FLOOD FORECASTING USING GEOMORPHOLOGICAL INSTANTANEOUS UNIT HYDROGRAPH

Abstract

Unit Hydrograph method is a simple and versatile technique used for the computation and forecasting of flood hydrograph. Rodriguez-Iturbe and Valdes introduced the concept of Geomorphological Instantaneous Unit Hydrograph (GIUH) in 1979. In the present study, the GIUH has been used for flood forecasting. The complete; shape of GIUH is obtained by linking its peak discharge (q ) and time to peak (t ) parameters with the p a Nash model parameters 'n' and "k'. The on line computation of rainfall excess has been made using SCS method. Finally, for checking the validity of this methodology it has been applied to six flood events of Kolar river basin. The performance of flood forecasting based on GIUH was compared with other existing unit hydrograph based modelssuch as Nash model, Clark's model and synthetic unit hydrograph. The results,for forecasting of peak discharge, and time to peak are quite satisfactory. However, there is a need for testing the above methodology on a wide variety of gauged basins before arriving at definite conclusions.