| Jiangle County is located in the northwest of Fujian Province,southeast the Wuyi Mountains.The landforms is dominated by low mountains and hills,this area has very heavy rainfall,the character of geological disasters is much in type and widespread in distribution,which pose a huge threat to production and life.Based on the field investigation of geological disasters,according to the literature of geological disasters and expert experience,the geological hazard distribution and formation mechanism of Jiangle County were studied,the main conclusions are as follows:(1)The main types of geological disasters in Jiangle County include landslide,unstable slope,collapse,mud-rock flow etc.The total number of geological disaster points is 390,including 301 landslides,accounting for 77.18%of the total;46 unstable slopes,accounting for 11.79%of the total,37 collapses,accounting for 9.49%of the total;5 mud-rock flows,accounted for 1.28%of the total;1 ground subsidence,accounting for 0.26%of the total.The average density of the county geological disaster is 0.17/km2,along the provincial road 204 line,the distribution density of Dayuan Town,Anren Town,Yufang town,Muyuan town,Guangming town,Shuinan town is highest.In time,geological disasters concentrated in heavy rainfall years,mainly during the rainy season.(2)There are 130 geological hazard points with poor stability,accounting for 33.33%of the total number of geological disasters;There are 226 geological hazards with relatively poor stability,accounting for 57.95%of the total number of geological disasters;There are 34 geological hazards with good stability,accounting for 8.72%of the total number of geological disasters.The geological disaster points are mainly based on the poor stability and relatively poor stability.According to the survey and evaluation,since 2002,geological disasters have caused 22 people dead and missing,damaged 1920 rooms,the direct economic loss is 101.36 million;at the same time,geological disasters will threaten the lives and property of 11106 people,property losses estimated at 121.57 million.(3)Jiangle County geological disasters are mainly distributed in the hill tableland of altitude below 500 m,it happen to the zone,in which the natural slope is among 25-45 degrees and the slope height is below 20 m,and the concave slope and the straight hillslope are the most developed.Soil derived from rocks such as granite,sand gravel and sand stone,the thickness is large and the soil is loose,this soil is the most important disaster causing body,the geological disasters generated by it accounted for 92%of the total number of geological disasters in the county.There is a lot of rain and concentrated rainfall in Jiangle County,runoff with strong scouring ability is easy to form,it will erode the foot of the slope,leading to slope instability.Joint and fissure development of rock-soil body is easy to cause deformation of rock-soil body and is beneficial to infiltration and redistribution of precipitation and groundwater,the gravity of rock-soil body itself increases,it is easy to make the weak surface to form a slip band,the slope is much more unstable,leading to geological disasters such as landslide and collapse.In addition,human activities cause natural balance damage of rock-soil body in mountain slopes,it has become another major inducing factor of geological disasters.Among them,the landslide and collapse caused by the steep slope of the slope building is the most important type of geological disasters.(4)According to the types of geological disasters in Jiangle County and development characteristics,distribution and formation mechanism,put forward countermeasures and suggestions from the aspects of the construction of legal system,management mechanism,science popularization,and puts forward some suggestions of monitoring and prevention,biological control,project management,relocation and other measures. |
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