Spatial sedimentation characteristics in shallow trapezoidal reservoirs

Abstract

In this study, a related and hitherto largely unexplored and unreported area of sedimentation in trapezoidal reservoirs is investigated, with the aid of a coupled numerical hydrodynamic and sediment transport simulation model. This research study is categorised into the following steps: identifying significant geometric parameters defining any typical storage reservoir, setting up and running a numerical model for simulating flow and sediment movement for a range of possible geometries, expressing characteristic parameters defining the extent of sedimentation (height of sediment mound, spatial spread and longitudinal extent) in terms of the geometric parameters, validating relations so obtained with field observations of sedimentation from the Hirakud Reservoir (Eastern India) within its two contributing rivers — Mahanadi and Ib. The study shows that the reservoir geometry and bathymetry significantly influence the flow field which, in turn, dictates the conditions of sediment transport and deposition within the reservoir. The developed relations are expected to help the reservoir managers in understanding the nature of bed elevation rise with time for a given reservoir and for planning desiltation strategies for conserving reservoir capacity.