Simulation of Reservoir Inflow Using HEC-HMS

Abstract

Reservoir inflow plays a key role in hydrological predictions such as drought and flood predictions as well as in reservoir operations, and thus precise prediction of reservoir inflow is of utmost importance. As reservoir inflow pattern predominantly depends upon the rainfall-runoff process, land use and land cover pattern and climate change within a catchment area, accurate prediction of it, is a difficult task. Koyna dam reservoir is one of the major reservoirs in India which serves the multipurpose functions including hydroelectric power generation and thus for efficient reservoir operation; accurate inflow prediction is the need of the day. Consequently, present study aims in predicting the Koyna reservoir inflow using—a conceptual model, Hydrologic Engineering Centre’s Hydrologic Modelling System (HEC-HMS; version 4.8). The Soil Conservation Service Curve Number (SCS-CN), SCS unit hydrograph, and time interval were selected for each component of the inbuilt processes of loss method, transform method, and channel routing, respectively, while developing the HEC-HMS model. To evaluate the model performance, relative error (%), root mean square error (RMSE), correlation coefficient (r), and Nash–Sutcliffe efficiency (CE-NSE) are used along with simulated and observed hydrographs and scatter plots. From all the results, it can be said that the overall performance of the HEC-HMS model is reasonable and trustworthy and can be applied in similar area of research interest.