CS(AR)-27/98-99 : Sediment yield estimation for lower Satluj basin

Abstract

The sediment load (tonnes/year) or yield of sediment (tonnes!km2/year) in suspension and as bed load of sand and gravel through river channels reflects upland erosion within the drainage basin and change in storage of sediment in alluvial bottomlands. Much of the sediment eroded from upland areas is deposited (stored) on lower hill slopes, in bottomlands, lakes and reservoirs. Estimates of erosion are considered essential for land and water management, including sediment transport and storage in lowlands, reservoirs, estuaries, and irrigation and hydropower systems. Generally, suspended sediment loads are estimated using an empirical relationship between suspended sediment load and discharge. The relation is usually defined as a power function and is referred to as a suspended sediment rating curve.

the present study relationship between suspended sediment load and discharge has been developed for three basins namely at Kasol. Suni and lower part of the Satluj basin comprising of the portion covered in between Kasol and Suni. The relationship is represented by the power law. Daily suspended sediment and runoff data collected from Bhakra Beas Management Board (BBMB), for the period from 1991-1996 were used. Sediment yield was also estimated for the basin covered in between Kasol and Suni using empirically developed relationship. For estimation of the sediment using these relationships, various parameters such as geomorphological, landuse, topoghraphical etc. were generated using Geographic Information System (GIS) technique. GIS, a technology designed to store, manipulate, and display spatial and non spatial data, has become an important tool in the spatial analysis of factors such as topography, soil, land use/land cover etc. GIS provides a digital representation of the catchment which can be used in hydrologic modelling. The sediment yield was estimated for 3 years and on the basis of these results a factor and the results were compared with the observed data. There is good match between computed and observed sediment data for this basin.