7. Scour Around Marine Structures
217
,Vent of which the time taken to simulate the local scour as per a model
aw will not require considérable time. Particular or unusual cases can also
je model tested as needed.
Information on local scour is well known for the following features:
, bridge piers (of various shapes)
» bridge abutments and other similar structures
» river training works and linear revetments
i spur dikes (groynes) and other banks at various angles to the flow
direction
» weirs and sills
» closures of cofferdams and diversion works.
In some cases, the extent, shape and surface gradients within the scour
hole can also be predicted. The factors affecting the local scour is shown in
Fig. 7.5.
Fig. 7.5 Factors affecting local scour.
7.4.4
Dégradation scour
h is generally referred to as lowering of bed levels along a river reach. This
is often witnessed when the reach strives to regulate its gradient according