Urban ecological risk assessment under water resources constraints: Framework development and application in Chinese cities

Rapid urbanization is intensifying the pressure on urban ecological systems, leading to a rise in urban ecological risks (UER). While traditional risk assessment frameworks, such as the Hazard-Exposure-Vulnerability (HEV) model, have been widely used, they often overlook a critical dimension: water resource constraints (W). This oversight results in a simplified understanding of UER, especially in water-scarce regions. Our study addresses this research gap by developing a novel UER_HEVW framework that integrates water resource constraints directly into the classic UER_HEV model. We constructed the UER_HEVW index and applied it to 371 cities in China. The results indicated that integrating water resource constraints substantially altered risk patterns, with 16.13 % of the cities increasing by at least one risk category. Shanghai, Chengdu, Kashgar and several cities in the Pearl River Delta experienced upgrades of up to two classes. Such shifts highlight newly identified risk hotspots, particularly in cities with high population density and high water consumption. Furthermore, this study found that urban green space factors, such as the proportion of forest and grassland area, played a significant role in mitigating ecological risks. Therefore, strategies for addressing urban ecological risks should not be limited to simply restricting urbanization processes, but should also focus on enhancing the resilience of urban ecosystems through green space planning and other measures. Given that the complexity and multi-dimensional nature of urban ecological risks make them difficult to identify intuitively, a systematic diagnostic framework that integrates water resource constraints is crucial for precise identification and effective risk management.