The Geological Hazards Assessment Of Yilan Navigation And Hydropower Project

With the economic development of the Songhua River basin, industrial and living water consumption increased year by year, resulting the water level of the lower reaches of the Songhua River has been lowered gradually,which has affected the normal navigation. The Sanxing shoal located between Tonghe to Yilan route ShaHeZi and 41km to Yilan is facing increasingly prominent navigation obstacle problems. For years, the average runoff volume has declined from 488×108m3 to 342×108m3. The river can not meet the shipping requirement because of the scattered river, hard rocks and steep river gradient. Impacted by the reduced water volume, the navagation of the SongHua river is facing the risks of partly or completely navagation interrupt. Thus, following the construction of the Dadingzi mountain navigation and hydropower project, another project is being planned and constructed at Yilan,in order to improve the navigation conditions of Songhua River. As the dam site and reservoir area covers an area of large, complex terrain, so in the pre-construction risk assessment of geological hazards of great significance.This paper, taking the Yilan Navigation and Hydropower Project as the research background, more in-depth analyzed the geological status within the construction site and geological disasters possibly caused by the construction project,identified the types,distribution,characteristics,trends of the disters,predicted and assessed the degree of hazard and risks. Moreover, the paper provided reliable information of disaster prevention and control of geological disasters for the construction project. This paper made the following findings:1. By comparative analyzing the geological disasters within construction site of Yilan Navigation and Hydropower Project, the paper comprehensively assessed the degree of geological disasters,divided the hazard level,illustrated main types and degree of the disasters,and identified the harm of the riverbed stability and permeability caused by the uplift of new tectonic movement, which should be focused on defense.2. The paper assessed the degree of geological disasters hazard caused by the construction, in conjuntion with the built-up areas of regional geological conditions and historical earthquake levels,and predicted a increasing possibility of geological disasters. On this basis, the paper also proposed disaster prevention measures and suggestions and suitable decision-making for building sites.