The Ecological Risk Management Of The Water-level-fluctuating Zone In Chongqing Area Of The Three Gorges Reservoir

The Yangtze River three gorges project is the most magnificent project in the world.When it is finished,according the existing planning of its storing clear water and releasing sediment operation mode, the water will maintain in 175m in winter and maintain in 145m in summer.Then a fluctuating zone, with a straight fall amounting to 30 meters will be formed in areas along the river.The Water-Level-Fluctuating Zone as a wetland ecosystem is a zone where water ecological and terrestrial ecosystem have alternating control or interactions.This system is vulnerable to natural factors and human factors, so it is a fragile ecosystem.As a wetland ecosystem, the WLFZ has both external risks and internal risks. Internal system risks can be divided into two kinds:natural risk and human risk. Natural ecological risks are mainly caused by the variation of natural ecological system structure and function of the harm events and phenomena, such as geological disasters including drought, flood, drought-relief meteorological disasters, collapse, landslides and debris flows. The human ecological risks are some activities that can harm or interfere the ecological system, such as crops risk, livestock breeding risk, agriculture risk, solid waste, entertainment risk and engineering construction risk. External risks include the organization and management risk, market risk and the national policy risk to coordinate different stakeholders'interest.We usually classify the WLFZ according to human activity intensity as the main factor to. At the same time, we use and an index system consisted of slope of the land, exposed land matrix, the type of the land, time of inundated land and land to analysis of ecological risk distribution of different drawdown areas. The urban-WLFZ area is mainly to reduce the industrial solid waste pollution and pollution source, prevent floods. The rural-WLFZ is mainly to avoid crops risk and risk of aquaculture, prevent agricultural non-point source pollution and soil erosion. The WLFZ of the tourist attraction type is mainly to averse human risk, protect tourism resources. The WLFZ of the Gorge type is mainly to reduce the geological disaster risk.The structure,function and risk of the WLFZ is different in different sections. According to the different ecological system function and characteristics such as the level of productivity, stability of reservoir banks and tourism value, we can propose four patterns to avoid risks. The four models are Urban Flood sewage-type model, the rural-based model of anti-pollution control soil erosion, nature conservation-type model of wetland ecosystems and cultural tourism-based mode of governance-based model of restoration.Finally, this paper proposes different measures to avoid the ecological risk from the aspects of industry, structure and function of the wetland ecosystem.