TEMPORAL VARIATION OF LOCAL SCOUR

Abstract

TEMPORAL VARIATION'OF LOCAL SCOUR The knowledge of the maximum scour depth during heavy floods is essential for a proper design of foundation of hydraulic structures like bridge piers, abutments, guide bankS etc. The flow during a flood is unsteady and discharge changes are quite rapid. - But the existing methods for calculating the maximum scour depth consider only. steady flow. Analysis of scour due to unsteady flow is possible if the temporal variation of scour in steady flows is first under8tQOd, Therefore it was thought desirable to establish a relationship for the time variation of scour depth. For this purpose the available data on the problem have been analysed. As a result of this, relation have been proposed for evaluating the time-variation of scour depth. A scheme has been developed for computing, the scour depth when discharge increases with time. The scheme has been tested using hypothetical data