Small-scale laboratory dam-break waves on movable beds

Abstract

This paper documents a series of small-scale laboratory experiments of dam-break waves propagating over loose granular beds, realised in a dedicated flume equipped with a fast downward-moving gate. The flood wave generates intense geomorphic action as bed sediments are eroded and entrained by the flow. Two distinct bed materials, sand and Polyvinyl Chloride (PVC), and a range of initial bed configurations are explored. The sediment bed is either flat or features an upward or downward discontinuity of level across the gate. The case of an initial non-zero water depth downstream is also investigated. The flow is imaged through the sidewalls with fast digital cameras. Imaging techniques are used to identify characteristic flow regions and to derive full velocity fields by tracking the movements of individual bed sediments as well as neutrally-buoyant tracers. The data set described in the paper is provided in digital form in the electronic supplement to this special issue.