Hydrologic Design of Ramganga Dam Project

Hydrologic design of Ramganga Dam, a major dam in northern India, brings forth the special problems in countries where limited hydrologic data are available. The extension of the stage-discharge curve for the river necessitated backwater computations and development of suitable correlations because of the varying friction slope. Monthly rainfall-runoff relations from limited data have been used for transforming the rainfall data and for preparing a 60-year water budget to determine the useful reservoir yield and its probable variation. Optimum baseflow for use with unit hydrograph and design storms was estimated from the association between the flood-producing storm and the antecedent baseflow. Regional flood potential study was found to be a useful tool for checking design floods derived from design storms and unit hydrograph. Provision of an auxiliary spillway at a safe distance from the main dam reduces reservoir surcharge for extremely rare floods.