TR(BR)-136 : Development of hydrological drought index based on reservoir level

Abstract

A drought index based on reservoir levels has been developed by the analysis of daily stream flow into the Malaprabha and Ghataprabha reservoirs, in Belgaum district of Karnataka. Part of the catchment area as well as the command areas of the above reservoirs fall in the classified drought prone area as per the Central Water Commission (CWC) The analysis include the annual flow departure analysis, analysis of maximum drought volume (storage volume), analysis of water available days and mean monthly available storage in terms of reservoir level. The results of the analysis are presented in the form of nomograms for the identification of drought based on the existing reservoir level at different threshold discharge. Another drought index is presented, as mean reservoir level minus half of its standard deviation for mild drought and mean reservoir level minus its standard deviation for identification of moderate drought respectively.