基于GIS的延河流域滑坡崩塌地质灾害空间分布及其引发因素分析

目的]以更符合滑坡崩塌发生发展规律的延河流域为例,进行地质灾害空间分布及引发因素分析研究,为防灾减灾提供依据。方法]依据区县地质灾害详细调查资料,建立GIS地质灾害数据库,包含地理数据、基础地质数据、地质灾害点数据和栅格数据。统计分析坡度、坡高、坡型、河谷发育期等引发因素;选取坡度、坡型、植被、河谷地貌、地层、降雨量、道路距离、居民点8因素,采用加权信息量法进行地质灾害易发性分区阐述地质灾害空间分布。结果]坡高50~100m,坡度30°~45°易形成滑坡;老年河谷灾害点密度为壮年期的2倍,幼年期的3倍;凸型和直线型斜坡更容易产生滑坡和崩塌灾害,阶梯型和凹陷型斜坡稳定程度明显增高。延河流域滑塌高易发面积1 664.96km2,灾害点密度0.29处/km2;中易发3 102.02km2,密度0.10处/km2;低易发3 888.99km2,密度0.04处/km2。结论]以流域为单位进行地质灾害研究,引发因素、空间分布规律更为明显,指导防灾减灾更加实用。

A GIS-based Research on Triggering Factors of Erosive Landslide and Collapse in Yanhe River Basin

Objective] The occurrence and development of landslide and collapse in Yanhe River were taken as an example, the spatial distribution and triggering factors of geological disasters were analyzed in order to provide a basis for disaster prevention and mitigation. Methods] According to the detailed geological disaster investigation, GIS geological hazards database was constructed, including geographic data, basic geological data, geological disaster points'' data and raster data. Triggering factors, such as slope gradient, slope height, slope type, and valley development, etc., were statistically analyzed. Slope ratio, slope type, vegetation, river valley landforms, stratigraphy, rainfall, residential position, road distance were selected to elucidate the spatial distribution of geological disasters with susceptibility zoning by weighted information method. Results] Analysis of triggering factors of landslide and collapse showed that landslide were found more frequent in the case with 50 to 100 m slope height and 30° to 45° grade. The density of disaster points in elderly valley is 2 times of the mature stage and 3 times of the juvenile stage. Convex and linear shape slopes are more prone to landslides and collapses; the stability of staircase or umbilicate slope are significantly increased. The acreage of high-prone area is 1 664.96 km². The density of disaster points is 0.29 point/km². The middle prone area is 3 102.02 km². with disaster density of 0.10 point/km². And the low-prone area is 3 888.99 km², with disaster density as 0.04 point/km². Conclusion] Geological disasters, if investigated in a river basin, its triggering factors and the spatial distribution will be more easily recognized. And disaster prevention and mitigation are more applicable taking a river basin as unit.