); running water
(rivers and streams); ice (glaciers); wind; the sea (currents and LONGSHORE DRIFT). Running water and wind are the
most widespread transporting agents. In both cases, three mechanisms operate, although the particle size of the transported
material involved is very different, owing to the differences in density and viscosity of air and water. The three processes
are: rolling or traction, in which the particle moves along the bed but is too heavy to be lifted from it; SALTATION; and
suspension, in which particles remain permanently above the bed, sustained there by the turbulent flow of the air or water.
SEDIMENT TRANSPORT PATHS
The routes along which net sediment movement occurs.
SEEPAGE
The movement of water through small cracks, pores, interstices, out of a body of surface of subsurface water. The
loss of water by infiltration from a canal, reservoir or other body of water or from a field. It is generally expressed as flow
volume per unit of time.
Appendix A Glossary of Coastal Terminology
A-69
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