1.长安大学;2.青海省地质环境监测总站
国家自然科学基金；科技部重点基础研究计划项目
- MA Zhiliang 1
- ZHUANG Jianqi 1
- WU Jing 2
- CAO Yanbo 1
- CHEN Shengyin 1
- CHANG Lei 1
- ZHAN Jiewei 1
- MA Penghui 1
- KONG Jiaxu 1
National Natural Science Foundation of China; Key Basic Research Program of the Ministry of Science and Technology
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[目的]短时间的极强降雨在山区诱发极低频泥石流，对山区人居安全和生态环境带来严重威胁。本文以2023年“8.11”鸡窝子山洪泥石流为研究对象，对该山洪泥石流的特征和成因进行分析，并进行危险性评价。[方法]通过野外调查、数值模拟等手段，采用实际降水频率，开展了2023年“8.11”鸡窝子山洪泥石流形成过程反演。[结果]（1）强降雨快速汇集形成洪流，导致上游沟道松散物质被揭底侵蚀，形成“消防水管”效应，暴发山洪泥石流，并借助陡峭地形对全流域沟道进行侵蚀，大量堆积物和巨大冲击力在下游扩散开来形成堆积扇，并堵塞河道。（2）在实际降雨频率下模拟得出，泥石流全流域淤积深度在0.04~5.63 m之间，最大流速7.43 m/s，堆积扇面积1.91×104 m2，一次性冲出量为78271 m3。（3）基于流速、泥深和危害范围，给出了高、中、低三个危险区域，堆积扇西侧区域地势较高为低危险区，占堆积扇面积约10%，中间区域和堆积边缘至公路区域为中危险区，该类面积占62%，堆积扇东南和西南区域为高危险区，该类面积占28%。[结论]2023年“8.11”鸡窝子山洪泥石流是一次典型由极端短时强降雨诱发的低频山洪泥石流灾害，研究揭示了低频泥石流的触发机制和运动特征，FLO-2D模型有效模拟了泥石流的运动和沉积过程，并确定了泥石流的危险范围。研究成果可为秦岭山区类似低频泥石流的防灾减灾提供参考。
[Objective] Extremely heavy rainfall in a short time can induce extremely low frequency debris flow in mountain area, which brings serious threat to human security and ecological environment in mountain area. In this paper, the characteristics and causes of the 2023“8.11” Jiwozi flash flood and debris flow are analyzed, and its risk is evaluated. [Methods] The formation process of the “8.11” 2023 Jiwozi flash flood and debris flow was retrieved by means of field investigation, numerical simulation and actual precipitation frequency. [Results] The results are as follows: (1) The rapid confluence of extremely short duration and strong rainfall resulted in a flood, which resulted in the erosion of loose materials in the gully, formed the effect of “Fire hose”, and caused a small-scale collapse of the mountain, flash flood debris flow is formed in the gully, and the gully is eroded by the help of steep terrain. (2) Under the actual rainfall frequency, the final depth of debris flow is between 0.04 m and 5.63 m, the maximum velocity is 7.43 m/s, and the one-time discharge is 78271 m3. (3) Based on the velocity of flow, depth of mud and hazard range, three high, middle and low risk areas are given, and the high terrain area on the west side of the accumulation fan is the low risk area, which accounts for about 10% of the accumulation fan area, the middle area and the area from the edge of the pile to the road are medium-risk areas, accounting for 62% of the area, while the areas of the south-east and south-west of the pile fan are high-risk areas, accounting for 28% of the area. The research results can provide scientific reference for the risk control of extremely low frequency flash floods and debris flows in the mountainous areas of Qinling Mountains. [Conclusion] The 2023“8.11” Jiwozi flash flood and debris flow is a typical low-frequency flash flood and debris flow disaster induced by extremely short-term heavy rainfall, and the FLO-2D model effectively simulates the movement and sedimentation process of the debris flow, and determines the danger range of the debris flow. The research results can provide a reference for disaster prevention and mitigation of similar low-frequency debris flows in Qinling Mountains.
