Analysis of unusual meteorological conditions that led to recent floods in Bhagirathi basin (Uttarakhand Himalayas)

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 centred on the North Indian state of Uttarakhand caused devastating floods and landslides which resulted in massive 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 most of the rivers in this area. This paper presents a description of the meteorological conditions which led to the 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 14–18 June 2013 collected at an observatory near the snout of the Gangotri Glacier are analysed. This area normally receives less rainfall; the maximum monthly rainfall for June in previous years hardly exceeded 93 mm, while the total rainfall during this 5- day storm was 178 mm. A sudden increase of water discharge in the river resulted in flooding downstream. Flows at the gauging site peaked at 163 m3 s-1 on 16 June 2013. The mean runoff depths for June varied between 12 and 14 mm, whereas runoff depths recorded up to the study site were much higher, being highest on 16 June 2013.