Dynamic adjustment methods for geological hazard risk zones

To support China’s strategic transition in geological hazard management from Static Potential Hazard Management to Dual Control of Potential Hazards and Risks of Geological Hazards, and to address issues such as redundant early warnings and heavy management pressure on risk zones under the current static management model, it is urgently necessary to establish a theoretical method for dynamic adjustment of geological disaster risk zones. Based on a systematic clarification of the fundamental concepts and dynamic attribute characteristics of risk zones, this study elucidated the scientific logic of dynamic risk zone management and explored the construction of a dynamic adjustment index system (comprising three primary indicators: changes in hazard sources, changes in elements-at-risk, and historical prevention effectiveness, and encompassing six second-level indicators: engineering mitigation, current deformation status, significant geological environmental changes, static and dynamic elements-at-risk, and early warning efficiency). For regions with insufficient historical warning data, a method for constructing a qualitative identification matrix for risk zones was proposed. For regions with adequate warning data, a quantitative adjustment model was innovatively established by introducing the quantified indicator of warning efficiency. Taking Lin’an District, Hangzhou City, Zhejiang Province—a pilot area for the Dual Control of Potential Hazards and Risks of Geological Hazards in China—as a case study, this study conducted dynamic adjustment practice and warning effect inversion for 235 risk zones based on retrospective analysis and field verification of over 100,000 historical meteorological warning and management data records. The results demonstrate that the proposed method can achieve scientific determination of upgrading, maintaining, downgrading, cancellation, and addition of risk zones. In the study area, extremely high-risk zones, accounting for only 4% of the total, contributed to as high as 60% of all warnings, with an average of as many as 123 warnings per zone annually, highlighting a prominent warning redundancy problem. After adjustment using this method, the number of extremely high-risk zones in the area decreased by 61%, and the number of hourly early warnings decreased by about 60%. Moreover, the adjusted warning results align with actual hazard occurrences. The dynamic adjustment method for risk zones proposed in this study can scientifically respond to the dynamic attributes of geological hazard risks, significantly enhance the precision and efficiency of meteorological early warning and risk management for geological hazard risk zones, and provide a replicable solution and practical model for China’s comprehensive promotion of the Dual Control of Potential Hazards and Risks of Geological Hazards.