Two-Dimensional Depth Averaged Numerical Modelling of Flow Pattern and Sedimentation in Shallow Reservoirs

Shallow reservoirs are hydraulic structures used for stormwater management or for trapping sediments.
Sedimentation in these structures must be minimized or maximized. Sedimentation depends on the flow
structures, which in turn depend on the reservoir geometrical shape and its hydro-sedimentary
characteristics.In this work, the ability of two-dimensional (2D) depth averaged numerical models using
Shallow-Water Equations to simulate flow and sedimentation in shallow reservoirs is examined. Existing
laboratory rectangular reservoirs with different locations of inlet and outlet channels and bottom topography
(i.e. flat bottom, sediment deposits), are simulated.The model is applied on real shallow basin which operates
as a lower basin of a Pumped Storage Hydropower Station.For laboratory cases, a detailed study of the
effects of various user-defined numerical model parameters is performed, including the numerical scheme for
solving the advection step for velocity and turbulence and the turbulence model. Satisfactorymodel-data
agreements are obtained with TELEMAC-2D using the Spalart-Allmaras turbulence model. Simulating the field
case, the hydro-sedimentary numerical model TELEMAC-2D coupled with GAIA has been used to explore
potential enhancements for the management and maintenance of the basin.A scenario with a deflector placed
at the entrance has shown its efficiency in increasing sediment deposits in the northern part of the reservoir
where dredging operations can be conducted easily.