基于无人机遥感技术的汶川震区典型高位泥石流动态监测——以绵竹市文家沟泥石流为例

Monitoring of a typical high position debris flow dynamic change in Wenchuan earehquake areas with unmanned aerial vehicles case study of Wenjiagou debris flows in Mianzhu county

本文采用六期遥感影像数据,分析了文家沟特大泥石流震后的6次泥石流灾害过程;阐述并讨论了无人机遥感技术在高位泥石流动态变化监测方面的具体应用方法及应用效果。以汶川震区文家沟泥石流为研究对象,本文主要得到以下几点认识:(1)文家沟流域物源丰富,泥石流发生频率高、松散物质冲出量大、主沟比降较大,是汶川地震灾区典型的特大型高频高位泥石流。(2)水动力条件、地形坡度和堆积物颗粒大小是文家沟泥石流物源启动的三个主要制约因素。(3)不同降雨条件下,文家沟泥石流具有复合型物源启动方式,先主沟下游沟道松散堆积启动形成泥石流,进而演变为下游主沟沟道和流域上游崩滑物源相继启动,全流域形成泥石流;(4)工程治理约束条件下,文家沟泥石流暴发规模、破坏模式和成灾形式均发生重大转变。(5)在非极端气候条件及工程治理设施继续发挥效力情况下,未来几年内,文家沟泥石流仍然是以上游处3号、4号、5号支沟继续形成小规模泥石流为主,危害方式主要是淤埋4号坝和5号坝,并逐步减少库容。(6)泥石流的动态变化监测方法,是以多期次高精度遥感影像和大比例地形图获取的基础上开展的,遥感数据源和大比例尺地形图精度是影响该方法应用效果的主要因素。

This paper utilizes remote sensing data of 6 stages to analyze the 6 hazard processes of Wenjiagou debris flow after Wenchuan earthquake,and then to describes and discusses the application effect of high debris flow dynamic change monitoring using unmanned arial vehicles UAV remote sensing technology. After the research on Wenjiagou debris flow,this paper has the following conclusions: 1). Wenjia Valley has numerous source,and the debris breaks out with high frequency,and the run out volume of unconsolidated material is large,and the longitudinal gradient is also high. The Wenjiagou debris flow is a typical extra large high position debris flow with high frequency in Wenchuan earthquake area. 2). The hydrodynamic condition,the topographic slope and the particulate size of deposition are the main three restrictions of failure of Wenjiagou debris material source. 3). Under different precipitation conditions,Wenjiagou debris flow has complex material source failure modes. First unconsolidated deposition in the downstream of the groove failed,then the material source in the main groove of downstream and the block collapsed material source in the upstream of the watershed failed successively. Finally,the debris flow formed in the whole watershed. 4). Under the restriction of engineering control,the break out extent,the damage mode and the hazard form type changed greatly. 5). If extreme weather does not exist and the engineering control still works,in the next years,the majority of Wenjiagou debris flow are the No. 3,4,5 tributary valley forming small scale debris flows in the upstream. The damage mode is to deposit No. 4 and No. 5 dam and reduce the dam volume. 6). The dynamic change monitoring method of debris flow is based on high resolution images of multiple stages and large scale topographic maps. The quality of data source and large scale topographic maps is the main factor which influences the method.