The design conditions for the seawall have to be properly chosen. įigure 2 Seawalls with measures to reduce overtopping the DUROSTA computation model an estimate of expected scour depths can be made. The scour hole might undermine the seawall. (A part of) the 'denied' erosion volume from the mainland, is now eroded just in front of the seawall. Some scour in front of the seawall during a storm (surge) must be taken into account in the design. While in a situation without a seawall even a moderate storm (surge) will attack and erode the mainland, in the situation with a seawall this is prevented. So a normal beach is assumed to be present in front of the seawall (and can be used for recreational purposes). The beaches in front of the seawall do not erode, or in case of a structural eroding coast an essentially (time-averaged) stable situation has been achieved with e.g. Staircases facilitate the access to the beach. At the sea side of the seawall a more or less normal beach is assumed to be present at the land side a road or a boulevard is present. Solving coastal engineering problems Clear transition beach-mainlandĮspecially in sandy coastal areas with a lot of human (recreational) activities, a clear and fixed distinction between beach and mainland is desirable. For some general information on seawalls, see also Seawall. For more information on different types, characteristics and application of revetments, see also the article Revetments. Slightly different definitions are given in the definition pages of seawall and revetment. 1:2 or 1:4), while a seawall is often almost vertical, the surface of a revetment might be either smooth or rough (a seawall is mostly smooth) and that the height of a revetment does not necessarily fill the total height difference between beach and mainland (a seawall often covers the total height difference. The main difference is that it is more sloping than a seawall. The seaward side of the seawall is thought to be rather smooth.Ī revetment is, just as a seawall, a shore parallel structure. In the present article with a seawall an almost vertical structure is meant. At the initial time of construction a seawall is situated close to the position of the dune foot. In many cases adjacent at the crest of a seawall a horizontal stone covered part is present (e.g. The height of a seawall fills often the total height difference between beach and surface level of the mainland. Seawalls or revetments are shore parallel structures at the transition between the low-lying (sandy) beach and the (higher) mainland or dune. 2.3 Existing row of dunes does not meet safety requirements.2.2 Decrease risks of valuable infrastructure and buildings.
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