Regression models for within-year capacity adjustment in reservoir planning

Streamflow data from 12 international rivers were used to develop predictive relationships for total (i.e. within-year plus over-year) reservoir capacity as well as the within-year capacity adjustment for use during reservoir planning. The models were then validated using data from three other international rivers. In general, it was found that the performance, during both calibration and validation, of the combined capacity model was better than that of the within-year capacity adjustment model. The two models are applicable only if an estimate of the over-year capacity is available. Methods of independently estimating the over-year capacity, as well as the other derived factors used as independent variables in the regression models, are described for gauged and ungauged sites.