【摘要】 震区山洪泥石流频发严重已引起国内外的广泛关注,进行山洪泥石流野外监测,研究其发育和演化特征,对保障灾区公共安全和进行防灾减灾管理具有重要意义。本文以汶川地震震中莲花芯沟为研究区,选择不同类型的坡面泥石流和沟道泥石流,在坡面、沟道和典型小流域建立山洪泥石流野外观测站点,采用现代测绘和三维激光扫描技术,利用大地测量、GPS、3D激光扫描系统和高分辨率遥感影像等手段,进行了不同降雨条件下的山洪泥石流坡面、沟道、断面和小流域地表形变监测,构建高精度DEM,研究了坡面泥石流和沟道泥石流的侵蚀、发育和演化特征,分析了泥石流的变形破坏、冲淤变化和演化规律。研究结果表明:(1)震后4年山洪泥石流灾害日趋频繁且仍处于快速发育阶段,采用现代测绘和3S技术可以进行山洪泥石流灾害野外监测与侵蚀产沙定量分析;(2)沟道上游山洪泥石流活动强烈,具有大冲大淤特征,总体上以冲刷侵蚀为主,其断面中部下切侵蚀速率为3.98m/a,两侧坡体呈现左淤右冲特征,一场泥石流最大冲刷下切深度达5m;(3)沟道中游总体上仍呈现冲刷侵蚀,但强度减弱,断面中部侵蚀速率为1.23m/a;(4)沟道下游防治工程修建前呈现较强的冲刷下切侵蚀、平均冲刷深度达1.7m,修建谷坊后拦蓄停淤作用明显,沟道总体呈现淤积,淤积速率为2.05m/a;(5)自然状态下研究区一场山洪泥石流冲出物质量约1.6万m3、平均冲刷深度为0.23m/a,谷坊等防治工程修建后具有较好地稳沟固坡作用,山洪泥石流则表现为较强的淤积特征,一场山洪泥石流产沙淤积量为1.7万m3。研究结果可以为山洪泥石流灾害的综合研究提供数据支持,同时也可为灾区公路泥石流防治工程设计、监测预警和风险管理提供科学依据。更多还原

【Abstract】 The flash flood and debris flow in the suffered areas by Wenchuan earthquake aroused a wide attention at home and abroad because of their tremendous damage and frequent occurrence. It is significant to conduct field monitoring of flash flood and debris flow and to study their development features for assuring public security and preventing flash flood and debris flow. In this paper, Lianhuaxin gully, the epicenter of Wenchuan Earthquake, was taken as a study area and different kinds of slope debris flow and gully debris flow were selected to make field surveying. Three-level field observation stations and 56 control points were established in different slope, ridge, submit and small watershed of study area. From 2010 to 2012, four large-scale flash-flood debris flows and corresponding slopes, channels, sections and surface deformations were monitored by means of GPS, total station, leveling instrument, 3D-laser scanning system, InSar and high-resolution images. Three-dimension digital terrain models with large scale were set up to study the erosion, development and evolution features of different kinds of debris flows. The paper also discussed the fluvial process and erosion-deposition characteristics of flash flood debris flow. The results show that: (1) flash flood and debris flow are still at rapid development stage after earthquake, become more and more frequent and can be monitored through 3S technologie; (2) in the upper reaches of study area, flash-flood debris flow is typical of violent erosion and deposit with serious erosion at the incision ratio of 3.98m/a in the middle and right slope and even with the maximum incision depth of 5m at a debris flow event but with moderate deposit on the left slope; (3) the middle reaches of gully are still characterized by serious erosion with the maximum incision depth of 3m but its intensity decreased with the incision ratio of 1.23m/a; (4) the lower reaches of gully generally have a moderate erosion with the average incision depth of 1.7m but have a transparent deposit after 6 check dams were established along the main gully, with the deposit ratio of 2.05m/a; (5) before check dams established, a flash-flood debris flow event eroded and yieled about 1.6×104m3 with the average erosion depth of 0.23m/a but deposited and yieled about 1.7×104m3 after established check dams. The findings can provide data for comprehensive study of flash-flood debris flow and scientific basis for control engineering design, monitoring and warning and risk management of debris flow.更多还原