| Even though society makes progress continually, the environment of living is increasingly vulnerable. In the background of global warming, natural disasters, such as earthquake, floods, mudslides and droughts, still occur. As a result of that, it threats people’s lives and property safety, social stability and regional sustainable development seriously. Torrential rain disaster is one of the common natural disasters of China. It can cause a variety of secondary disasters including floods and waterlogged disaster, and has become the focus of research at home and abroad. Due to the monsoon climate and blocking effect of the Qinling Mountains, heavy rains occur frequently and cause torrential rain disasters at Qinling. As a result, people’s lives and property are harmed greatly. At present, the research of torrential rain disaster at southern and northern area of Qinling Mountains is less. The study provides a theoretical basis and policy support for the regional ecological environment, sustainable economic development and government decision-making through the study of torrential rain disaster risk assessment and it’s situation of time and geographical.Statistical data of annual precipitation at eleven meteorological stations from1955to2012, statistical data of daily precipitation at eleven meteorological stations from1967to2012, statistical data of daily precipitation at five meteorological stations from2004to2012and socio-economic data of sixteen counties and cities in southern and northern area of Qinling Mountain are collected systematically in this study. Underuse the software of SPSS、EXCEL、MATLAB、ArcGIS, according to the Wavelet Analysis and Kriging this paper analyzes torrential rain situation of time and geographical at southern and northern area of Qinling Mountains. According to theory of regional disaster system, theory of natural disaster risk assessment and Decision Analysis of AHP, torrential rain disaster risk index system is created from factors leading to disasters, environment promoting disasters, hazard-affected bodies and capacity of disaster prevention and mitigation four aspects. Further, the study uses Analytic Hierarchy Process to calculate the weight of each index value, and uses the weighted comprehensive evaluation method to establish a torrential rain disaster risk assessment model. Furthermore, the torrential rain disaster risk levels of sixteen counties and cities in southern and northern area of Qinling Mountains are determined using ArcGIS software Kriging and grid calculators. After the study, the main conclusions are:(1) Situation of time and geographical of annual precipitation at southern and northern area of Qinling Mountains. Over the years the average annual precipitation of Qinling mountains rea is770.1mm. And it has a fluctuating downward trend, with the phenomena that the annual maximum precipitation occurred in1983, the minimum precipitation occurred in1997, both the ratio was2.32. We regard Qinling Mountains region in the late1950s,1960s,1980s and early21st century as the rainy period in the1970s, and the1990s as drier period. Average annual precipitation exist significant difference in the space. Largest annual precipitation occurred in Foping and Shiquan, and the least in Xi’an and Wugong. The entire region showed a distribution that precipitation in southern part was less than that in the north, west was more than that in the east. Regional precipitation had a21-year long cycle and short cycles of seven years and four years.(2) Situation of time and geographical of torrential rain at southern and northern area of Qinling Mountains. The occurrence of torrential rain had obvious seasonal variation, and the number of days having torrential rain all the year was unimodal distribution. The earliest torrential rain occurred in April, at the latest at the end of November, and the majority in July that accounting for38.1%of the total precipitation. The total number of days having torrential rain from June to September accounted90.8%of that days all the year. The average precipitation of storm did not change significantly over the years. The Inter-annual variation of torrential rain days changed obviously. The time in the early1980s and the21st century was the storm-prone period, and that the early1990s was a period when had least torrential rains. The torrential rain increased significantly and daily maximum precipitation achieved the peak since the21st century.From the space point of view, the storm precipitation of south Qinling Mountains is larger than the north, and the west is larger than east. The total days of torrential rain and average storm precipitation in the south Qinling Mountains is more than that in the north. The difference of the average preciation among these areas is not significant, while the difference of days having torrential rain is so significant. The total days about torrential rain of Shiquan, Hanzhong, Foping, Ankang, Langao and Shangnan are above80days. The total days of torrential rain in Shiquan is4.125times more than that in Xi’an. Torrential rain occurred mainly in the areas in research are Lueyang, Foping, Shiquan, Langao and Hanzhong, which the torrential rain counts in these areas are54.12%of the total. Days having torrential rain presented a21to24and seven years of quasi-period in time. Daily maximum precipitation was the most prominent in4and7-years quasi-period. And days having torrential rain and daily maximum precipitation had about a7and20-years quasi-period.