RESERVOIR SEDIMENTATION STUDIES USING MATHEMATICAL MODELLING

Abstract

Modelling is an important tool for solving river engineering problems. Mathematical modelling of alluvial rivers is done for understanding the behaviour of rivers and also for prediction of its response when subjected to some kind of variation in its controlling parameters. These models invariably incorporate the solution of a set of equations, viz., equation of motion, continuity equation for water and continuity equation for sediment alongwith suitable resistance and sediment transport relations. A number of mathematical models related to morphological changes in rivers have been developed in the past few years. In the present study an attempt has been made to study the applicability of FCM (Fully Coupled Mobile Boundary Model) developed by Correia to the problem of sedimentation in Indian reservoirs. This model in its present form is a one-dimensional, unsteady and fully coupled model. The basic feature of the model is the flexibility in choosing the resistance and sediment transport relationships and taking variable bed roughness into account. The FCM model has been applied to three Indian reservoirs namely, Gobindsagar, Matatila and Nizamsagar. Qualitative agreement between computed and observed depositional profiles was noticed particularly in case of Matatila and Gobindsagar reservoirs. Also the model has been successful in producing the forward movement of deposition front with the passage of time. However, many difficulties which were encountered while using, the model were analysed and listed herein. Also the conditions are identified with regards to the values of parameters, for which the model is found to have numerical stability.