Assessing ecological risk (ER) is crucial to preventing risk and mitigating ecological deterioration in semi-arid river basin areas.Ningxia Hui Autonomous Region, the second-largest river in China flows through. Ningxia is positioned at the convergence of three major natural regions in China and showcases distinctive geographical features and noteworthy climate variations. This paper employs a regional ecological risk assessment model and a random forest model to evaluate all counties in Ningxia. Through an analysis of the ecological risk causal chain, a set of 29 indicators is chosen to construct an ecological risk assessment system, encompassing ecological risk sources, environmental fragility, and risk receptor losses. Examining the 2000-2020 spatiotemporal distribution of regional ecological risk and risk gravity shifts furnishes strategic recommendations for ecological risk prevention in Ningxia. The findings indicate that ecological risk in Ningxia is relatively low, displaying a diminishing pattern from northwest to southeast. With longitudinal changes prevailing during the study period, the shift in the movement direction of the ecological risk center from southwest-northeast to southeast-northwest is observed. High-risk areas are predominantly confined by ecological factors, hinting at potential enhancements by establishing contemporary flood control systems and ecological protection measures. In the Moderate-risk areas, local authorities are called for harmonized efforts to coordinate the relationship between ecological protection and industrial development, fostering the Yellow River Basin's ecological preservation and high-quality development.

ecological risk; spatiotemporal distribution;shifting of risk gravity