TR-106 : Hydrological investigations on Chhota Shigri Glacier (HP)

Abstract

There area a number of glaciers which cover significant zones of the mountains. The glacial melt contributes to the flow in rivers rising in the Himalayas especially during April to September. For a better understanding of the physics of glaciers and for estimation of glacier melt, hydrological investigations have been carried out in Chhota Shigri Glacier in Himachal Pradesh over a period of 3 years ( 1986-88). The discharge measurements in the melt stream have been conducted by velocity-area method and salt dilution technique. The coefficient between average velocity and surface velocity of flow is determined by observations taken by current meter. The average value of discharge has been observed about 10 cumecs in the month of July and August. However, it reduced to 1 cumec in the beginning of September.

A complete hydrograph is obtained making hourly observations of discharge for 48 hours. A comparison of diurnal variation in discharge with recording of temperature at the glacier surface helped to determine the time lag in melting of glacier and observation at the gauging site. A time lag between 1-3 hours was observed for this glacier. It has been found that time lag depends upon the accumulation area, ablation area and drainage pattern of the glacier. A water level recorder was installed to record the fluctuation in water level of the melt stream.

Snow density and temperature profile of the snowpack and firn over the glacier have been measured in the accumulation and ablation zones during expedition in 1987 and 1988. The magnitude of suspended sediment transport in the glacier melt has also been made by scooping a certain volume of water and sediment mixture at the discharge measurement site.