Low flow analysis in Kharun river basin of Chhattisgarh state

Abstract

Drought duration, frequency and severity of low flow of the past events occurred in the Kharun river basin in Chhattisgarh state are analyzed using daily stream flow data. Stream flow drought severity is the total deficit or cumulative deficient runoff volume below the truncation level during the period of the event of low flow condition. The flow volumes at 75% probability are considered as truncation level to obtain deficiency volume and its severity for each event of low flow condition. As the problem of zero flows have been encountered, the probability of ‘zero flow’ and ‘non-zero’ flow values were computed separately and used to estimate joint probability to derive flow duration curves. The river experienced low flow epoch for 23 times over the period of 18 (1989-2007) years period indicating 1 or 2 low flow condition every year. The low flow events in this basin usually begin during July to October and terminate during November to December. The severity of low flow varies from 0.13 to 80.26 MCM and duration of low flow epoch ranges from 13 to 177 days. The maximum severity of 80.26 MCM has been observed for 177 days during September, 2000 to February, 2001.