Estimation of sediment delivery ratio at sub-watershed level using revised and modified USLE

Abstract

The success of planning for watershed developmental activities depends on the quality and quantity of information available of natural resources. The process of assessing soil erosion using conventional methods is cumbersome, time-consuming and costly therefore, in the present study, an attempt has been made to estimate sediment delivery ratio at sub-watershed level using RUSLE and SWAT Model. The raster layers of K, L, S, C, P factors and computed R factor value was used to derive gross soil erosion map of study area using raster calculator of spatial analyst tools in ArcGIS interface. The MUSLE was used to route and estimate the sediment yield at watershed outlet using SWAT model. Highest area covered by agricultural land (i. e. 41.54) of study area having 33.28 tons/ha/yr gross soil erosion needs immediate treatment of soil conservation in order to reduce water erosion. The average gross soil erosion rate for study area was estimated as 39.25 tons/ha/yr whereas, the sediment yield by SWAT was estimated to be 22.78 tons/ha./year. The estimated sediment delivery ratio indicates that 58 per cent of eroded soils go out of the watershed which reduces the soil depth and fertility of land on site and reaches Karjan reservoir thus reducing the water storage capacity of reservoir each year.