Study On Water Environmental Quality Regulation And Control In Putian Based On Water Resources Allocation

Putian is a burgeoning port city in Fujian Province of Chinese economic zone on the west coast of the strait. In the accelerating process of urbanization, the rapidly increasing ecnomical development, the engineering water shortage and water pollution in urban inner rivers have been the major obstacles and constraints to the economical growth of the city. The present quality of water environment in Putian is declining, especially the water in central urban area which has partly lost its using function or even entirely. Because of the point-source pollution from industry and urban life, the pollution quantity of entering river has badly exceeded the water environment capacity of the water functional areas, which has made the situation worried. As one of the pilot cities of water ecological civilization construction, Putian should ensure the water demand for future life and industrial development. Moreover, the relationship between the exploration and protection of water resources should be managed well, and the quality of water environment and the benefits of water ecology should be taken seriously. Based on the water resources allocation and combined with the water dilution schemes which are simulated by water quality model for river networks, the study regulates and controls the improvement of the water environmental quality in Putian by analyzing and calculating the water environment capacity and the controlling quantity of the pollution into the river and set monthly reduction plan reasonably. The study is organized as the followings:(1) The plan of water diversion for the Beiyang river networks in central urban area which is polluted heavily was simulated by the water quality model MIKE11. It meaned clean water would be delivered into the area monthly for the dilution of pollutant concentration to improve the recent water quality to standard V.(2) Considering the economical & social development and the minimum ecological water demand in the future level years, the water-allocation schemes in 2020 and 2030 were established by setting the new water storage and diversion projects. Combined with the target of the water diversion for the Beiyang river networks, the reasonable allocation schemes to improve water environmental quality were proposed by contrasting the monthly satisfaction level to the water diversion from the discharge volume of the main ecological control sections.(3) An improved method was put forward to calculate the water environment capacity of the water functional areas in Putian, which used the minimum discharge every month in recent 10 years as the design discharge to calculate the monthly capacity. The capacity allover the year from the calculation rule which used the discharge in dry season as the design hydrological condition was contrasted to be simply safe. The new method could objectively reflect the changes of the capacity varied with the dynamic volume in flood season and non-flood season of a whole year.(4) The controlling quantity of the pollution into the river and the monthly reduction plan were set based on the improved method. The monthly controlling quantities of the pollution (COD, NH3-N) in the two overproof water functional areas were analysed and calculated through the method. Considering the present and pollution of entering river respectively, the monthly reduction plan for the water functional areas and the yearly reduction plan for the main pollution emitted units were both made. They could supply supports and references for Putian to improve the water environmental quality and make the compositive solution in the future against the badly polluted situation in central urban area.