INFORMATION AND LOGISTIC REGRESSION MODELS BASED COUPL-ING ANALYSIS FOR SUSCEPTIBILITY OF GEOLOGICAL HAZARDS
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摘要: 汶川地震在区内诱发了大量滑坡、崩塌等地质灾害,且孕育了大量松动岩体,这些松动岩体在降雨等因素诱发下将会产生大量次生地质灾害,危险性极大。故此对汶川县进行地质灾害易发性评价具有十分重要的现实意义。本文选取高程、坡度、坡向、起伏度、沟谷密度、工程岩组、断层、水系、道路9个影响因子,基于GIS的栅格数据模型,采用信息量模型、Logistic回归模型以及两种模型耦合分析进行地质灾害易发性评价。研究结果表明,采用耦合模型较信息量或Logistic单一模型评价结果更加合理、精度更高;易发性高与较高区域多集中于水系延展区域与断层集中区域。所计算得出的易发性分区结果与研究区实际情况相近,能在地质灾害风险评价中起到重要参考作用。Abstract: Wenchuan earthquake induced a large amount of geological disasters such as landslides and collapses. Besides, the earthquake also caused a lot of the loose and broken rock mass. Those loose rock mass can produce large amounts of secondary geological disasters under the rainfall and other factors, which has great danger. Therefore, it has very important practical significance for geological disaster susceptibility evaluation of Wenchuan country. Based on GIS raster data model, this paper selects nine factors including elevation, gradient, slope direction, relief amplitude, gully density, the engineering rock group, fault, drainage and roads. It adopts the information, logistic and information-logistic coupling models for assessment of geological hazards. The results show that the coupling model is more reasonable and has higher precision. High and very high susceptibility of geological hazard areas are concentrated in the water extension area and fault concentration area. Susceptibility partition map of the calculation results is consistent with the actual situation of the study area and can play an important reference role in the geological hazard risk assessment.
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表 1 各评价因子状态信息量值
Table 1. Status information of each evaluation factor
指标因子 分级 信息量 指标因子 分级 信息量 高程/m 784~1200 3.42 工程岩组 软硬互层岩体 0.94 1200~1700 2.23 软质岩体 -0.18 1700~2200 0.59 硬质岩体 -0.10 2200~2700 -1.23 道路缓冲区/m < 200 -0.75 > 2700 -3.80 200~400 0.46 坡度/(°) 0~10 2.63 400~600 0.48 10~20 1.01 600~800 0.48 20~30 0.07 800~1000 0.50 30~40 -1.33 > 1000 -0.03 > 40 -1.74 水系缓冲区/m < 200 2.35 起伏度/m < 245 1.36 200~400 2.69 245~366 0.05 400~600 2.82 366~493 -0.77 600~800 1.88 493~650 -1.48 800~1000 1.14 > 650 -1.96 > 1000 -0.59 沟谷密度 0.38~0.53 -3.39 坡向 N -0.83 0.53~0.59 -2.00 NE -0.15 0.59~0.64 -0.05 E 0.13 0.64~0.70 0.85 SE 0.48 0.70~0.85 1.70 S -0.57 断层缓冲区/m < 500 1.54 SW -0.47 500~1000 1.56 W 0.12 1000~1500 0.50 NW 0.55 1500~2000 0.39 > 2000 -1.33 表 2 各个易发性区灾害点分布表
Table 2. Disaster distribution of each liability area
易发性 灾害点比例/% 耦合模型 信息量模型 Logistic回归模型 低易发性 2.76 2.47 3.12 较低易发性 2.33 3.20 3.31 中易发性 6.54 11.34 7.89 较高易发性 10.73 18.90 16.13 高易发性 77.64 64.10 69.55 -