DEVELOPMENT CHARACTERISTICS AND PREVENTION SUGGESTIONS OF THE LEPA DEBRIS FLOW IN THE ANNING RIVER FAULT ZONE
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摘要: 2011年6月17日,勒帕沟发生近50年来最大的一次泥石流,经计算泥石流断面平均流速为2.03 m/s,峰值流量为200.11 m3/s,为大型泥石流,对帕勒村村民生命财产造成了巨大危害。勒帕沟上游岸坡前缘不稳定斜坡体及勒帕沟沟道内松散堆积的卵砾石为勒帕沟泥石流的主要物源。上游支沟中碎屑物块度较小,易被水流冲走,不会形成堰塞湖和溃决型泥石流。勒帕沟流域现今仍有再次暴发泥石流的可能,建议于流域中上游进行人工植树造林,在下游清理河道,进行监测预警,以实现泥石流综合防治。Abstract: The paper gives careful calculations of the maximum debris flow in the Lepa gully in June 17th, 2011, the extraordinarily serious debris flow calamities in the last fifty years. By calculation, the mean velocity of the debris flow was 2.03 m/s with a peak discharge of 200.11 m3/s. The unstable slopes in the front edge of the upper Lepa gully's river bank together with those gravels overlapped on its riverbed proved to be the main solid substance source of the Lepa debris flow. The diameter of the clastics' particle in the upper branch was small, so they are prone to be swept away by floods in the gully rather than resulting in the formation of barrier lakes or extraordinarily serious debris flow calamities. Currently, Lepa gully still has possibility of debris flow's breakout, suggestions lie in planting trees in the upper and middle reaches of the gully, cleaning riverbed in the lower reaches, setting up monitoring and warning system, to prevent the debris flow.
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Key words:
- Anning River fault zone /
- Lepa gully /
- debris flow /
- development
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表 1 泥石流糙率系数的确定[11]
Table 1. Roughness coefficients of debris flows
泥石流类型 河槽特点 比降 不同水深/m下的n值 0.5 1.0 2.0 4.0 稀性泥石流 河槽窄而陡,多跌坎与卡口,堵塞严重,河床由直径0.5~2.0 m的巨石组成 0.15~0.22 0.200 0.250 0.330 0.500 河槽多弯道和跌坎,河床由粒径0.3~0.5 m的漂石组成 0.08~0.15 0.100 0.125 0.167 0.250 河槽宽平顺直,河槽由小于0.3 m的碎石和沙砾组成 0.02~0.08 0.058 0.071 0.100 0.125 粘性泥石流 河槽陡窄弯曲,河床由巨石沙砾组成,多形成巨石堵塞及跌坎 0.12~0.16 0.056 0.067 0.083 0.100 河槽较为顺直,河床由漂石及沙砾组成 0.08~0.12 0.036 0.042 0.050 0.060 河槽宽平顺直,河床由一般小于0.3 m的碎石沙砾组成 0.04~0.08 0.029 0.036 0.042 0.050 表 2 勒帕沟中游泥石流运动特征计算
Table 2. Calculations for the characteristics of the debris flow movements in the middle reaches of the Lepa gully
地点 ρc/(t·m-3) IC/‰ RC/m VC/(m·s-1) H/m W/m QC/(m3·s-1) 勒帕沟中游 1.393 120 0.448 2.03 0.45 219.2 200.11 -
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