基于斜坡单元与多尺度降雨工况下的地质灾害风险调查评价

Geohazard risk investigation and assessment based on slope units with multi-scale rainfall conditions

关键词:  地质灾害  高精度地灾调查  斜坡单元  多尺度降雨工况  风险评价

Key words:  geohazard  high-precision geohazard survey  slope unit  multi-scale rainfall conditions  risk assessment

摘要:

开展科学有效的地质灾害风险调查评价对摸清区域地质灾害底数、防灾减灾具有重要作用。以诸暨市马剑镇为研究对象进行斜坡单元划分，并对全镇开展1∶2000的逐坡调查；提取调查结果中的九项因子，采用综合指数法和不同降雨工况下的24 h最大降雨量作为地质灾害发生的诱因，对各斜坡单元进行地质灾害易发性、危险性定量评价；再通过对承灾体的易损性识别，最终确定了每个斜坡单元的综合风险等级。结果表明：随着降雨阈值的提高，研究区内中风险及以上斜坡单元逐渐增多；在特大暴雨工况下，马剑镇存在极高风险区1处；高风险区9处；中风险区16处。通过大比例尺下的精细化调查，并结合浙江省沿海多雨的孕灾气象条件对地质灾害进行风险评估，为探索我国东南沿海地区高精度的地质灾害风险调查评价体系提供了可靠依据。

Abstract:

Background, aim, and scope Geohazards pose significant threats to human life and property. Scientific and efficient risk assessment is essential for regional mapping, disaster prevention, and mitigation. This study investigates geohazard risk in the southeastern coastal region of China by integrating diverse rainfall conditions with large-scale, high-precision surveys, with the aim of providing guidance for further research into geohazard risk assessment in coastal mountainous region. Materials and methods The study area, centered on Majian Town in Zhuji City, was divided into slope units. A comprehensive 1∶2000 slope-by-slope survey was conducted across the town using an integrated approach combining remote sensing interpretation, DEM data analysis, and field investigation. Results The investigation identified the disaster-prone geological background of Majian Town and the exposures within each hazard zone. Nine factors were extracted from the survey data, and the integrated index method, along with 24-hour maximum rainfall under varying conditions, was applied to quantify geohazard susceptibility and hazard levels for each slope unit. By assessing the vulnerability of exposures, the comprehensive risk level of each slope unit was determined. Results showed that the number of slope units with moderate or higher hazard and risk increased with rising rainfall thresholds. Under extreme rainfall conditions, Majian Town contained one very high risk, nine high risk, and sixteen medium risk slope units. Discussion The geohazard susceptibility and risk assessment model was quantitatively, validated using normal distribution analysis and ROC curves, confirming that the results aligned with objective patterns and demonstrated reliability. A comparison with the previous 1∶50000 geohazard risk investigation indicated that the 1∶2000 assessment achieved higher accuracy due to improved survey resolution, more precise baseline data, and refined rainfall factor calculations. These findings highlight the importance of large-scale assessments using slopes as the fundamental units and individual houses as distinct exposures, shifting the focus from single-hazard evaluations to comprehensive assessments of geohazard risks and underlying geological. Conclusions The refined large-scale survey and geohazard risk assessment, combined with the rainfall-prone meteorological conditions of coastal Zhejiang Province, provide a solid foundation for developing a high-precision geohazard risk survey and assessment system for southeastern China’s coastal regions. Recommendations and perspectives Future research should focus on optimizing geohazard risk assessment methods to enable more accurate risk prediction, advance the transition from static hazard management to dynamic risk and hazard control, and strengthen studies on geohazard thresholds under varying rainfall intensities.