In the study, Soil Conservation Services Curve Number (SCS-CN) method is used to predict runoff volume from the Bewas basin at a dam site meant to augment municipal drinking water supply to Sagar city. The SCS-CN model involves relationship between land use, land cover, hydrologic soil class, and runoff Curve Number of hydrologic soil cover complex, which in turn is a function of soil type, land cover and antecedent moisture condition.
The ancillary data on land use and land cover was interpreted from IRS IB, LISS II imageries of the catchment area. ArcInfo GIS package has been used to analyze the spatial database. The general relationship between the direct runoff and the rainfall recorded at the four rain gauge stations in the Bewas catchment area were also developed for all the three antecedent moisture conditions (AMC I, AMC II and AMC III).
The discharge measured by the Public Health Engineering Department (PHED), Sagar and the direct runoff volume estimated using SCS-CN method were compared and the monthly correlation coefficient was calculated. In general, good correlation was found between the measured and estimated runoff volumes. The seasonal correlation coefficient varies between 0.92 and 0.94.
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