RN-26 : Sedimentation in reservoirs

Abstract

Sedimentation is a natural process which occurs whenever the flow of a sediment carrying river is impounded by any kind of obstacle. Proper management of water resources often requires the construction of dams, in order to control the irregularity of river discharges. Hence, sedimentation is inevitable whenever a dam is constructed. As a consequence of this, a part of reservoir becomes gradually filled up with sediment deposits, causing a significant reduction in storage capacity. This makes the process of reservoir sedimentation very important and crucial.

The present report attempts to review the process of reservoir sedimentation. The importance of reservoir sedimentation has been highlighted. The various processes contributing to reservoir sedimentation like aggradation, degradation, sources of sediments etc. have been discussed. A mention of useful basic concepts of hydraulics which are important for reservoir sedimentation has been made. Properties of sediments have been described as they would control the reservoir sedimentation in big way. Various empirical, analytical/mathematical and experimental procedures for the prediction of reservoir sedimentation have been described. Impacts of reservoir sedimentation and methods to control reservoir sedimentation have been brought out. The procedures of field surveys and results for various Indian reservoirs have been given.

The report also brings out the various knowledge gaps in respect of understanding the physical phenomena of reservoir sedimentation, including physics of sedimentation, quality of deposits etc, lacuna in measurement techniques, surveying techniques, prediction methods. The report also stresses the need for mathematical modelling to predict the reservoir sedimentation.