CS(AR)-212 : Development of hydrological drought index based on reservoir level for bargi reservoir

Abstract

A drought index based on reservoir levels has been developed by the analysis of daily stream flow into the Bargi reservoir. The analysis has been carried out considering thirty six years daily flow data with different demand discharge as percentage of mean flow. The actual demand excluding the demands of right bank canal has also been used. 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 high flow years, low flow years and drought years based on the existing reservoir level at actual and different demand discharges. Another drought index is presented, as mean reservoir level minus half of its standard deviation for low flow years and mean reservoir level minus its standard deviation for identification of drought years (moderate and severe drought) respectively.

It was observed that the availability of water was high in relation to the actual demand. In low flow years and even in moderate drought years, the demands from the reservoir could easily be met. It was proposed that the drought index should be developed also by considering the targeted demands of Right Bank Canal.