Glacial runoff and transport of suspended sediment from the Chhota Shigri glacier, Western Himalaya, India

Abstract

Glacial runoff and suspended sediment transport characteristics of the Chhota Shigri glacier were studied during the whole ablation period (May–October 2010). Discharge patterns of this glacier show that August experiences maximum runoff accounting for 34.2 % of the total runoff, followed by July 32.9 %, June 14.3 %, September 12.5 %, May 5.2 % and October 0.9 %. During the study period, the maximum runoff (Qmax) was observed in the evening (4–6 p.m.), whereas minimum runoff (Qmin) was observed in the morning (7–9 a.m.). The lag time between generation of meltwater from the glacier and its emergence as runoff varied from 1 to 4 h depending on the condition of melting during the melt season. A good correlation (r2 = 0.71) was found between daily mean glacierspecific runoff and air temperature of the study area. Daily mean concentrations of suspended sediment for May, June, July, August, September and October were found as 155, 506, 577, 591, 80.9 and 30.8 mg l-1, respectively, showing maximum concentration of suspended sediment in August, followed by July. Suspended sediment load also follows a similar trend. Diurnal variations in the concentration of suspended sediment of the investigation area are directly associated with diurnal variations in meltwater runoff. There is a strong relationship between concentration of suspended sediment and discharge (r2 = 0.79) and suspended sediment load with discharge (r2 = 0.94). The average sediment yield of the Chhota Shigri glacier basin was computed as 1689 t km-2 year-1 during the melt season, much higher than the worldwide and Indian averages.