不同降雨工况条件下的崩滑地质灾害危险性评价

Geological hazard risk assessment of collapse and landslide under different rainfall conditions

为针对性地采取预防、避让、治理等地质灾害防治与管控提供依据,完善在地质灾害危险性评价中将降雨作为单一诱发因子参与评价体系的弊端,在大雨、暴雨、大暴雨和特大暴雨4种不同降雨工况条件下进行了研究区崩滑地质灾害危险性评价。以云南省元阳县作为研究区域,以栅格单元作为评价单元,选取地貌类型、高程、坡度、坡向、曲率、工程地质岩组、土地利用类型、断层距离和河流距离9个评价因子,采用主观的层次分析法与客观的信息量模型相结合的加权信息量模型对元阳县崩塌、滑坡进行了地质灾害易发性评价。研究结果表明:基于自然间断点法元阳县域可分为低、中、高、极高4类易发区,4类易发区面积分别占元阳县面积的21.55%,35.46%,25.53%和17.16%。利用ROC曲线得出区划结果精度AUC值为0.812,表明区划结果很好。在易发性评价基础上,以年平均最大日降雨量为诱发因素,分别对大雨、暴雨、大暴雨和特大暴雨4种工况条件下的研究区进行了崩塌、滑坡地质灾害危险性评价,得到了大雨([25,50) mm)工况、暴雨([50,100) mm)工况、大暴雨([100,250]mm)工况和特大暴雨(>250 mm)工况4种条件下基于极值假设的研究区崩滑地质灾害危险性评价结果,并对不同降雨工况条件下的地质灾害危险性评价结果进行了对比分析,确定了地质灾害危险性评价结果在不同降雨条件下的空间合理性。通过与实际调查结果的对比表明,4种不同降雨工况条件下的崩滑地质灾害危险性评价结果与实际高度吻合,说明评价结果具有较高的可靠性与合理性。

[Objective]This study provides a basis for the prevention,avoidance,management and control of geological hazards.The disadvantage of considering rainfall as a single inducing factor in the evaluation system of geological hazard risk should be overcome.In this paper,risk assessments of collapse and landslide geological hazards in the study area were carried out under four different rainfall conditions:heavy rain,rainstorms,heavy rainstorms and extraordinary rainstorms.[Methods] Yuanyang County,Yunnan Province,was selected as the study area,and the grid unit was chosen as the evaluation unit.Nine evaluation factors were selected,namely,landform type,elevation,slope,aspect,curvature,engineering geological rock group,land use type,distance from fault and distance from river,respectively.A weighted information model combining a subjective analytic hierarchy process and an objective information model was used to evaluate susceptibility to collapse and landslides in Yuanyang County.[Results] According to the natural discontinuity point method,Yuanyang County is divided into four types,low,medium,high and extremely high susceptibility areas,accounting for 21.55%,35.46%,25.53% and 17.16% of the area of Yuanyang County,respectively.According to the ROC curve,the accuracy of the zoning results was 0.812,and the zoning results were good.Based on the susceptibility assessment,taking the annual average maximum daily rainfall as the inducing factor,risk assessments of collapse and landslide geological hazards in the study area were carried out under four working conditions-heavy rain,rainstorm,heavy rainstorm and extraordinary rainstorm,and results for collapse and landslide geological hazards under four conditions:heavy rain([25,50) mm) and rainstorms([50,100) mm),heavy rainstorm([100,250] mm) and extraordinary rainstorm(>250 mm) data were thus obtained.The results of geological hazard risk assessments under different rainfall conditions are compared and analysed,and the spatial rationality of geological hazard risk assessment results under different rainfall conditions is determined.[Conclusion] The collapse and landslide hazard evaluation results under different rainfall conditions are highly consistent with the actual survey results,confirming the high reliability and rationality of the evaluation results.