EFEECTS OF ORIENTATION ANGLE ON RIVER-BED FORMATION USING SUBMERGED SPUR-DIKE GROUPS

Abstract

Continuous spur dikes were often used to create diverse river-bed forms. We investigated the effects of the orientation angle of spur dikes on the flow structure and bed formation. Three submerged spur dikes were included in a group structure and they were set on both sidewalls alternately. The velocity distributions were measured and calculated by using a simple 3-D numerical model. Calculated results show a fairly good agreement with the experimental data. The overflow on spur dikes was deflected to the direction normal to the spur-dike line. In upstream-oriented spur-dike groups, large scour holes were observed in front-edge regions of spur dikes and deposition regions were formed beside the sidewalls. In downstream-oriented spur-dike groups, front regions of spur dikes and sidewall regions were largely scoured. These bed forms were created by characteristic 3-D flow structures around submerged spur dikes.