IV. Retreating Shorelines
213
2.1.5
Wave-Return Walls
In cases of flood protection wave-return walls were constructed for example in
Great Britain (Ilfracombe, Teignmouth,..) and Zeeland (Flushing). This drastic
solution only cf.ms adequate if the sea-ward limits of the coastal barrier cannot be
changed any further.
2.1.6
Gabions And Mattresses
Attempts have been made to counteract beach erosion, or to encourage accretion,
by using flexible concrete mattresses, or by synthetic seaweed grids (Netherlands)
(cf. 2.25). Gabions offer a related approach.
GI~OUND WAI' F.&
9~.F~?A6F_
~r~t g0uc
Fig. 25 : Scour of bulkheads and seawalls
They are rectangular shaped metallic cages filled with varied sizes pebbles;
spread out one gabion type resembles a mattress is, usually one half meter (1.64
ft) high and as long as 8 m (26.25 ft) with mesh from 8 to 12 cm (3.2 to 4.8 in)
usually. The mattress is laid upon a slope of appropriate gradient. However, the
materials must be present in situ and one has to cope with corrosion. Gabions can
be used for revetments. Rocks filling the gabions must be at least 10 cm (4 in) in
diameter lest they slip through the mesh.
213
2.1.5
Wave-Return Walls
In cases of flood protection wave-return walls were constructed for example in
Great Britain (Ilfracombe, Teignmouth,..) and Zeeland (Flushing). This drastic
solution only cf.ms adequate if the sea-ward limits of the coastal barrier cannot be
changed any further.
2.1.6
Gabions And Mattresses
Attempts have been made to counteract beach erosion, or to encourage accretion,
by using flexible concrete mattresses, or by synthetic seaweed grids (Netherlands)
(cf. 2.25). Gabions offer a related approach.
GI~OUND WAI' F.&
9~.F~?A6F_
~r~t g0uc
Fig. 25 : Scour of bulkheads and seawalls
They are rectangular shaped metallic cages filled with varied sizes pebbles;
spread out one gabion type resembles a mattress is, usually one half meter (1.64
ft) high and as long as 8 m (26.25 ft) with mesh from 8 to 12 cm (3.2 to 4.8 in)
usually. The mattress is laid upon a slope of appropriate gradient. However, the
materials must be present in situ and one has to cope with corrosion. Gabions can
be used for revetments. Rocks filling the gabions must be at least 10 cm (4 in) in
diameter lest they slip through the mesh.