Prediction of daily reservoir inflow using atmospheric predictors

Reservoir systems need the forecast of rainfall and inflow on daily time scale for planning of water allocation to different users. Prediction of daily rainfall or daily reservoir inflow is a challenging task in water resource management. This study aims at forecasting the daily reservoir inflow using the projections of atmospheric variables extracted from the global climatic models as input. Daily rainfall series for the future period is simulated using a calibrated weather generator based on generalized linear models. The simulated daily rainfall series are compared with the monthly predictions obtained from local polynomial regression model, and the best correlated daily rainfall simulation is transformed into stream flow using a calibrated and validated soil and water assessment tool to generate the daily inflow series. The modelling procedure was applied to a typical reservoir catchment in India. Diagnostic checks carried out to assess the performance of the rainfall simulations revealed that the simulated series are having the same statistical characteristics as that of the observed series. The simulated inflow was found to be acceptable with respect to the performance indicators evaluated in the study. The methodology adopted is data driven, flexible and easy to implement.