3.3-Short term glacio-hydrological relationships and their effect on the water balance in a glacierised basin

Abstract

The results of glaciological studies carried out during 1988 expedition to Chhota Shigri glacier basin have been discussed. The analysis of hourly temperature data collected at 3 different locations in the valley indicates that the environmental lapse rate in the basin remained in the pseudo adiabatic range i.e. 0.38 oC/100m to 0. 67 oC/100m during the observation period. This could be attributed to high values of relative humidity (70-957.) recorded during this period. The phenomenon of temperature inversion was also observed during early morning hours just after the sunrise and negative values of temperature lapse rate (as low as -1. 1oC/100m) were recorded. The study of energy balance over the glacier surface during this period reveals that of all the energy fluxes, insolation was the largest contributor to the energy budget. Temperature was found to be the most meaningful surrogate variable of energy exchange process over the glacier surface. The degree day factor for Chhota Shiciri glacier was worked out to be S.2 mm/oC for the ablation season and threshold temperature was estimated to be -1. 9oC. The studies with regard to the water balance for the basin during the ablation period show that groundwater contribution is maximum to the total runoff and it s share varies from on an average 56.2% on rainy days. The contribution due to surfacial melting on glacier surface to the daily runoff varies from 9. 8% to 57. 1% depending upon the meteorological conditions.