IV. Retreating Shorelines
223
Beach nourishment has been considered a potentially desirable form of shore
protection. It is beneficial as wave action spreads the material along the
shoreline. Costs have been lowered by use of booster pumps allowing long
distance material piping, and the use of hopper dredges which can dredge,
deposit pump and transport. Navigation channel maintenance dredged material
can be used for beach restoration. Hence both deposition of sand and beach fill
are suitable techniques. Beach nourishment is constant with natural coastal
processes, augments the natural transport of coastal sediments and use of dredged
material keeps it into the littoral system. No substantial biotic effects have been
observed.
3.1.1
Hard and Soft Approaches
The earliest beach nourishment project may well have been the dredging, in
1920, of Santa Barbara, CA harbor and deposition of the material on the eroded
beach downcoast of the breakwater ~9a.
White reported that with beach nourishment involving over 2.500.000 m 3
(3.280.000 cu.yd) of material deposited over three years the beach original fauna
was destroyed but a new fauna has developed 19. Assessments of artificial
nourishment of beaches have been made for over thirty years and are still carried
out on a frequent basis 2°.
Segmented offshore breakwaters were built based on the premise that direct wave
pounding on the beach would be attenuated, cause a transformation of the
incoming waves and induce deposition of drifting sediment in the lee of the
structures (fig. 31). The ensuing beach salient may even become connected to the
breakwater segment and form a tombolo.
Wave energy is reduced in the spaces between the successive segments as well. A
beach is thus constructed but a certain amount of sand is removed thereby from
the longshore transport system.
Beach nourishment has been eyed by the U.S. Army Corps of Engineers as a
method to dispose of the 265.5 million m 3 (300 million cu.yd)of dredged
material it picks up annually. This material is usually dumped at sea damaging
benthic life. Such disposal can also help portuary development and marsh
creation. Under the proper circumstances the use of dredged material for beach
nourishment not only contributes to the development and maintenance of
waterway transportation, but also provides hazard reduction and recreational
benefits consistent with environmental mandates and the material laws governing
coastal systems.
223
Beach nourishment has been considered a potentially desirable form of shore
protection. It is beneficial as wave action spreads the material along the
shoreline. Costs have been lowered by use of booster pumps allowing long
distance material piping, and the use of hopper dredges which can dredge,
deposit pump and transport. Navigation channel maintenance dredged material
can be used for beach restoration. Hence both deposition of sand and beach fill
are suitable techniques. Beach nourishment is constant with natural coastal
processes, augments the natural transport of coastal sediments and use of dredged
material keeps it into the littoral system. No substantial biotic effects have been
observed.
3.1.1
Hard and Soft Approaches
The earliest beach nourishment project may well have been the dredging, in
1920, of Santa Barbara, CA harbor and deposition of the material on the eroded
beach downcoast of the breakwater ~9a.
White reported that with beach nourishment involving over 2.500.000 m 3
(3.280.000 cu.yd) of material deposited over three years the beach original fauna
was destroyed but a new fauna has developed 19. Assessments of artificial
nourishment of beaches have been made for over thirty years and are still carried
out on a frequent basis 2°.
Segmented offshore breakwaters were built based on the premise that direct wave
pounding on the beach would be attenuated, cause a transformation of the
incoming waves and induce deposition of drifting sediment in the lee of the
structures (fig. 31). The ensuing beach salient may even become connected to the
breakwater segment and form a tombolo.
Wave energy is reduced in the spaces between the successive segments as well. A
beach is thus constructed but a certain amount of sand is removed thereby from
the longshore transport system.
Beach nourishment has been eyed by the U.S. Army Corps of Engineers as a
method to dispose of the 265.5 million m 3 (300 million cu.yd)of dredged
material it picks up annually. This material is usually dumped at sea damaging
benthic life. Such disposal can also help portuary development and marsh
creation. Under the proper circumstances the use of dredged material for beach
nourishment not only contributes to the development and maintenance of
waterway transportation, but also provides hazard reduction and recreational
benefits consistent with environmental mandates and the material laws governing
coastal systems.