Meltwater Characteristics of Garhwal Himalayan Glaciers

A comparative study of the meltwater chemistry from the Gangotri, Satopanth-Bhagirathi, Dokriani, and Bagni glaciers has been done for the late ablation period in October from 1991 to 1994. This late ablation period is characterized by low atmospheric input and lean flow in the glacier streams due to less availability of solar energy for supraglacial melting. During this period subglacial melting has played a dominant role in determining the water chemistry of glacier meltwater. In all studies, the dominant controlling factor on meltwater chemistry has been rock weathering processes, The pH and electrical conductivity of the meltwater from these Himalayan glaciers ranged between 6.9-8.12 and 43-134.8 μS/cm, respectively. The concentration ranges of major cations and anions recorded in the meltwaters of Himalayan glaciers are Ca⁺² (166-800) μeql^-1, Mg⁺² (25.8-344.5) μeql^-1, Na⁺ (11.1 - 124.2) μeql^-1, K⁺ (80-677.6) μeql^-1, HCO₃^- (381-2349.85) μeql^-1, SO₄^2-(192-2234) μeql^-1, and Cl^- (0.72-53.25) μeql^-1. The order of anion concentration in the meltwater is HCO₃^- > SO₄^2- > Cl^-. However, the order of anion concentration in meltwater of Gangotri, Bagni is SO₄^2- > HCO₃^- > Cl^-. The order of cation concentration is Ca⁺² > Mg⁺² > K⁺ > Na⁺ in all studies, except in the Satopanth and Bhagirathi glacier, which showed cation concentration of Ca⁺² > Na⁺ > Mg⁺² > K⁺ type. The purpose of this comparative study is to explain the geological control on the hydrochemistry of the meltwater draining from four different glaciers in the Garhwal Himalaya and to establish the relationship between meltwater hydrochemistry and the basement rock type.