FLOW AND BED TOPOGRAPHY AROUND IMPERMEABLE SPUR DYKES

Abstract

Laboratory experiments were carried out in a straight channel with movable bed in order to study bed deformation around spur dykes. The channel has an asymmetric compound cross section, whose flood plain is partially removed and impermeable spur dykes are set, in which 10 successive rectangular embayments are enclosed. Water surface profile and bed level change were firstly measured, then velocity measurements were conducted after fixing the bed geometry. Interaction between flow patterns and bed deformations are discussed. The maximum scouring depth appearing in the vicinity of dykes are evaluated by adopting an empirical equation for a cylinder. Sediment volumes from/into one embayment are calculated from the measured results. A necessary number of embayments effective in showing good deposition area in one group is indicated from these results.