Study On The Mountain Torrent Disasters In Chongqing

Mountain torrent disasters which are caused by high-intensity torrential rain of mountain are natural disasters. There are many mountains in China, the area of mountains account for 69% of the area of whole country, the number of mountain towns' accounts for 50% of the number of towns in China, the population of mountain is more than 20% of the population of China. Because of complicate natural conditions, large population density in mountain area, and neglecting of town planning and mountain torrent disasters controlling during the construction of mountain towns, the event of flash floods will result in a major disaster casualties and huge property losses. According to the geographical environment of Chongqing city , we research on the mountain torrent disasters of Daihu in Jinyun Mountain, Beibei district Chongqing and Bishan country Chongqing, the results show as follow:(1)The risk assessment of mountain torrent disasters is always based on the method of analytical hierarchy process(AHP)-at first we chose and analysis the weights of some factors which will deeply influence with the occurrence of mountain torrent disasters, and then take the reasonable controlling measure to decrease the occurrence probability of mountain torrent disasters, and finally according to combining the conditions of geographical environment and weather in Chongqing, we assess to the risk of mountain torrent disasters. The results show that rainfall is the determinative factor of the occurrence of mountain torrent disasters; we chose other 5 factors such as relative height difference, slope, vegetation, soil and human behavior. These factors' contribution to mountain torrent disasters from highest to lowest as follows: relative height difference>soil>slope>human behavior> vegetation. And then analyses the rainfall, topography and human activity factors' influence on the history of flash floods in Chongqing City.(2) Chongqing is the city in which usually happen mountain torrent disasters, in the city, there are many different scale mountain torrent disasters every year. At the same time, flash floods disaster which leads to huge property losses, accompanied by landslides, debris flow disasters, and the characters of mountain torrent disasters in Chongqing city are seasonality, the mountain torrent disasters always happen in June to August, and also they always happen in the south of Daba Mountain, Qiyao Mountain, and east of Huaying Mountain and the hill area of Qijiang country, at the same time the mountain torrent disasters have strong destructive power and serious harmful endangering. According to the statistical analysis of the loss of disasters in Chongqing,we find thatthe disaster loss trends are increasing year by year. Especially in 1980s the loss of disaster countries is more serious than towns.(3)By combining the contour map of Daihu in Jinyun Mountain, using the Arcview software, building the DEM, we chose the history information of torrential rain in Beibei district, and simulate the water level's rising under the different torrential rain condition, and then confirm the deepness of inundation in Daihu through the weather report, and finally take the precautionary measurement to decrease the loss which is caused by mountain torrent disasters in the watershed.(4)The city construction changes the original ecological environment, and has deep influence to the mountain torrent disasters' happen. We chose the Beibei district and Bishan country as the research area. By combining the contour map of Beibei district, using the Arcview software and hydraulic formula, building the DEM, confirming the relief and catchments area of Beinan Road, we simulate the deepness of inundation and the loss caused by the path of water under the condition of the maximum sixty-minute rainfall intensity and the maximum ten-minute rainfall intensity. Base on collecting the altitude map of Bishan country and the history information of mountain torrent disasters in Bishan, choosing the some of representative contributions in Bishan, simulating the different water level condition and the deepness of inundation of Binan River, we calculate the condition of deepness of inundation in the whole Bishan country, we also find that if the water level of Binan River exceeds the height of river levee, there are large loss in the whole Bishan country.(5)Because of the huge loss which is caused the mountain torrent disasters, we have to take some measurement depended on The Scientific Outlook on Development which means putting people first and aiming at comprehensive, coordinated and sustainable development. We also have to ascertain the whole idea of controlling the mountain torrent disasters under analyzing the condition of Chongqing and the character of mountain torrent disasters. The measurement of controlling mountain torrent disasters should depend on the prevention and treatment and also put the prevention and treatment together, it also should depend on the non-engineering measures and engineering measures, and put both of them together. At this stage the primary objective is to reduce casualties.