Slope Disasters Susceptibility Assessment In Longxi Section Of Weihe River Upstream

Longxi section of Weihe river upstream west is located in the loess plateau typical district,adjacent to the fault zone along the northern edge of West Qinling,influenced by tectonic activity,strong development of geological disasters,especially in the Weihe river on both sides of the slope,are unstable region and highly unstable region,the Weihe river ? and ? level terrace is densely populated,human production activities is relatively concentrated area,the geological disaster threat seriously.Therefore,on the basis of collecting data and understanding the basic situation of study area,the basic situation of geological disasters in the study area was identified by means of remote sensing interpretation and field geological survey.The influencing factors of various types of disasters were studied in detail,and the study area were divided and detailed comparative studies were conducted.The main conclusions are as follows:(1)The main geological hazards in the area are unstable slopes,followed by landslides and collapses.The unstable slope is mainly linear slope,and the soil slope is the main form.Small loess landslide is the main type of landslide,and about 1/3 loess-red bed landslide is developed.Most of the collapses occurred in local steep sections,which were obviously controlled by loess joints.(2)Slope angle 15~35°,elevation 1700~2200m,south and southwest slope direction,relief amplitude 90~150m,Quaternary and Paleogene strata,distance to loess-red bed unconformity surfaces within 500 m,Normalized Difference Vegetation Index of 0.15~0.3,distance to river within 400 m are disaster-prone areas.There are certain similarities and differences in the sensitivity of different types of disasters to various factors.On the whole,the sensitivity of landslides to various factors is the highest,followed by unstable slopes,and the collapse.In addition,the sensitivity of disasters to vegetation,landform,water system,geological conditions and human activities is reduced successively.(3)According to the characteristics of the study area,the loess-red bed unconformity surfaces distance is put forward as the geological condition,and through the analysis of the influencing factors and the susceptibility evaluation,it is shown that the loess-red layer distance as the geological condition is effective and feasible to study the related geological hazards,and it is better than the traditional stratigraphic lithology.(4)According to the disaster development pattern,the study area was divided into five susceptibility: very low,low,moderate,high,very high,respectively,accounting for 16%?22%?20%?23%?20% of the area in the study area.That very low and low area is mainly distributed in the southern vegetation good area,moderate area mainly distributed in area which distance to river and loess-red layer has a certain distance,high and very high area prone to high altitude and the nearby area of loess-red layer,is affected seriously by the human engineering activity.There is a good correspondence between partition results and disaster distribution.