【摘要】 针对2017年8月8日九寨沟地震可能引发更多泥石流灾害及其防治的问题,基于2018年6月25日四川九寨沟县西番沟泥石流灾害的现场调查和物源特征分析获得泥石流的性质及其发育成因,并提出防治对策。研究发现2018年6月25日西番沟泥石流为50年一遇的中等规模低频稀性泥石流,其流量为80 m~3/s,一次泥石流总量约1. 5万～2万m~3,流速约5. 5～6 m/s;其发育的成因之一是2017年8月8日四川省九寨沟县发生7. 0级地震引发高山区松散固体物质增加所致。调查显示地震引发可能参与泥石流运动的物源数量和动储量分别为78. 81×10~4m~3、23. 64×10~4m~3。由于流域内还存在大量的松散物源,泥石流还可能在进一步的降水作用下发生,今后的防灾减灾宜采用工程措施和群测群防措施。更多还原

【Abstract】 On August 8,2017,a magnitude 7. 0 earthquake happened in Jiuzhaigou county,Sichuan Province,China. This event had the potential to cause debris flows and pose significant challenges for disaster prevention and mitigation. Subsequently,a debris flow event occurred in Xifangou,Jiuzhaigou county on June 25,2018. The characteristics and causes of this debris flow were investigated in detail,in order to assess the potential hazards created by earthquakes like that of August 8 th,2017 and to develop countermeasures. A thorough analysis of the study area suggested key parameters regarding debris flow movement and frequency. The analysis showed that the2018 debris flow was a medium-scale,low-frequency,dilute debris flow that occurred only once in 50 years. The discharge volume,total volume and velocity of this debris flow were 80 m3/s,1. 5 × 104～ 2 × 104 m3 and 5. 5 ～6 m/s,respectively. A comprehensive analysis established the causes of the debris flow. Due to the impact of the2017 earthquake,the volume of loose solid materials sharply increased,and the critical rainfall amount that can trigger a debris flow was therefore greatly decreased. A calculation model described in this paper was used to compute the total volume of loose solid materials and dynamic reserves in the study area. These were 78. 81 ×104 m3 and 23. 64 × 104 m3,respectively. Following further investigations we found that abundant loose solid material still existed in Xifangou basin. If heavy rainfall were to occur in this area,more debris flows can be triggered in the future. Given the features of the basin and local meteorological conditions,we have proposed the adoption of engineering and non-engineering( public participatory monitoring and warning system) measures to prevent future disasters and reduce potential negative impacts,and a successful implementation of such measures in the study area can provide a reference for prevention and mitigation of debris flow disasters after earthquake in other regions.更多还原