Estimation of rainfall-runoff using curve number: a GIS based development of Sathanur reservoir catchment

A GIS based algorithm has been developed to estimate the rainfall-runoff relationship of Sathanur reservoir catchment based on Soil Conservation Service (SCS) model. The landuse and soil maps were prepared in Arc/Info 9.0 and an arc macro language (AML) programme was developed to assign curve number based on landuse and soil classification including hydrological condition of the area. The algorithm was executed successfully by rainfall data for computation of runoff depth in all the sub watersheds. The study is important for a watershed, which does not have runoff records and can be used for planning of various water conservation measures.