汶川震区哈尔木沟泥石流活动特征及防治

Activity Characteristics of Debris Flow in Haermu Ravine of Wenchuan Earthquake Area and the Countermeasures

摘要:

哈尔木沟位于杂谷脑河中游，属于“5?12”汶川震区重灾区，历史上多次暴发泥石流灾害，曾于1989年8月暴发泥石流堵断杂谷脑河。受“5?12”地震影响，泥石流灾害相对震前具有规模增大、频率增高、活跃期增长等特点。分析哈尔木沟自然环境背景，发现哈尔木沟的地形地貌和降水条件均有利于泥石流的暴发，受新构造运动与地震影响，沟域内发育大量崩滑体为泥石流的形成提供丰富的松散固体物质。目前沟内由于松散固体物质充足,诱发泥石流灾害的降雨临界值较低，近5年每年均暴发泥石流。针对哈尔木沟的具体情况，提出了拦排结合的治理思路，修建拦挡坝调节泥石流峰值流量，排导槽将泥石流顺利排泄至主河。历经近5个水文年，表明防治工程治理效果良好。

Abstract:

Haermu ravine is located in the middle reaches of Zagunao river and belongs to “5·12” Wenchuan earthquake area, where debris flow rushed down many times in the history and once blocked off Zagunao river in August 1989. By the influence of “5·12” earthquake, the debris flow is with the characteristics of larger scale, higher occurrence frequency and longer active period than before. Based on the analysis on natural environment background of Haermu ravine, it is found that the topography and precipitation conditions of Haermu ravine are conducive to the outbreak of debris flow; by the influence of neotectonics movement and earthquake, large amount of slumped mass developed in ravine domain, which provides a wealth of loose solid material for debris flow. Currently, due to the enough loose solid material and the low rainfall threshold of debris flow, debris flow takes place every year in recent 5 years. According to the specific conditions of Haermu ravine, the disaster control idea of interception combined with drainage was proposed, blocking dam was built to regulate the peak flow of debris flow and drainage canal was utilized to drain the debris flow to the main river. Through nearly 5 hydrologic years, good effects of control engineering are presented.