| China is a geological disaster-prone countries,especially in the southwestern region,because of its geological conditions and geographical environment complex and so on,making geological disasters occur frequently.Especially in the recent period,the acceleration of the urbanization process,human activity is increasingly strong,once encountered heavy rainfall,induced geological disasters will be a serious threat to the people's property and life safety.More and more people are aware of the importance of mitigating and preventing the development of geological disasters,and it is urgent to carry out risk assessment of geological hazards so that the areas with high risk can be effectively controlled and managed to reduce the loss of people's property.Therefore,how to carry out risk assessment of geological disasters in the region is a major issue that must be faced in urban development and disaster prevention and mitigation planning.Guizhou Province is one of the most serious areas of debris flow disaster in China.As the debris flow in Guizhou Province is mostly dangerous for hydraulic debris flow,it is potentially dangerous.If it is not timely to take precautionary measures,in the case of extreme weather conditions(such as heavy rainfall)There is a risk of debris flow where the outbreak may be debris flow,causing disasters.It is in this context,this paper to Weili County,Guizhou Province,two Tong River Basin,for example,relying on the Guizhou Provincial Department of Land and Resources major projects-"Guizhou key geological hazard risk assessment and control demonstration" to fully collect the existing basis Data,combined with high-resolution remote sensing images,the high-resolution remote sensing interpretation of the landslide and debris flow in the monkey town of the Ertang River Basin,and the field investigation and verification to determine the final disaster.The method of quantitative risk assessment of debris flow in watershed is studied by using GIS technology and mathematical model.The purpose of this paper is to give the local land sector planning and construction and disaster prevention and mitigation to provide rationalization of the proposal,the main conclusions are the following:1?The distribution characteristics of landslide,debris flow and disaster-bearing body in the basin were analyzed statistically:Based on the high-resolution remote sensing image and 1: 10000 base data,the real three-dimensional scene of the basin is constructed.The landslide,debris flow and the land,road and land type in the monkey town of Ertang River Basin High-precision remote sensing interpretation and field investigation and verification,the establishment of the study area of geological disasters and disaster-bearing body space database.And the types and characteristics of the disaster-bearing bodies were summarized.These underlying data provide important support for subsequent risk assessment.2?The risk assessment of debris flow disaster in small watershed was completedEvaluation of Debris Flow Hazard in Small Watershed According to the characteristics of debris flow development in this study area,the state factors influencing the occurrence and development of debris flow source are selected(Soil erosion modulus,debris flow out of the largest).And topography and geomorphic factors(watershed height difference,gully density,formation area average slope,main channel longitudinal slope,basin area),As a debris flow sensitivity evaluation factor,First,the soil erosion modulus of the basin is obtained by using GIS technology,and the maximum source is obtained according to the erosion modulus.Finally,the sensitivity of debris flow in the study area is obtained by combining GIS technology with fuzzy mathematics.Combined with the risk assessment model,calculate the risk of each debris flow,the formation of the study area of debris flow risk assessment map,lay the foundation for the subsequent quantitative risk assessment.3?Carried out a small watershed debris flow disaster vulnerability assessmentFirst of all,according to the natural environment of the study area and the field investigation,combined with the previous study of vulnerability,this paper evaluates the vulnerability of the study area from four aspects: material vulnerability,social vulnerability,Environmental vulnerability,economic vulnerability.And the damage coefficient of the disaster-bearing body and the threat coefficient of the danger zone are introduced.The vulnerability assessment model is built on the disaster-bearing area within the threat area,and the vulnerability of each debris flow is calculated,Evaluation of Quantitative Vulnerability of Debris Flow in Monkey Town.In order to evaluate the maximum threat range of debris flow,this paper chooses ASC model to calculate the maximum outflow of each ditch,according to the characteristics of the hazard.First,combining the topography and geomorphology of karst area and selecting the appropriate evaluation model And the slope and buffer analysis were carried out by using GIS technology to determine the maximum threat range of debris flow according to the two main parameters of the horizontal gradient and the horizontal distance from the main channel in the lower reaches of the basin.Based on the results of the vulnerability assessment,the vulnerability value of the debris flow threat is calculated,and the volcanic erosive vulnerability evaluation map of the Ertang Monkey Field is established.4?The quantitative risk assessment and mapping of debris flow in small watershed were completedThe quantitative risk assessment of debris flow in small watershed is the result of comprehensive analysis of the occurrence of debris flow disaster in the basin and the loss caused by the factors.Based on the results of the evaluation of debris flow risk and the evaluation of vulnerability,the quantitative risk assessment model is constructed and the risk of soil debris flow is calculated by using GIS technology.It represents the degree of risk of debris flow in this area.The higher the value,the greater the risk.According to the debris flow risk and vulnerability classification criteria,the risk is divided into four grades: 0 ~ 0.16 for the low risk,0.16 ~ 0.36 for the moderate risk,0.36 ~ 0.64 for the high risk,0.64 ~ l is extremely high Risk,to complete the small watershed debris flow quantitative risk assessment and zoning.From the statistics on the quantitative risk assessment of the debris flow in the study area and the regional risk zoning of the debris flow,it is found that there are 1 high-risk debris flow,which is the Pingdong Village,which has a large number of houses,densely populated and soil erosion,Terrain and geomorphological conditions are very conducive to the outbreak of debris flow;high-risk debris flow has five,for the hole through the village ditch,hair village,Wu Jiapao ditch,sand on the village and the village of Changgong Village 1 #(# 2,# 6,# 7,# 8 ditch)and the sand ditch,the rest of the low risk of debris flow,a total of 5,for the Ming Dongcun ditch,through the village of three groups of ditch,luo Mo Sha Village under the village of long red village(# 4,# 5)ditch. |
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