CS(AR)-1/2010 : Monitoring and modelling of the streamflow for the Gangotri glacier

Abstract

The Himalaya is one of the focal regions, both in terms of its cryospheric resources and the dependency of a huge population on rivers originating from this mighty mountain chain. All the major rivers of India, namely, the Indus, the Ganga and the Braharnaputra originate from the Himalayas and receive a substantial amount of melt water from the snow and glaciers. The perennial nature of these rivers and appropriate topographic setting provide excellent conditions for the development of hydropower resources. These rivers have substantial exploitable hydropower potential.

Gangotri Glacier is located in Uttarkashi District, Uttarakhand, India in a region bordering China. This glacier, source of the Ganges, is one of the largest in the Himalayas. The glacier is about 30 kilometres long and 0.2 to 2.5 km wide. Around the glacier are the peaks of the Gangotri Group.The Ganga originates as Bhagirathi from the Gangotri Glaciers. The Bhagirathi is joined by the Alaknanda at Deoprayag and the combined stream is thereafter named as Ganga. It is joined by a large number of tributaries on both the banks in the course of its total run of 2,525 km before its outfall into the Bay of Bengal.

Understanding of glaciers assume importance when difficult scientific and ethical questions need to be answered about sustainable development of mountain ranges and adjoining plains, especially with regard to hydropower, water supply and environmental quality, which has direct bearing on the national growth. In this regard the fluctuation of glaciers, change in runoff, annual balance, sediment transportation and their roles in controlling the climate of the subcontinents are of great significance. The Institute has established permanent discharge monitoring stations near the snout of the glacier. The data set includes rainfall, temperature, humidity, wind speed and direction, sunshine hours, radiation, evaporation, discharge and suspended sediment. The monitoring of Gangotri glacier is intended to be carried for a long period to establish a good data base. The Scientific team visits and carries on investigations for the complete ablation season. In this study the data collected for three years from 2008 to 2010 have analysed and presented.