Evaluating Vulnerability of Central Asian Water Resources under Uncertain Climate and Development Conditions: The Case of the Ili-Balkhash Basin

Tesse De Boer,Troy Sternberg,Homero Paltan,Kevin Wheeler

doi:10.3390/w13050615

Abstract

The Ili-Balkhash basin (IBB) is considered a key region for agricultural development and international transport as part of China’s Belt and Road Initiative (BRI). The IBB is exemplary for the combined challenge of climate change and shifts in water supply and demand in transboundary Central Asian closed basins. To quantify future vulnerability of the IBB to these changes, we employ a scenario-neutral bottom-up approach with a coupled hydrological-water resource modelling set-up on the RiverWare modelling platform. This study focuses on reliability of environmental flows under historical hydro-climatic variability, future hydro-climatic change and upstream water demand development. The results suggest that the IBB is historically vulnerable to environmental shortages, and any increase in water consumption will increase frequency and intensity of shortages. Increases in precipitation and temperature improve reliability of flows downstream, along with water demand reductions upstream and downstream. Of the demand scenarios assessed, extensive water saving is most robust to climate change. However, the results emphasize the competition for water resources among up- and downstream users and between sectors in the lower Ili, underlining the importance of transboundary water management to mitigate cross-border impacts. The modelling tool and outcomes may aid decision-making under the uncertain future in the basin.

Highlights

Transboundary closed or endorheic river and lake systems are among the most vulnerable to changes in demand and supply, exemplified by the drastic reduction in surface area and volume of the Aral Sea, Lake Urmia and Lake Chad in the last decades [1]
Using the RiverWare water resource modelling tool, we explore the outcomes for downstream water security using six upstream water consumption scenarios combined with two sets of river runoff simulations, representing historical and potential climate change conditions
The results show the sensitivity of the basin to the combination of stressors: (i) land use change and historical hydro-climatic variability, (ii) potential future climate change under current water demand, and (iii) the combination of land use development and future hydro-climatic changes for the period of 2020–2060

Summary

Introduction

Transboundary closed or endorheic river and lake systems are among the most vulnerable to changes in demand and supply, exemplified by the drastic reduction in surface area and volume of the Aral Sea, Lake Urmia and Lake Chad in the last decades [1]. The closed basins of Central Asia are vulnerable; climate change threatens water supply from glacier systems and increases evaporative losses, while demand is rising [2,3]. The endorheic transboundary Ili-Balkhash Basin (IBB) illustrates these challenges. The Ili River supplies 70–80% of annual inflows to Lake Balkhash, currently the largest endorheic freshwater lake (average volume 106 billion cubic metres (BCM) in Central Asia since the desiccation of the Aral Sea [5,6,7]. In the dry continental Central Asian region, the Ili is an important source of water for the growing cities, irrigated agriculture, energy industries and the RAMSAR protected wetlands in the Ili

Methods

Results

Conclusion