Evaluating future water security in the upper Yangtze River Basin under a changing environment.

Area of Science:

• Environmental Science
• Hydrology
• Climate Change Research

Background:

• Water security is crucial for social development, ecosystem health, and environmental management.
• The Upper Yangtze River Basin (UYRB) supports over 150 million people and faces escalating water security challenges.
• Increased hydrometeorological extremes and human water use exacerbate risks in a changing environment.

Purpose of the Study:

• To evaluate the spatiotemporal evolution of water security in the UYRB under future climate and socio-economic changes.
• To project future runoff, hydrological drought, and water stress using multiple scenarios.
• To develop and apply a comprehensive risk index (CRI) for assessing future water security.

Main Methods:

• Utilized five Representative Concentration Pathway (RCP) and Shared Socio-economic Pathways (SSP) scenarios.
• Projected future runoff with the Watergap global hydrological model (WGHM).
• Identified hydrological drought using run theory and predicted water withdrawals based on SSPs.
• Developed a Comprehensive Risk Index (CRI) integrating water stress and hydrological drought.

Main Results:

• Future annual average runoff in the UYRB is projected to increase, with more severe hydrological droughts in upper and middle reaches.
• Water stress is expected to rise significantly across all sub-regions, driven by industrial water withdrawals.
• The Comprehensive Risk Index (CRI) indicates more severe water security risks in the middle and far future.
• Tuo River and Fu River identified as hotspots with high water security risks.

Conclusions:

• The UYRB faces escalating comprehensive water security risks in the coming decades.
• Densely populated and economically developed areas like the Tuo and Fu Rivers are particularly vulnerable.
• Urgent adaptive water resource management strategies are needed to address future risks and ensure sustainable development.