APPLICATION OF SYSTEMS APPROACH FOR SEDIMENT YIELD ESTIMATION

Abstract

Estimates of sediment yield are needed for studies of reservoir sedimentation, river morphology, soil and water conservation planning, water quality modelling . design of different erosion control structures, etc. The models available in literature for sediment yield estimation are grouped as, (i) Lumped models and (ii) Physically based models. The physically based models are still in state of development, the lumped models make use of empirically derived coefficients in the relations for sediment yield estimations and these are in frequent use in many parts of the world. In the present study, a GIS based lumped method is proposed and validated for prediction of sediment yield and its temporal variation during storm events. Data from three different catchments viz. Karso and Nagwa in Bihar and Kharkari in Rajasthan have been used. The ILWIS-GIS package was used for catchment discrization into grid or cell networks and for evaluation of spatial variation in topographic and land use of the catchment and for presentation of the results obtained. The processes of sediment delivery from cells or grid size areas within the catchment to the catchment's outlet is considered to be represented by the topographic characteristics of the cells. Unit sediment graphs for the catchments are derived by first translating the sediment yield from the cell size areas due to unit value of erositivity index to the catchment outlet and next, routing the same through a linear storage reservoir.