Geological Hazards In The Small Watershed Of Longxi River In Ya'An City Prevention And Control System And Effect Evaluation

"4.20" Lushan earthquake of Yaan city geological environment caused serious damage,caused the secondary geological disasters (landslide, collapse, debris flow, especially in the aftershock, rainfall, such as the role of the secondary disaster is frequent, urban stormwater disaster recovery and reconstruction work to bring serious harm.Ya'an Yucheng District, located in the Minjiang River, Qingyi River area development,Zhougong River, Longxi River and other rivers, many other tributaries, water development.Yucheng District is located in the "4.20" earthquake disaster area, serious earthquake disasters, geological hazards, mainly distributed in the Longxi River Basin, the geological condition is complex, will be the combined effects of disaster heavy disaster area and geological disaster prone areas, river erosion cutting strong, relatively steep terrain, the border area, the dew loose weak of tertiary and Quaternary strata, lithology, geological structure is complex, coupled with the "5.12", "4.20" two earthquakes and earthquake several strong rainfall, territory of geological hazards are well developed, hazard is more serious.Longxi River Watershed in 50 potential points of geological disasters in the total threat households 1961 people in 373 households, property 9655 million yuan; for post disaster reconstruction village inhabited threat households 220 households 720 people, property of 44 million yuan; Longxi River town slope threat households 265 households in 764, total assets of 7000 million yuan, comprehensive geological disaster prevention project investment estimation for 21055 million yuan, through the comprehensive prevention and control, can effectively protect the geological hazard area people's life and property safety, the prevention and control of capital investment than protection of assets. Therefore, on geological disasters in Longxi and small watershed were comprehensive prevention and control is extremely necessary and urgent. And the comprehensive treatment project has certain economic benefits. More important is, through the implementation of comprehensive prevention and control projects can improve the geological disaster prevention and treatment ability, and restoration and reconstruction to lay a good foundation for the town, for rain in the northern part of the city's tourism development and industrial development to provide a safe environment, which will also bring greater indirect benefits.This research is based on the "4.20" earthquake geological disaster emergency investigation and "7.8 flood" geological disaster emergency investigation on the point of geological disasters threatening the safety of the lives and property of the hidden form to small range of Longxi River Basin due to natural factors as the work object, reasonably determine the scope of work of comprehensive prevention and control of geological disasters in Longxi river small watershed, the development characteristics of comprehensive investigation or review of existing or new geological disaster point, distribution and type of the existing hazard point scale, deformation, stability, damage characteristics, in order to ensure the safety of life and property as the primary goal, to ensure both economic and social development space in the region, the value of land use and ecological environment.Protection,summed up the suggestions of integrated watershed management measures,the implementation, achieve the effect after the implementation, so as to extract a small stream Method and system for comprehensive management of geological hazards in the area.