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Sarfaraz Ahmad ¹, Syed Iqbal Hasnain ¹

Affiliations
1 School of Environmental Sciences, Jawaharlal Nehru University, New Delhi- 110 067, IN

Abstract

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.

Keywords

Glacier Meltwater, Hydrochemistry, Geological Controls.

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Sarfaraz Ahmad ¹, Syed Iqbal Hasnain ²

Affiliations
1 Department of Geology, Aligarh Muslim University, Aligarh - 202 002, IN
2 School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067, IN

Abstract

Mineralogical composition of soil and sediments reveals a decreasing trend of chemical weathering intensily with elevations due to decreasing temperature and short period sf soil solution rcsidence at high altitude soil profiles. Lower values of CIA (lndex of Chemical Alteration) for the soil, suspended and bed sediment also indicates low intensity of chemical weathering and these mineralogical and chemically immature sediments play an important roled in fertility of the flood plains of Ganga - Indus - Brahmaputra system.

Keywords

Texture, Mineralogy, Himalaya, Alpine, Alpine-Subalpine, Sub-Alpine forest stream, Garhwal Himalaya.

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Sarfaraz Ahmad ¹, Syed I. Hasnain ¹

Affiliations
1 Glacier Research Group, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi-110067, IN

Abstract

Water quality of meltwater streams in the Higher Himalaya is mainly controlled by precipitation (snowmelt, icemelt and monsoon rainfall), geology and land use patterns in the region. In response to increase in population growth and acidification of the Asian atmosphere, the quality of stream water in one of the pristine environments of the world viz. the Himalaya has been affected. The quality of water in these streams of the glacier region is controlled by mixing of the surface and subsurface waters. Hence, hydrographic study was carried out to quantify the proportion of glacier meltwater in the two different types of water sources in the stream viz. surface and subsurface. The hydrograph was separated into surface and subsurface component sources using a mixing model, and the electrical conductivity (EC) was used as a tracer for mixing of the surface and subsurface component. The results show that high variability in the temporal variation in the surface and subsurface component of water source in the stream. Average subsurface water contribution to stream water was 37 % of the total runoff. The subsurface water was rapidly flushed out from the system during the initial stages of snowmelting. During the rising limb, surface and subsurface flows contribute about 5 1 % and 48% of the total runoff respectively. Surface water was estimated to be the dominant component of streamflow on the falling limb of the hydrograph and constitutes about 77% of total flow. It constitutes however about 64% of total runoff for the whole water year.

Keywords

Glacial Stream, Meltwater, Hydrographic Study, Garhwal Himalaya.

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