Evolution of Erosion and Deposition Induced by an Impinging Jet to Manage Sediment

Abstract

Dams are important water infrastructure whose main purposes can be compromised by sedimentation. This causes loss of storage volume, affecting river sediment fluxes and morphology. However, sediment management strategies can be implemented to reduce these impacts. Our goal is to characterize and quantify key processes of an idealized and reduced physical model of water injection dredging, applicable as a sediment management technique. Three sets of experiments were conducted, varying the following parameters: (a) jet discharge; (b) jet angle; (c) bed angle. The spatio-temporal evolution of the main physical processes (scour hole formation, sediment suspension development, and downstream deposition) was analyzed using images of profiles acquired during the experiments. We identified two distinct transport modes depending on how the jet flow connects with the turbidity current, each associated with different stages of scour hole development. In our experiments, the bed-perpendicular component of the exit velocity (momentum) of the jet is the primary driver of the morphological evolution. We demonstrate self-similarity in the longitudinal profiles of the scour hole and downstream deposit. Finally, we discuss practical implications of this study, such as the net displacement of the material, scaling, and limitations. This research contributes to the development of innovative sediment management strategies for water reservoirs and other hydraulic structures.