基于ArcGIS+DEM的三眼峪泥石流水动力条件分析

Analysis on the Hydrodynamic Conditions for the Massive Debris Flow in Sanyanyu Based on ArcGIS and DEM

通过对甘肃省舟曲三眼峪特大泥石流灾害的现场调查,从泥石流形成的地形地貌条件和水动力条件入手,以A rcG IS为平台,运用DEM数据,分析了特大泥石流灾害的三区地形地貌特征、固体松散物特征、降雨特征以及泥石流静力学和动力学特征。结果表明:三眼峪三区为泥石流的形成和径流流通提供了极为有利地形条件;固体松散物质补给量潜力巨大,会导致堰塞坝的放大效应;诱发此次特大山洪泥石流是一场局地性、短时强度大的暴雨过程,泥石流容重在2.10 t.m-3左右,属于高容重黏性泥石流;泥石流屈服应力在8 000 Pa以上,大小眼峪(降雨汇流区)及三眼峪(泥石流堆积区)泥石流流速分别为8.97 m/s、7.06 m/s和6.02 m/s,洪峰流量分别为1 659 m3/s、1 553 m3/s和1 896 m3/s,冲击力分别为46 676 tf、40 236 tf和21 182 tf,其破坏力巨大,危害严重,使得泥石流在汇流区破坏力巨大以切蚀为主,受地形影响,三眼峪出口处,冲击力减小,泥石流发生堆积。

The terrain and topographical characteristics loosening solid matter characteristics and rainfall characteristics as well as statics and dynamic characteristics of giant debris flow were obtained by field investigation and analysis on the debris flow hydrodynamic force conditions based on platform of ArcGIS and using DEM. The results show that the terrain and topographical can provide favorable condition for formation and running of runoff. The amount of loosening solid matter is so great that amplify dam. The severe local weather process with heavy precipitation short duration is the main cause for this massive mudslide. The bulk density of debris flow is 2.10 t/m^3, is high density viscous debris flows, and yield stress is over 8 000Pa, the velocity of dayanyu xiaoyanyu （rainfall confluence area） and sanyanyu （debris flow accumulation area） is respectively 8.97 m/s, 7.06 m/s, 6.02 m/s, the maximum flow is 1 659 m^3/s, 1 553 m^3/s, 1 896 m^3/s, the impact force is 46 676 tf, 40 236 tf and 21 182 tf, so the destructive power is great and its damage is serious. The great destructive of debris flow in circulation terrain is mainly down cutting erosion, affected by the terrain, the impact force is decreased and the debris flow stacked.