Migration of a dredging pit in the Rhone River

摘要

Extraction of sediments in a riverbed is currently operated to regulate its profile equilibrium. The excavation pit is submitted to a migration process characterized by successive convection and diffusion phases. This phenomenon has been investigated in a case study of gravel exploitation on the Rhone River in Switzerland. A first approach was conducted on a physical model in order to quantify the impact of the main geometrical parameters of the pit, particularly its length, width and depth. The experimental results have then been used for the development and calibration of a numerical model simulating transient flow on a non-cohesive mobile bed. Numerical simulations allowed proceeding to a sensitivity analysis of the pit migration related to its depth, length and width as well as to the riverbed material gradation. The results highlight the erosion processes which develop upstream and downstream of the excavation zone.