Hydrology of Spillway Design: Large Structures–Adequate Data

The basic factors to be considered in derivation of conservative spillway design floods are examined. A possible classification of dams is presented with three categories of hazard conditions and associated spillway hydrologic design criteria. Procedures are included that permit an evaluation of the effect of impoundment depth on the peak discharge and the effect of impoundment volume on the transmission downstream of the artificial flood that would result from sudden failure of a dam. A brief review is presented of the considerations involved and the hydrologic procedures used in derivation of a spillway design flood for a large dam. Estimation of design storm rainfall and snowmelt, runoff determinations, hydrograph development, and flow routing through the reservoir are investigated.