Study on the risk of debris flow in Maoshangou, Yanqing District, Beijing

This paper is the result of debris flow hazard study.[Objective]The debris flow, because of its wide range, rapid disaster and great harm, has caused damage to the basic engineering facilities in the mountain area, and seriously hindered the regional economic development. In recent years, geological disasters have occurred frequently in the mountainous areas of Beijing.Yanqing District, as the ecological conservation area of Beijing, has many tourist attractions, but there are also many hidden dangers of debris flow. [Methods]In order to reduce the potential threat of debris flow, it is very important to study related debris flow in Yanqing District.In this paper, the debris flow ditch in Chashikou village of Yanqing District is taken as the research object to analyze and forecast the risk. [Results]The results show that loose deposits of Maoshangou can be categorized into three types:alluvial and diluvial deposits, residual-slope deposits, and artificial deposits, with a dynamic reserve of 9.9×10⁴ m³.From the peak flow value and the total amounts of solids washed out by the primary debris flow, it can be determined that the size of this debris flow is medium. By varying rainstorm frequencies (10-, 20-, 50-, 100-year rainfall events), the respective hazardous areas are measured to be 0.004 4, 0.005 1, 0.005 9, and 0.006 8 km².The stage of debris flow development is considered to be a recession period. [Conclusions]After thorough discussions, it was found that the chances of the debris flow gully erupting into a medium-sized debris flow are high, which will pose a hazard to the residents of the downstream roads and villages. The detailed study of this ditch not only helps to deeply understand the mechanism, dynamic characteristics and development trend of the debris flow in this region, but also provides a reference for the study of debris flow and disaster prevention and control of the single ditch under similar geological conditions.