The Cause Analysis And Countermeasures Research Of Eutrophication For The Waihu Reservoir And Jinkengling Reservoir

Since the two reservoirs of Waihu and Jingkengling in Pujiang Country put into operation,they have played a good role in farmland irrigation and drinking water supply,combined with flood prevention,power generation,farming and so on comprehensive utilization.But in recent years,because of life sewage,chemical fertilizers and pesticides used in agriculture and other many factors,the reservoir water has been polluted and the algae bloom has occurred frequently.This is a serious security problem to countryside potable water and city water supply for Pujiang Country and buries unsafe hidden dangers to the villagers.To implement the Central and State Council’s spirit of "consolidating and promoting rural areas’ safe drinking water",to ensure the safety of rural water supply in Pujiang County,to ensure the long-term benefit of the rural drinking water project,this paper monitors and analyzes the current situation of water quality for these two reservoirs and finds the exterior and interior pollution source by field survey and analyses,and analyzes the causes of water eutrophication.Then the paper puts forward effective comprehensive control and rectification measures which can decrease the influence of pollution on water quality and provide a reference for local government when they carry out human settlement environment management work.In this paper,the main study conclusions are as follows:1.From the analysis of current situation of water quality for Waihu and Jingkengling reservoirs,in addition to the total nitrogen and phosphorus,other water quality indexes are better and can satisfy a primary protection standard of centralized drinking water source.Using single index method,comprehensively weighted scoring method and trophic status index method to evaluate the Eutrophication level for these two reservoirs,the result showed that they are both medium eutrophic type.Compared to the monitoring data of eutrophication in some domestic reservoirs when they occur water bloom,the water quality index of Waihu and Jingkengling reservoirs has reached or exceeded the eutrophication control standard,and therefore they have potential crisis of a large outbreak of blue-green algae.2.Analyzing the extraneous pollution source of these two reservoirs,the major sources of nitrogen are from point pollution of household garbage and non-point pollution of chemical fertilizer,and the main sources of phosphorus are from point pollution of livestock and poultry farming and non-point pollution of chemical fertilizer.In the external pollution sources,the main pollution factors for these two reservoirs are using excessive fertilizer in farmland,discharging household garbage and domestic sewage directly,and livestock and poultry wastes running into the reservoirs by overland flow,thus we must conduct an integrated control in these aspects.3.Analyzing the internal pollution source of these two reservoirs,the main substrate sludge is N and P pollution,and the amount of sludge in the total reservoirs capacity is big,so that this is an important accumulation for nutrient substance in reservoirs.Dredging the sludge in reservoirs can improve water holding capacity and water quality,thus can solve the problem of sludge secondary polluted thoroughly.4.The best way to improve water quality of these two reservoirs is adopting integrated control technique by combining engineering management and ecological remediation.And we should overall considerate the reservoir’s local environment and select the best treatment technology by combining community economy factors.Also we need to build healthy ecosystem for reservoirs and enhance self-purification ability of water body,thus we can achieve a sustainable development for the quality of water environment.