甘肃省武都区马槽沟泥石流特征及其治理工程效应

Analysis of mitigation strategies in Macaogou debris flow valley,Wudu,Gansu Province

调查了马槽沟泥石流沟的地形地貌、地层岩性、松散物源、降雨等地质环境条件和人类工程活动情况,对比分析1990年竣工和"5.12"汶川地震后新修建的治理工程,研究其工程治理效应.结果表明马槽沟泥石流属中易发粘性泥石流.1988年马槽沟实施的拦挡工程使主沟道沟床比降由7.5%降为5.4%,起到了消减洪峰流量和泥沙输移量的作用;2009年新建拦挡工程库区淤满后,主沟道纵比降将变缓为3.77%,沟床平均宽从建坝前6.85 m淤宽到34.9m,百年一遇流量的泥石流在修建拦挡工程前后,经过沟口处的流速将减小54.4%,泥石流输移的最大粒径减小75.5%,说明马槽沟泥石流综合治理工程的实施能有效减少泥沙输出量,对扼制白龙江武都段河床淤积及长江中上游水土流失做出贡献,同时为北峪河流域泥石流灾害以及其他地区类似泥石流沟的治理提供理论依据和科学理念.

The formation conditions and basic characteristics of Macaogou debris flow valley was analyzed, and a comparative study was conducted based on two mitigation works built in 1990 and after the ＂5.12＂ Wenchuan earthquake respectively. The results showed that Macaogou valley was prone to mesoscale and viscous debris flow. The average channel gradient changed from 7.5% to 5.4% with the dams built in 1990, and the gradient was reduced to 3.77% when the new dams filled up, with the width of debris flow valley changing from 6.85 m to 34.9 m. The velocity of debris flow and the maximum grain size of solid transported by debris flow in the channel＇s mouth were reduced by 54.4% and 75.5%, respectively. It is concluded that building check dams in Macaogou valley can decrease the erosion potentials along the slope foot with a reduction of the total sediment runoff, thus contributing to curbing the riverbed deposition of Bailong River, reducing soil and water loss in the upper and middle reaches Of the Yangtze River, and providing best.strategies for disaster reduction in the region or other likely debris flow valleys in the world.