Accumulation and flow rates of ice on Chhota Shigri glacier, central Himalaya, using radio-active and stable isotopes

Abstract

Systematic isotopic studies based on natural and artificial radio-isotopes (32Si,137Cs), stable isotopes (δ18O) and total β activity measurements have been carried out on Chhota Shigri glacier, Himachal Pradesh, central Himalaya, to study the dynamics of the ice, meltwater composition and to identify the deposition of the Chernobyl fall-out in the Himalayan region.Using32Si concentrations, the snout ice has been dated at ~ 250 years, based on which the past average surface ice-flow rate has been estimated as ~ 28 m year−1. Based on δ18O variations, in a shallow ice core, the accumulation rate of the ice has been estimated at ~520kgm−2year−1.32Si measurements of snout ice and englacial meltwaters indicate that at least 55% of the snow meltwater mixed with 45% of the old ice-melt water that emerged from englacial streams in the month of August 1987. Deposition of the artificial radionuclide (137Cs) and the very high total β activity observed in snow samples on Chhota Shigri glacier give the first evidence of Chernobyl fall-out deposition in the Indian Himalaya.

Four years of mass balance on Chhota Shigri Glacier, Himachal Pradesh, India, a new benchmark glacier in the western Himalaya

“…The total retreat of the snout between 1963 and 1989 has been evaluated at $195 m (mean retreat over these 26 years of 7.5 m a -1 ; Dobhal and others, 1995), but a recent study (Kulkarni and others, 2007) reports an accelerated retreat since 1988, with an 800 m retreat of the glacier terminus between 1988 and 2003 (mean retreat over these 15 years of 53 m a -1 ). Mass-balance measurements and accumulation estimates were attempted in 1987-89 (Nijampurkar andRao, 1992;Dobhal and others, 1995;Kumar, 1999) but they are questionable because stakes were drilled into the ice only up to 1 m depth and only part of the accumulation area is taken into account in the calculations.…”

Seasonal variation in stable isotope compositions of waters from a Himalayan river: Estimation of glacier melt contribution

“…Time series of (a) δ 18 O and δD; (b) d ‐excess values for the Parbati River water samples; (C) comparison of δ 18 O values of the Parbati River water samples (present study) with some precipitation isotope data taken from nearby high elevation stations (Kumar et al, ). δ 18 O values of meltwater, surface snow, and surface ice from Chhota Shigri glacier along with the variations also presented (Giggenbach, Gonfiantini, & Truesdell, ; Nijampurkar & Rao, ; see text for details of the sampling times in these studies)…”

“…Higher δ‐values during the spring are ascribed to relatively higher contribution from snowmelt. Published data from Chhota Shigri glacier show that snows have generally higher δ 18 O values (~ −7‰) compared with the glacier ice (~ −9‰) and snout melt (−11‰; Nijampurkar & Rao, ). Similar enrichment of snow (−9.9‰) compared with glacier ice (−13.1‰) was observed in case of Gangotri glacier (Lambs, ).…”

“…The isotopic values for the Man‐Talai glacier melt are not available. Therefore, isotopic values of Chhota Shigri glacier (−6.3‰ to −10.9‰ with an average of −9.1‰; Nijampurkar and Rao, ) are adopted here as glacier/snow melt end member (Table ). Mixing of groundwater with δ 18 O value of −10.15‰ and the glacier/snow melts with the δ 18 O value of −9.1‰ at 20:80 proportion yields δ 18 O value of −9.3‰, matching the mean δ 18 O value of the river water observed during MAM period (Figure a, Table ).…”

Socio-economic and environmental implications of the hydroelectric projects in Uttarakhand Himalaya, India

“…The Himalayan glaciers are the summer accumulation type, i.e., maximum accumulation and ablation occurs during the summer monsoon (Nijampurkar andRao 1992, Kulkarni 1992).…”