Analysis of unusual meteorological conditions responsible for flash flood occurred in Bhagirathi basin during 2013

Abstract

The Bhagirathi River that originates from the snout of Gangotri glacier at an elevation of about 4000 m is traditionally considered as the source of Ganga River. In June 2013, a multi-day cloudburst centered on the North Indian state of Uttarakhand caused devastating floods and landslides which resulted unmassive loss of lives and property. This unusual rain event occurred during the tourist season in June, consequently trapping a large number of tourists and vendors in this area. Sudden release of stored water generated floods that created havoc downstream of the most of the rivers in this area. This paper presents description of meteorological conditions which led to catastrophic hydrological situation and flash flood as experienced in the large part of Bhagirathi basin in June 2013. The hydro & meteorological and discharge data for 14 June 2013 to 18 June 2013 collected at an observatory near the snout of the Gangotri glacier has been analyzed. This area normally receives less rainfall and the maximum monthly rainfall of the month for June during previous years hardly exceeded100 mm, while total rainfall during this 5-day storm was 178 mm. Sudden increase of water discharge in the river resulted in flooding downstream. Flows at the gauging site peaked at 163 m3 /s on 16th June 2013. It is observed that the mean runoff depths of June varied between 12-14 mm whereas runoff depths recorded up to the site was highest on 16th June 2013.