IV. Retreatin~ Shorelines
217
Researchers at Scripps Institution of Oceanography at La Jolla CA placed 300
units of seascape in service in November 1986, with the cooperation of a member
of the staff of Seascape, an artificial weed manufacturing company. Three B rows
were placed 2 m (6 ft) apart. Previous experience had already led to a
substantiated report.
The experiment disclosed the possibility of an additional "handicap to an already
long list" : fouling of the artificial seaweed by the natural variety where it is
present T It showed no measurable effect of the seaweed on seasonal erosion
losses, and burial of the fronds within a few months due to anchor-induced scour
around their base.
In vitro experiments have not been encouraging : at Wallingford (U.K.) onshore
transport was retarded by artificial seaweed and the U.S. Army Corps of
Engineers, at Fort Belvoir VA, found 12% wave height attenuation for short
period waves only which account for only a minor part of ocean energy.
Commercial brands of artificial seaweed include Seascape, Linear Composites,
Sea Leaves and Sea Grid. The Ruhr Universit~it (Bochum, Fed. Rep. Germany)
developed the IMRA system in 1981.
Conclusions reached for artificial reefs cannot be necessarily extrapolated for
natural seaweed formations : these have in their stalks gas filled floatation
nodules that make them more buoyant and have much longer fronds. Natural
seaweeds do retard water motion and move more as compared to wave oscillation
making them more effective.
Besides artificial and natural reefs schemes, proposals have also been made to
place structures or "sparks" to promote aquaculture or myticulture. These
arrangements can play a simultaneous role in coastal protection.
Marsh grasses have been effectively used to control erosion along estuarine
shorelines. At sites with relatively low wave activity, marsh and low cost
breakwater can offer protection at significantly lower cost than several erosion
control alternatives. Rogers based his conclusion on over 25 years of
observations. [M. Rogers Jr, 1989, Erosion Control : marsh and low cost
breakwaters : Coastal Zone '89, I, 781-764]. Successes are numerous but failures
have also been common.
Success has been attained along shorelines that have fringed marshes but were
denuded (viz. stripped).
The recolonization by planting appropriately can re-establish a marsh in two or
three years, rather than decades.
217
Researchers at Scripps Institution of Oceanography at La Jolla CA placed 300
units of seascape in service in November 1986, with the cooperation of a member
of the staff of Seascape, an artificial weed manufacturing company. Three B rows
were placed 2 m (6 ft) apart. Previous experience had already led to a
substantiated report.
The experiment disclosed the possibility of an additional "handicap to an already
long list" : fouling of the artificial seaweed by the natural variety where it is
present T It showed no measurable effect of the seaweed on seasonal erosion
losses, and burial of the fronds within a few months due to anchor-induced scour
around their base.
In vitro experiments have not been encouraging : at Wallingford (U.K.) onshore
transport was retarded by artificial seaweed and the U.S. Army Corps of
Engineers, at Fort Belvoir VA, found 12% wave height attenuation for short
period waves only which account for only a minor part of ocean energy.
Commercial brands of artificial seaweed include Seascape, Linear Composites,
Sea Leaves and Sea Grid. The Ruhr Universit~it (Bochum, Fed. Rep. Germany)
developed the IMRA system in 1981.
Conclusions reached for artificial reefs cannot be necessarily extrapolated for
natural seaweed formations : these have in their stalks gas filled floatation
nodules that make them more buoyant and have much longer fronds. Natural
seaweeds do retard water motion and move more as compared to wave oscillation
making them more effective.
Besides artificial and natural reefs schemes, proposals have also been made to
place structures or "sparks" to promote aquaculture or myticulture. These
arrangements can play a simultaneous role in coastal protection.
Marsh grasses have been effectively used to control erosion along estuarine
shorelines. At sites with relatively low wave activity, marsh and low cost
breakwater can offer protection at significantly lower cost than several erosion
control alternatives. Rogers based his conclusion on over 25 years of
observations. [M. Rogers Jr, 1989, Erosion Control : marsh and low cost
breakwaters : Coastal Zone '89, I, 781-764]. Successes are numerous but failures
have also been common.
Success has been attained along shorelines that have fringed marshes but were
denuded (viz. stripped).
The recolonization by planting appropriately can re-establish a marsh in two or
three years, rather than decades.