兰州大沙沟流域山洪与泥石流易发性比较分析

Comparative Analysis of the Susceptibility of Mountain Torrent and Debris Flow in Dashagou Watershed of Lanzhou

黄土高原地区生态环境脆弱,在汛期的强降雨作用下常发生严重的山洪与泥石流灾害,严重影响当地的经济发展。采用Flow-R模拟软件评价兰州市大沙沟流域的山洪与泥石流易发性,分析高程、坡度、平面曲率、岩性4个因子的敏感性,最后分析易发区与关键因素之间的空间关系。结果表明:山洪易发区多位于西侧丘陵区,而泥石流易发区多位于东侧主沟内;因山洪流动性较强,故受平面曲率的影响有限,山洪的平面曲率敏感性<1,诠释了二者的差异性;人类活动对地形地貌和岩土体的扰动是造成山洪和泥石流易发性差异的重要因素,同时诱发的山洪、泥石流对工程活动造成严重威胁。

The eco⁃environment in the northwest loess plateau region is fragile,and severe mountain torrent and debris flow often occur under heavy rainfall during the summer flood season,which directly affects the local life and property security and economic development.Flow⁃R debris flow simulation software was used to evaluate the susceptibility of mountain torrent and debris flow to the Dashagou watershed in Lanzhou City and the sensitivity of elevation,slope,plane curvature and lithology was analyzed.Finally,the spatial relationship between the susceptible area and key factors was analyzed.The results show that the mountain torrent susceptible areas are mostly located in the hilly area on the west side,while the debris flow susceptible areas are mostly located in the main channel on the east side.Due to the strong flow of mountain torrents,the effect of plane curvature on mountain torrent is minimal.The plane curvature sensitivity of mountain torrent is less than 1,which explains the difference between each other;the disturbance of topography and geomorphology and rock⁃soil body by human activities is an important factor that causes the difference in the susceptibility of mountain torrents and debris flows and the induced mountain torrents and debris flows pose a serious threat to engineering activities.