Bed Scour at End-Dump Channel Constrictions

One method of constricting a channel is by end-dumping loose rockfill from one or both banks. This study is concerned with bed scour that occurs around the leading face and downstream of such end-dumped dams built into alluvial channels. Analysis of the problem indicates the Froude number of approach flow, the contraction ratio, and the ratio of the maximum scoured depth to the normal flow depth to be the essential nondimensional variables. The maximum scoured depth is observed to be influenced also by the size and density of the bed sediment. On the basis of laboratory studies, the functional relationship is established and design curves are presented to directly determine the maximum scoured depth. Observations on the location of deepest scour and rate of scour are made.