CLEAR-WATER SCOUR AROUND ABUTMENTS IN FLOODPLAINS

Clear-water scour around a bridge abutment in the floodplain of a comp ound channel was investigated. Experiments were conducted in a flume w ith a fixed-bed main channel and a movable-bed floodplain in which the abutment terminated. Flow depth, discharge, compound-channel geometry , and abutment length were varied, and measurements of approach veloci ty distribution and scour depth were obtained. A preliminary relations hip for the dimensionless scour depth is suggested to illustrate the c ompound-channel effects on scour. The proposed relationship is limited to the range of values covered by the variables in this study.