Assessment Of Debris Flow Risk In County Scale Based On GIS

The geological disasters are extremely serious in our country, and the debris flow hasbeen seriously affecting the normal life and production of people in the mountainous areas.Once the debris flow breaks out, a large amount of people would be threatened and it wouldcause great casualties and economic losses, which restrict the development of the economy.So it is especially important to reduce and prevent the debris flow. It is necessary to intensifythe study, evaluation, management of reducing disaster and prediction of the debris flowdisaster. At the same time, the organiation and implement of the economic, effective andreasonable preventive projects are very significant. The primary task is to understand andevaluate the possibility, hazard, scope and degree of the debris flow disaster. Reflecting thecurrent situation and development tendency of the debris flow rapidly can provide animportant scientific ground for guiding the decision of the prevention, relief and reduction ofthe debris flow disaster.Chencang District in Baoji city is located in the west of the central Shaanxi plain which isthe center of torrential rain. The rain days are common in this area and the activity of theunderground water is intense，which cause the geological disasters as debris flow occur easily.The debris flow affects the safety of people’s normal life and production. In this paper, thecharacteristic and class of the debris flow in Chencang District were stated. And theevaluation principle of the debris flow danger was established, and then the danger evaluationsystem of the debris flow was set up by the analysis of the formation conditions. The analytichierarchy process and information content method mathematical model were used to calculatethe weight and information content of each evaluation factor respectively, and the evaluationresult would be obtained combining the ArcGIS. Finally the comprehensive evaluation mapwas drawn through the comparative analysis of these two kinds of evaluation results.Form the result of analytic hierarchy process, we can know that the extremely highdanger area majorly lies in the area of Guo Town—Yangping Town, Xiangquan Bason and Wei River fault zone. The high danger area lies in both shores of the Wei River of FenggelingTown—Tuoshi Town—Huding Town—Pingtou Town, the loess tableland of Jiacun—QianheTown, the loess tableland of Guo Town—Yangping Town and the east side of Qian River. Themedium danger area lies in the loess ridge and hills of XinjieTown—Qiao Town and the areaof Jingling River. The low danger area lies in the south of Pingtou Town, Tongdong Riverbasin in the north of Fengge Town and Jiachenggou in the north of Tuobei Town. Theextremely low danger area majorly lies in the western mountains area of Qinling Mountainsand Longshan mountains.The result of the information content method shows that the extremely high danger areamajorly lies in the loess tableland of Guo Town—Yangping Town, the east of Yangquan basonand the Wei River sides of Pingtou town. The high danger area lies in the loess ridge and hillsof Xinjie Town—Qiao Town, Jiancun—Qianhe Town and Qiangquan bason. The mediumdanger area lies in the west area of Pingtou Town, Xinjie Town—Xiangong Town. The lowdanger area lies in Tongdong River basin in the north of Fenggeling Town, the north slope ofthe south of Qingling and the north mountains area of Chencang District. The extremely lowdanger area lies in Qingling mountais and Longshan mountains area.Comprehensively considering these two kinds of evaluation results mentioned above thecomprehensive evaluation map of the danger of debris flow in Chencang District was drawnand obtained the comprehensive evaluation results of debris flow danger in town scale. Theresults showed that the high danger area mainly contains of Qianhe—Yangping CountyDistrict, Chisha—Xiangquan District, Wei River valley of Fenggeling Town—Pingtou Townang Xinjie—Qiao Town District. And at finally, the comprehensive measures of theprevention and reduction of the disaster were put forward on the basis of the study of thespecific situation of geological disaster as debris flow in the study area.