Prediction of the Impact of the Central Yunnan Water Diversion Project on Reducing Water Shortage Risk and Its Inequality in Receiving Areas Using an Integrated Framework

Water resources are essential for human survival and socio-economic development, yet ensuring a reliable supply to meet domestic, industrial, and ecological demands remains a critical challenge in water-scarce regions. In response to severe water shortages in Central Yunnan, China, the government has invested over 100 billion yuan in the Central Yunnan Water Diversion Project (CYWDP). However, the project’s effectiveness in mitigating water shortage risks and addressing spatiotemporal inequality in receiving areas remains unclear. Accurate assessment and prediction of these impacts are vital for sustainable development in the region. This study enhances existing evaluation models by incorporating water shortage duration into severity assessments and introduces a simplified concentration index to measure spatiotemporal inequality, creating an integrated framework for risk and its inequality evaluation. The framework evaluates these impacts at monthly, quarterly, and annual time scales, using the smallest water receiving unit as the spatial scale. Key findings include: (1) Water shortage risk in the receiving area shows strong seasonal patterns, with spring being the highest-risk period. Annual risk variability is significant and strongly negatively correlated with precipitation (-0.8). Water supply security is only guaranteed in years of abundant rainfall, as local developable water resources are limited, with approximately 80% of years falling into moderate-risk zones. (2) Spatial inequality in water shortage risk is evident, driven by variations in precipitation, groundwater availability, and water storage infrastructure. Intra-annual risk disparities are more pronounced during dry years compared to wet years. (3) Without CYWDP’s supplementary water supply, the receiving area is projected to enter a high-risk zone by 2030 and 2040. However, with the CYWDP, the overall risk is expected to decrease to a moderate level by 2030, and by 2040, increased water transfers could alleviate risks and resolve spatial inequality. This study provides critical insights for evaluating the socio-economic benefits of the CYWDP and guiding water resource allocation strategies. The proposed framework also serves as a valuable reference for similar studies globally.