汶川县渔子溪流域泥石流源区的崩滑体空间分布特征

Spatial Distribution Characteristics of Landslides and Collapse Masses in Debris Flow Formation Region along the Yuzixi River Basin of Wenchuan County,Sichuan Province

为了明确崩塌滑坡转化为泥石流的特点,研究泥石流源区内的崩塌滑坡体特征,以映秀至卧龙间渔子溪流域为研究重点,划分研究区约396 km2,以研究区内23条泥石流沟（流域总面积约为208 km2）作为研究对象,利用高精度遥感影像将崩塌滑坡点进行解译,并通过野外实际调查进行复核,证实了遥感解译的可靠性,最终得到崩塌滑坡点2 741个,总面积23.6 km2。利用GIS对崩塌滑坡在高程、坡度、坡向、地层岩性和河流距离的分布特征进行了分析,结果表明：在1 500-3 000 m海拔范围内,崩塌滑坡分布最多;坡度40°-50°范围,崩塌滑坡面积比例最大;坡向在90°-180°范围较为集中,此范围垂直于地震断层;崩塌滑坡较坚硬闪长岩岩组容易被地震、降雨等因素触发大量崩塌滑坡;距离河流较近的山体容易发生崩塌滑坡。

In order to understand the characteristics of landslides and collapse masses transforming into debris flow,we researched the landslides and collapse masses in debris flow formation area. In this paper,we took Yuzixi river basin between Yingxiu county and Wolong county as research area and 23 debris flow gullies as research objects.Area of the study region is about 396 km2,and total area of debris flow basin is about 208 km2.On the basis of interpretation of the landslide and collapse points with high resolution remote sensing images,in association with field investigation,we confirmed the reliability of the remote sensing interpretation,and finally obtained 2 741 disaster points with an area of 23.6 km2. Then we employed GIS to calculate the distribution of the landslides and collapse points in aspects of elevation,gradient,dip,lithology and distance from the river. Results show that,firstly,most landslides and collapse masses exist in the elevation of 1 500-3 000 m; secondly,the area ratio of landslides and the collapse masses with slope gradient of 40°-50° is the largest; thirdly,slope direction is concentrated in the range of 90°-180 °,and slope direction of the range is perpendicular to the earthquake fault; furthermore,under earthquake or heavy rainfall,harder diorite easily leads to a large number of landslides and collapse masses; finally,landslide and collapse easily break out when mountains are near the river.