Three dimensional flow structures were measured by using PIV to clarify the mechanism of sediment deposition caused in a riverside embayment with various shape configurations in a compound open channel. The 3-D flow structures were deformed by the step angle and they were related well to the deposition configuration. The upstream-oriented backward facing step causes the reattachment downward flow and the secondary flow in the center of the riverside embayment zone. Total amount and bed configuration of sand deposition were correlated with the typical 3-D flow structures.
