2024 Bank Stability Assessment and Early Warning for Typical Riverbank Sections of the Jingjiang Reach (Hubei Section), Yangtze River

Abstract

In response to the frequent bank collapses in the Jingjiang reach of the Yangtze River caused by "clear water discharge" after the impoundment of the Three Gorges Reservoir, this paper proposes a bank stability assessment and collapse early warning method based on the Analytic Hierarchy Process (AHP), taking 49 typical monitoring bank sections in this reach as the study objects. First, an evaluation system comprising six indicators—bank line status, bank geological conditions, revetment integrity, river regime changes, degree of near-bank riverbed change, and bank slope ratio change—is established. The bank stability is classified into three risk levels: red (<60 points), orange (60–80 points), and blue (≥80 points). On this basis, a discriminant matrix for bank collapse warning levels is developed by comprehensively considering the probability of collapse and the degree of hazard (including the distance from the bank to the embankment, threats to river regime stability, navigation conditions, and the safety of existing engineering structures). The warning levels are classified into Grade I (highest), Grade II, and Grade III. Applying this method to the monitoring bank sections in the Jingjiang reach in 2024, nine red-risk sections (totaling 14.3 km) and 35 orange-risk sections were identified. Post-assessment shows that all red-risk sections experienced bank collapse in 2025, achieving a 100% accuracy rate, while the accuracy rate for orange-risk sections was 71.4%. Using the 2024 measured data, early warnings for 2025 indicate that the total length of Grade I warning sections is 4.46 km, Grade II 17.62 km, and Grade III 39.89 km. Among these, Grade I warning sections such as Changjiangcun, Nongfengcun, and Lianxinyuan all experienced bank collapse in 2025. These results verify the reliability of the proposed early warning method, providing a scientific basis for bank collapse prevention and engineering management in the middle and lower reaches of the Yangtze River.