FLOOD ESTIMATION AND FORECASTING 4 STUDIES FOR TEHRI DAM

Abstract

The study has been taken up with the broad objective to develop an operational flood forecasting system for Tehri dam in the long run. In the present study, the spot locations for 15 hydro-meteorological stations have been finalized after undertaking field visits of the entire catchment area. Also a flood estimation model based on geomorpho climatic instantaneous unit hydrograph has been developed for the streams; which are directly contributing in the Tehri reservoir, using this model, Sept. 2010 flood, one of the severe most floods in the recent past, has been estimated. The synthetic unit hydrograph developed by CWC has also been used for I cross verification. The combined discharge of all the 17 streams which are directly going the reservoir works out be 1381 cumecs and 1264 cumecs using Gc1Ul-1 approach and CWC method respectively. The total discharge entering into Tehri reservoir works out to be 3725 cumecs against 2813 cumecs, as per present practice adopted by THDC India Ltd while 3510 cumecs by spillway data.. The developed methodsbased on GcIUH is recommended to be followed for computation of discharge contributed by the small streams directly entering into the reservoir.