ASSESSMENT OF WATER BALANCE OF A WATERSHED USING SWAT MODEL FOR WATER RESOURCES MANAGEMENT

An attempt has been made in this study to assess the hydrological behavior of the Kurumali sub basin of Karuvannur river basin using SWAT model and other geospatial technologie s. All the thematic maps and attribute information of the watershed have been collected from various Government agencies. SWAT model has been set up for the Kurumali sub basin by inputting the digital thematic maps, physical properties of soil and climatic parameters. Total area of the watershed corresponding to the outlet chosen at Kurumali is 423 km 2 and its elevation varies from 10 to 650 m. Six different land use and eight soil types were present in the catchment. Calibration and validation of the model have been done by comparing the river flow prediction with the observed values. Nash Sutcliff Efficiency (NSE) and coefficient of determination (R 2 ) has given very high values for the calibration (0.88 and 0.96) and validation (0.90 and 0.99) periods resp ectively. The calibrated model has been used to predict the important hydrologic processes viz. surface runoff, lateral flow, base flow and ET and it was found that base flow amounts to 64 %, lateral flow 12 % and surface runoff 9 % of the annual rainfall. The study has revealed that SWAT model can effectively be used in the simulation of river flow and for predicting the water balance of a river basin in the humid tropic. Water balance information of the basin is of great use in planning water conservation , drainage and flood control