Computation of Flow Hydrograph of the Highest Rainfall Data by Using Hec- Hms Model in Jhikhu Khola Waterhed Nepal

Abstract

Computer simulation modeling is used as the tool in the present thesis work to model theJhikhu Kholawatershed. The event-base models simulate flood flow and determine volumepeak and time to peak of flood flow generating by any storm event. HEC-HMS model have beenselected to use for simulation. The HEC-HMS requires lumped or conceptual input parameterthat is Unit Hydrograph parameters. Optimization of the parameters has been done to determinethe hydrological parameters that can be used in the Jhikhu Khola and in the ungauged watershedwith similar hydrological and meteorological environment. Optimization was done from the gauged data of the rainfall and runoff with the trail initialvalues for all parameters. Through optimization options available in HEC-HMS different modelparameters have been optimized and Clark’s Unit Hydrograph has been prepared. Theparameters as that of unit hydrograph and base flow have been obtained. This value is used asinput parameters to model the water shed. A hydrograph at the outlet, for eleven selected rainfall,event is obtained from the simulation of the rainfall runoff process by running the model. Thevalidation of the obtained discharge with the observed is also carried out. A regression analysis iscarried out between rainfall and base flow; rainfall and total excess; rainfall and total losses;Rainfall and Direct Runoff;constant rate of infiltration and rainfall, finally a comparison ofobserved, simulated discharge and constant loss of selected rainfall events has been done.