Flood Storage in Reservoirs

Flood storage in reservoirs controlled by free‐overflowing, rectangular spillways is investigated by accounting for arbitrary reservoir bathymetry and single‐peaked inflow hydrographs. The general solution of the storage equation depends only on a storage factor. It is found that adequate substitution of the effective hydrograph by a model hydrograph has only a secondary effect on the maximum reservoir outflow when using a proper shape factor. The proposed method allows an immediate application to realistic cases. In particular, the maximum reservoir outflow and the corresponding maximum reservoir level are represented graphically. Of further interest are cases in which the spillway crest length is varied for cost optimization purposes. Computations are explained in detail by examples, one of which includes a comparison of the present solution with the result of the numerically integrated basic equation.