RAINFALL RUNOFF RELATIONSHIPS OF A NATURAL WATERSHED

Abstract

Stream flow of Yagachi Watershed (552 Sq.km., in area), a subbasin of Hemavathi river in Cauvery basin was simulated with the help of SEAMOD, which is a conceptual simulation model. This model simulates the various hydrologic processes occuring in a watershed at a seasonal time scale. The model is based on determining the water balance in the various storages of the watershed, where some of the input and output variables are determined by parametric relationships. The model Computed Surface Storage, Infiltration Volume, water available for surface runoff. Evapotranspiration loss, Soil Moisture storage, Deep perculation, Ground water storage volume, Base flow and Total stream flow fairly accurate on monthly basis. Stream flow of the watershed was simulated using monthly rainfall, runoff, pan evaporation, for the water years 1970-71 to 1974-75 with relative percent errors as 4.75 % and 13.18% percent for high and low flows respectively. Streamflow was predicted for water years 1975-76 to 1979-80 with relative percent errors 0.06 percent and 10.64 percent for high and low flows respectively.