Hydrogeochemistry of the Upper Ganges River, India

Analyses of more than fifty water samples were conducted to evaluate the chemistry of the Upper Ganges River system. Major ion concentrations were measured for the Alaknanda, Bhagirathi and the Upper Ganges River. High velocity water of the livers may lead to excessive mass transport over the rock weathering. Mechanical weathering plays a major role at the sources of the tributaries, where alpine glacial environment persists. However, chemical weathering is a major factor in determining river water chemistry in downstream temperate areas. Results indicate Alaknanda has more alkalinity and hardness as compared to the Bhagirathi. Rocks of Sub-and Lesser Himalayas have greater influence on total water chemistry, compared to Precambrian rocks of the Higher Himalayas. Rocks of the Higher Himalaya are major source of sodium and potassium ions in the river water, whereas Sub-and Lesser Himalayan rocks are major contributors of calcium, magnesium and sulphate ions. Na/Na + Ca ratio and ranges of TDS for the river system suggest that chemistry of Upper Ganges River and its tributaries is dominated by rock weathering processes.