Risk assessment of landslide geological hazards under different rainfall conditions based on P-III curve
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摘要: 摘 要:【目的】降雨是诱发滑坡崩塌等地质灾害的重要因素之一,极大的威胁着群众的生命财产安全,为有依据的采取防治措施以及避险搬迁。【方法】本文以叶枝镇为研究区,选取高程、土地利用类型、坡度、坡向、地貌类型、工程地质岩组、土地利用类型、河流距离、断层距离、曲率等9个评价因子,以栅格单元作为评价单元,采用随机森林算法和加权信息量法对评价因子进行权重分析,作出易发性评价,并再此基础上选择降雨量作为危险性评价因子,通过计算和皮尔逊Ⅲ型曲线预测研究区十年一遇、二十年一遇、五十年一遇、百年一遇的降雨量,得出4种不同的降雨工况,作出危险性评价。【结果】由统计所得,将易发性评价结果按照自然间断点法分成低、中、高、极高易发区4个等级,分别占据研究区面积32.8%、34.02%、21.96%、11.22%,用ROC曲线对其作精度验证,AUC值为89.2%;4种降雨工况条件下的地质灾害危险性评价结果,分别分出低、中、高、极高危险区4种等级,并对评价结果进行对比分析。【结论】通过与实际调查情况对比,本文得出的崩滑地质灾害危险性评价结果与实际情况较为吻合,能够为防灾减灾、避险搬迁提供合理依据。Abstract: [Objective] Rainfall is one of the important factors that induce geological disasters such as landslides and collapses, posing a great threat to the safety of people's lives and property. Therefore, it is necessary to take effective prevention and control measures as well as to avoid and relocate. [Methods] This article takes Yezhi Town as the study area, the grid unit is used as the evaluation unit. 9 evaluation factors including elevation, land use type, slope, aspect, elevation, landform type, engineering geological rock group, land use type, distance from river, distance from fault, curvature were selected. Using Pearson correlation analysis, the correlation between the 9 factors is weak, can participate in subsequent calculations. The Random Forest algorithm was used to analyze the feature importance of 9 factors, based on the feature importance, obtain a weighted information model that combines subjective and objective factors, using this model as a susceptibility evaluation for collapses and landslides. Then select rainfall as the risk assessment factor. Predicting the rainfall of the study area once in 10 years, once in 20 years, once in 50 years, once in 100 years through calculation and P-III curve, and import the data into ArcGIS, utilizing the raster calculator function, four different rainfall conditions were obtained. Then superimposing the rainfall conditions and the susceptibility assessment model to obtain the risk assessment. [Results] According to the statistics, he susceptibility assessment results are divided into four levels using the natural discontinuity method: low, medium, high, and extremely high susceptibility areas, which occupied 32.8%, 34.02%, 21.96% and 11.22% of the study area respectively. ROC curve was used to verify the accuracy, and the AUC value was 89.2%, falling into a better range. The risk assessment results of the four rainfall conditions were divided into four grades according to a certain range: low, medium, high and extremely high risk zones. The results of geological hazard risk assessment under different rainfall conditions is determined. [Conclusion] By comparing with the actual investigation, the landslide and collapse risk assessment results under different rainfall conditions are highly consistent with the actual situation. This article can provide a basis for reasonable disaster prevention and mitigation, as well as risk avoidance and relocation. Subsequently, a comparative analysis will be conducted on the selection of evaluation units to select the most suitable evaluation unit for the study area. I will also apply InSAR to identify hidden danger points of geological disasters in high altitude areas that are difficult for people to reach in the study area, and apply hidden danger point data to the susceptibility evaluation and risk assessment system.
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