IV. Retreating Shorelines
1 g9
Little attention, however, had, in the planning, been paid to possible negative
consequences on beach evolution and marine erosion. Harbor extensions, or
outright port creation, whether for industrial purposes, or for marinas, led to
extensive dredging of access channels, construction of dams on rivers,
particularly in estuaries, and/or large scale retrieval of bottom material for
construction works with the concomitant risk of important reductions in bed load
material, material thus withdrawn from the natural supply of sand needed to
resupply the beach 1°.
Beaches, unconsolidated littorals, are in constant evolution. Continued
surveillance, e.g. sedimentary dynamic study of the area, impact study prior to
any new modification implementation, on the shoreline, is required. Coast
defense against erosion, accretion diminution, hightide dry beach area shrinking,
has heretofore induced engineers to construct protective structures. In several
countries such counter measures meant building of groins, detached breakwaters
or similar construction works (Belgium, The Netherlands, Great Britain, Italy,
U.S.A ..... )11.
In the United States due to the absence of eminent domain on several coasts,
governmental help, until rather recently, was excluded. This resulted in the
building of make-shift breakwaters, which were often inefficient, highly
temporary and eyesores 12.
Hoping to stop drastically erosion-induced problems, here local authorities, there
private developers, often built sea-walls, dams or other similar "hard" defenses,
yet, these in turn while providing some local relief, increased erosion in spots
because of reflection, currents, overtopping, scouting and other dynamic
phenomena.
During the last decades, beach nourishment, viz. artificial accretion, has been
called upon as a coastal protection method, a "soft", in contrast to "hard
medicine". Such an approach has been followed in Belgium with the beach
replenishment project at Knokke-Heist, near the Dutch border. A beach
renourishment project involving sluicing of about 8.4 million m 3 (11.2 million
cu.yd) of sand was executed along the eastern part of the Belgian coast between
Zeebrngge and the Dutch border ~3. Further nourishment plans have been
undertaken on the west coast (Nieuwpoort vicinity) and at De Haan (a.k.a., Le
Coq).
Completed in 1979, the east coast works covered a stretch of 8 km (5 mi), which
meant a supply of rather more than 1,000 m 3 (1,313 cu.yd) of sand per running
meter (400 cu.yd/ft). The beach itself was widened by about 100 m (325 ft) ; in
some places it required the construction of an entirely new beach.
1 g9
Little attention, however, had, in the planning, been paid to possible negative
consequences on beach evolution and marine erosion. Harbor extensions, or
outright port creation, whether for industrial purposes, or for marinas, led to
extensive dredging of access channels, construction of dams on rivers,
particularly in estuaries, and/or large scale retrieval of bottom material for
construction works with the concomitant risk of important reductions in bed load
material, material thus withdrawn from the natural supply of sand needed to
resupply the beach 1°.
Beaches, unconsolidated littorals, are in constant evolution. Continued
surveillance, e.g. sedimentary dynamic study of the area, impact study prior to
any new modification implementation, on the shoreline, is required. Coast
defense against erosion, accretion diminution, hightide dry beach area shrinking,
has heretofore induced engineers to construct protective structures. In several
countries such counter measures meant building of groins, detached breakwaters
or similar construction works (Belgium, The Netherlands, Great Britain, Italy,
U.S.A ..... )11.
In the United States due to the absence of eminent domain on several coasts,
governmental help, until rather recently, was excluded. This resulted in the
building of make-shift breakwaters, which were often inefficient, highly
temporary and eyesores 12.
Hoping to stop drastically erosion-induced problems, here local authorities, there
private developers, often built sea-walls, dams or other similar "hard" defenses,
yet, these in turn while providing some local relief, increased erosion in spots
because of reflection, currents, overtopping, scouting and other dynamic
phenomena.
During the last decades, beach nourishment, viz. artificial accretion, has been
called upon as a coastal protection method, a "soft", in contrast to "hard
medicine". Such an approach has been followed in Belgium with the beach
replenishment project at Knokke-Heist, near the Dutch border. A beach
renourishment project involving sluicing of about 8.4 million m 3 (11.2 million
cu.yd) of sand was executed along the eastern part of the Belgian coast between
Zeebrngge and the Dutch border ~3. Further nourishment plans have been
undertaken on the west coast (Nieuwpoort vicinity) and at De Haan (a.k.a., Le
Coq).
Completed in 1979, the east coast works covered a stretch of 8 km (5 mi), which
meant a supply of rather more than 1,000 m 3 (1,313 cu.yd) of sand per running
meter (400 cu.yd/ft). The beach itself was widened by about 100 m (325 ft) ; in
some places it required the construction of an entirely new beach.