Effect of glaciers on the annual catchment water balance within Budyko framework

Abstract

The effects of catchment characteristics and climate variables on water partitioning into evapotranspiration and runoff can be evaluated using the Budyko framework. However, the influence of glaciers on catchment characteristics within the framework has yet been adequately investigated. Here we extend the Budyko framework and apply the elasticity method to examine the effects of glaciers on runoff between 2001 and 2010 in 25 upstream catchments of the Tarim River Basin in western China. The consideration of glacier mass balance and glacier fraction improves the performance of the Budyko framework, especially for the catchments with a high glacier fraction. We found that the catchment characteristic parameter ω was strongly affected by glacier fraction, and it changes from 1.15 to 2.09 when glacier fraction decreases from 0.4191 to 0.0005. This also reflects the change in water–energy partitioning that eventually effects on evapotranspiration and runoff. We further assessed the average runoff responses to changes in precipitation, potential evapotranspiration, glacier mass balance, and glacier fraction in the 25 catchments. Although the runoff appears most sensitive to precipitation in average, its sensitivity to glacier mass balance and glacier area in fact rises from −0.07% to 0.17% and about 0–0.54%, respectively, when the glacier fraction increases from 0.0005 to 0.4191, further demonstrating the increasing influence of glaciers when the fraction becomes larger. After all, the inclusion of glacier factors in the Budyko framework allows us to understand more about the impacts and contributions of glaciers to runoff at a catchment scale.