Evaluating the sensitivity of glacier rivers to climate change based on hydrograph separation of discharge

The magnitude and variability of water system's response to climate change impacts have been assessed through a detailed analysis of discharge composition of two selected typical glacier rivers originated from Tianshan Mountains, Xinjiang Uygur Autonomous Region in West China, which is considered as the water tower of Central Asia. Here we demonstrate climate change in the last 60 years using meteorological data (1951-2009) in the region. Both of the temperature and precipitation show a remarkable rise before and after year 1990 and these changes are much more significant in North Xinjiang than it is in South Xinjiang. Response of water systems towards climate change is then assessed by comparing annual discharge change of Urumqi River (10.0%) in the North and Kumalak River (38.7%) in South Xinjiang. We found significant inconsistency of the climate change impact on water resources. Furthermore, we quantitatively determine the ratio of ice-melt water using isotope hydrograph separation as well as other conservative tracers. Results show that Urumqi River is recharged by less than 9% of ice-melt water, while Kumalak River contains more than 57% of ice-melt water in their discharges. The extent of glacier input to a water system governs its sensitivity towards climate change. The method has overwhelming potential for un-gauged watersheds and may offer ways of adaptation to climate change in terms of water resources management for flood control and sustainable agriculture. (C) 2012 Elsevier B.V. All rights reserved.