Causes and geomorphological effects of large debris flows in the lower valley areas of the Meru and Gangotri glaciers, Bhagirathi basin, Garhwal Himalaya (India)

Abstract

ABSTRACTThe present study investigates the debris flow occurred in July 2017 at the terminal moraine of the Meru glacier, Bhagirathi basin, Garhwal Himalaya. This event has changed the geomorphology of the Gangotri glacier’s snout and downstream of the Bhagirathi river due to massive debris displacement. The causes of the debris flow were analyzed using Sentinel-2A and Google Earth (GE) images, gridded precipitation data of the Global Precipitation Climatology Centre (GPCC) and the Tropical Rainfall Measuring Mission (TRMM). The chronological analysis of Sentinel-2A satellite and Google Earth (GE) images show the expansion in the size of the moraine-dammed lake at the terminus of Meru glacier, which later breached and triggered the debris flow. The analysis of rainfall data shows that the area received heavy rainfall during the event, triggering a massive debris flow.