IV. Retreating Shorelines
221
It has but rarely been suggested to construct artificial islands or reefs to counter
erosion of a shoreline (cf. 2.1.7). Nevertheless the protection role played by a
proposed "environmental" island offshore the Belgian coast has been mentioned
as a side "benefit". This island would be the site of a waste processing plant (R.H.
Charlier and C.P. De Meyer. "An artificial, 'environmental' island offshore the
Belgian coast" Proc. Oceans '87 MTS/IEEE Int. Conf. (Halifax, N.S.) (1987).
New designs for "hard" protective structures suggested include a variety of
groins : stacked bag filled (with sand or grou0, timber crib and timber plank
groins. Longard tubes can be used in groins, breakwaters and bulkheads. Sheet
pile groins and bulkheads - made out of timber, steel or aluminium - are in use,
and gabions can be groins or breakwaters. Sandgrabbers, surgebreakers and Zwalls are patented breakwaters.
2.2
Environmental Aspects
Groins and breakwaters will only affect the wave regime and sediment transport
in the immediate area. They do not provide solutions for the adjacent coastal
areas where the sediment transport capacities are unchanged. To the contrary,
they may cause a spectacular increase in sediment transport on the lee-side of the
structure causing renewed coastal erosion. In fact, the problem has merely been
moved from one area to another.
Although reports have overwhelmingly faulted sea-walls for causing beach
erosion, some authors maintain that in several cases this has not been proven 19.
If recreational aspects are important, any coastal structure (e.g. groin) on the
beach should be avoided. Furthermore, considerable sums of money have to be
repeatedly spent on maintenance and repair due to storm damage to the
structures.
In 'Impact de la Construction de la digue portuaire de Mohammedia sur les
plages avoisinantes" a poster at Bordomer '95, J. Viguier points out that prior to
the construction of the seawall, the beach was in virtual equilibrium with a slight
accretion at the western end and some erosion at the east end. Erosion was in
progress at Monika beach, but it had been 'hained" considerably to build a
"ttevelopment" in 1970, in the central area of the high beach. That development
is threatened by the sea today.
221
It has but rarely been suggested to construct artificial islands or reefs to counter
erosion of a shoreline (cf. 2.1.7). Nevertheless the protection role played by a
proposed "environmental" island offshore the Belgian coast has been mentioned
as a side "benefit". This island would be the site of a waste processing plant (R.H.
Charlier and C.P. De Meyer. "An artificial, 'environmental' island offshore the
Belgian coast" Proc. Oceans '87 MTS/IEEE Int. Conf. (Halifax, N.S.) (1987).
New designs for "hard" protective structures suggested include a variety of
groins : stacked bag filled (with sand or grou0, timber crib and timber plank
groins. Longard tubes can be used in groins, breakwaters and bulkheads. Sheet
pile groins and bulkheads - made out of timber, steel or aluminium - are in use,
and gabions can be groins or breakwaters. Sandgrabbers, surgebreakers and Zwalls are patented breakwaters.
2.2
Environmental Aspects
Groins and breakwaters will only affect the wave regime and sediment transport
in the immediate area. They do not provide solutions for the adjacent coastal
areas where the sediment transport capacities are unchanged. To the contrary,
they may cause a spectacular increase in sediment transport on the lee-side of the
structure causing renewed coastal erosion. In fact, the problem has merely been
moved from one area to another.
Although reports have overwhelmingly faulted sea-walls for causing beach
erosion, some authors maintain that in several cases this has not been proven 19.
If recreational aspects are important, any coastal structure (e.g. groin) on the
beach should be avoided. Furthermore, considerable sums of money have to be
repeatedly spent on maintenance and repair due to storm damage to the
structures.
In 'Impact de la Construction de la digue portuaire de Mohammedia sur les
plages avoisinantes" a poster at Bordomer '95, J. Viguier points out that prior to
the construction of the seawall, the beach was in virtual equilibrium with a slight
accretion at the western end and some erosion at the east end. Erosion was in
progress at Monika beach, but it had been 'hained" considerably to build a
"ttevelopment" in 1970, in the central area of the high beach. That development
is threatened by the sea today.