Complexities in modelling water availability in the water-scarce Aksu catchment, northwest China

The Aksu River, located in an arid region of northwestern China, is a snow and glacier melt-dominated river originating in the Tian Shan mountain range. Over the past 40 years, an increase in river discharge was reported, assumed to be caused by enhanced glacier melt due to a warming climate. Rapid population growth and economic development have led to a significant expansion of irrigation agriculture in the oases along the river, resulting in a decline of river discharge downstream and water shortage for floodplain vegetation. Hence, pressures on water availability for agricultural land has become ever more important in this water-scarce region under a warming climate. Complexities of this unique hydrological system are presented. Additionally, a combined modelling strategy using the ecohydrological model SWIM and the water resource management model WEAP is proposed. The upstream natural river discharge could be simulated by the semi-distributed model SWIM, while the downstream water management in various irrigation areas could be analysed by WEAP. Application of these models for this glacier-fed, arid basin is challenged by data scarcity and significant hydrological engineering modifications during the last decades. Insufficient data on water use adds further uncertainty.