李文彦 胡帅军 张帆宇

摘 要：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。

关键词：Flow-R;山洪;泥石流;易发性评价;敏感性分析

中图分类号：P694;TV144 文献标志码：A

doi：10.3969/j.issn.1000-1379.2021.05.011

Abstract： 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.

Key words： Flow-R model; mountain torrent; debris flow; susceptibility assessment; sensitivity analysis

近年來，黄土高原地区极端气候频发，汛期降雨量通常占全年降雨量的75%～85%。兰州地区地形切割严重，是典型的黄土沟壑区，且快速的城镇化建设对地形植被破坏严重，使得原本脆弱的生态环境更易发生山洪、泥石流等灾害，严重制约着当地的经济、社会发展[1-2]。例如2018年7月20日，兰州市11个雨量站出现暴雨到大暴雨，局部地区降雨量达111.8 mm。暴雨诱发北山发生多处山洪与泥石流灾害，主城区形成17处积水内涝点，交通系统瘫痪。山洪与泥石流形成条件相近，但其本质存在明显差异，山洪以水为主，流动性强，而泥石流碎屑物质较多，流动性差[3]。易发性评价是山洪与泥石流灾害评价的基础环节，在研究区开展山洪和泥石流易发性对比研究，可为深入分析其灾害性和风险性提供重要资料，对制定相关防灾治理措施及土地开发规划有重要的指导性。……