FENG Qiang,TANG Chuan,CHEN Ming,et al.Field Investigation and Research on Debris Flow on August 20,2019 in Mianshi Town,Epicenter of Wenchuan Earthquake[J].Journal of Disaster Prevention and Mitigation Engineering,2022,42(01):51-59.
FENG Qiang,TANG Chuan,CHEN Ming,et al.Field Investigation and Research on Debris Flow on August 20,2019 in Mianshi Town,Epicenter of Wenchuan Earthquake[J].Journal of Disaster Prevention and Mitigation Engineering,2022,42(01):51-59. DOI: 10.13409/j.cnki.jdpme.20210220002.
Field Investigation and Research on Debris Flow on August 20,2019 in Mianshi Town,Epicenter of Wenchuan Earthquake
On August 20, 2019, a large debris flow occurred in Dengxi valley, Miansi Town, Wenchuan County.As a result, a large number of houses, national highways and expressways were washed out at the mouth of the ditch, and traffic was interrupted for months. At the same time, a large amount of material rushed out blocked the main channel of Minjiang River, causing the channel of Minjiang River to be diverted to the left bank and the water level to rise, forming a chain disaster. Based on the formation conditions, disaster-causing characteristics of the debris flow in Dengxi valley, as well as the field investigation and remote sensing image interpretation before and after the debris flow event, the bulk density and dynamic characteristics of the debris flow, such as velocity, discharge and debris flow outflow, were calculated by using the weight method and morphological investigation method The results show that the Dengxi valley debris flow is the result of the combined action of many factors, such as short duration heavy rainfall, favorable topographic conditions, abundant provenance produced by earthquake and strong erosion of the channel. The disaster pattern is summarized as a movement process as follows :rapid confluence of rainfall-initiation-formation of debris flow by materials of the vally-erosion of materials at the bottom and both sides of the gully-collapse of bank slope and blockage and outburst- the scale of the debris flow becomes large and rushed out. The image interpretation before and after the debris flow event showed that the provenance of slope and channel evolved significantly with time, and the provenance in the basin was still rich.The activity of debris flow is still high in the Wenchuan earthquake area ten years after the earthquake. Although more than 10 years have passed since the Wenchuan earthquake, the activity of debris flow is still relatively high. Therefore, the detailed investigation and analysis of the debris flow activity in Dengxi valley are carried out in order to strengthen the further understanding of the characteristics of debris flow in the medium and long term after the earthquake in the strong earthquake area.
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