(3) Analyze the factors of the torrential rain disaster. This study analyzes the risk of the torrential rain disaster from4aspects which are the dangerousness of the factors leading to disasters, the susceptibility of the environment promoting disasters, the fragility of the hazard-affected bodies and the capacity of prevention and reduction. From the factors leading to disasters aspect, Hanzhong, Shiquan, Ankang and Shangnan are in the high risk area. From environment promoting disasters aspect, Hanzhong, Ankang,Mei county, Wugong and Hu county are in the high susceptible area. From the hazard-affected bodies aspect, Hangzhong, Wugong and Xi’an are among the high fragile area. From the capacity of prevention and reduction aspect, Baoji and Xi’an are among the high ability of disaster prevention area.From the space point of view, the storm precipitation of south Qinling Mountains is larger than the north, and the west is larger than east. The total days of torrential rain and average storm precipitation in the south Qinling Mountains is more than that in the north. Shiquan, Hanzhong, Foping and Ankang are at the high risk of torrential rain disaster areas. The total days of torrential rain in Shiquan is4.125times more than that in Xi’an. Torrential rain occurred mainly in the areas in research are Shiquan, Foping, Hanzhong and Ankang, which the torrential rain days in these areas are71.7%of the total days.(4) Torrential rain disaster risk assessment. The areas having high-risk of torrential rain disaster are mainly distributed in the south of Qinling Mountains. In these areas the annual torrential rain days and annual precipitation are higher and torrential rain occurs frequently, so it is dangerous. Also the terrain、environment etc. can lead to disaster while the average GDP is not high in these areas. The high risk areas of torrential rain disaster among the research areas are Hanzhong, Ankang, Shiquan and Shangnan. The low risk areas of torrential rain disaster are Baoji and Shangluo.Hanzhong is at a high value area in factors leading to disasters, environment promoting disasters and hazard-affected bodies aspects while at the second-high value area in capacity of prevention and reduction aspect. As the result of that, the synthetic torrential rian disaster risk index of Hanzhong is in the high risk area. From factors leading to disasters aspect, Ankang,Shiquan and Shangnan are at a high value area and at the environment promoting disasters acspect, they belongs to a high sensitive area while at hazard-affected bodies they are individually among second-highest fragile area and medium vulnerable area. And at the capacity of prevention and reduction aspect they are among low ability of disaster prevention area. And then we can conclude that the risk of torrential rian disasters in these areas are high.Because of the factors leading to disasters in Baoji is low, it belongs to a second-highest sensitive area at environment promoting disasters aspect, is in medium fragile area at the fragile of hazard-affected bodies aspect. While it is high at capacity of prevention and reduction aspect.Then we can know that the risk of torrential rian disasters in Baoji is low. Shangluo is in low dangerous area at the factors leading to disasters aspect, belongs to a second-highest risk area at environment promoting disasters aspect, is in less fragile area at the fragile of hazard-affected bodies aspect, and is low at capacity of prevention and reduction aspect. Then we can conclude that the risk of torrential rian in Shangluo is low.(5) According to the research of torrential rain disaster around the Southern and Northern Area of Qinling Mountains, this study gives some suggestions as follows to prevent disasters and reduce damages: Strengthen the construction of disaster prevention and reduction engineering; Strengthen the monitoring of hydrological factors and improve the accuracy of the torrential rain disaster forecast; Improve the awareness of disaster prevention and reduction of the public; Improve the emergency mechanism; Do the best of soil and water conservation works. |
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