Author(s): Sohaib Baig; Takahiro Sayama; Kaoru Takara
Linked Author(s):
Keywords: Glacier cover; Karakoram; Indus river; Climate change
Abstract: The upper catchments of the Indus river basin host large glacier masses which are projected to decrease due to temperature increase in future. This study focuses on Gilgit river basin (12745 km2) to quantify the change in glacier contribution in case of receding glacier cover. Total glacier area is 1684 km2 (14% basin area) and minimum elevation of glaciers is 3000 m. Four climate stations are installed and average precipitation is 240 mm / year and temperature range is -7 ◦C to 30 ◦C. For hydrological modeling, a runoff routing model with snow and glacier melt models is used. The method is simple and requires less calibration effort and flexible to accommodate various data patterns. The calibration is performed for eight years from 2000 to 2007 with Nash-Sutcliffe coefficient 0.74. Validation is done for 2008-2010 and Nash-Sutcliffe coefficient is 0.70. The streamflow is melt water dominated. Glacier contributes 60% to the streamflow annually, the contribution starts in May and lasts till October. In July, August and September the glacier contribution is greater than snow melt and rainfall runoff. To assess the decrease in glacier contribution four scenarios have been selected i.e. no glacier till 3500 meters, 4000 meters, 4500 meters and 5000 meters. In first scenario the contribution reduced by a meager 0.02% because till 3500 meters 7.8 km 2 glacier cover exists, in second scenario 2.2% of glacier cover is lost and the flow reduced by 5%, in third scenario the flow contribution drops by 20% as a result of 8.7% loss in glacier mass and in fourth scenario 73% of total glacier mass is lost and its contribution drops by 98%.The reduced streamflow will make water management more complex and demand integrated efforts.
Year: 2020