| Water diversion project is an important project which can resolve the tail water's future and assure the water quality of water transfer from south to north. The tailing water diversion project of Xuzhou city was studied through statistical data and analysis, spot survey. and monitoring,remote sensing interpretation, numerical simulation and calculation and so on. Some key issues such as water diversion project proposal, key control unit's treatment proposal, regional tail water recycling was studied systematically. Main conclusions are followed :(1) Two proposals were proposed which according to four principles of"interception, storage, reuse and diversion". The route one was special channel about 172.61 kilometers long, which composed by the present river about 63.22 kilometers and newly opened river about 109.39 kilometers. The route two was to make full use of presented river, and was composed by the present river about 141.53 kilometers and newly opened river about 31.16 kilometers. Two proposals can meet the needs of transferring the tail water to the Xinyi river ecological treatment system and flow autotically, attain the goal of agro-irrigation reuse.The Route two can store tail water by the present rivers, which is benefical for tail water reuse.The total investment of the route two is 0.73008 billion RMB, the route one is about 0.89998 billion RMB. So the route two was choosed.(2) The list of pollutant items of key control unit in the tail water diversion area were analyzed, water environment problems were clarified. Some key control units was designed:①Bulao river unit, Pizhou section unit and Fangting river unit of the Grand Canal are key control units in the tail water diversion area. Sewage and industrial wastewater were the two main contributors which can make ammonium and COD overstandard.②the key pollution solution was to build a Jingma river wastewater treatment plant (the third stage of the project), Taoyuan river wastewater treatment plant and Jiawang Dawu wastewater treatment plant. The pollution management of Pizhou section and Fangting river unit of the Grand River were to build Pizhou wastewater treatment plant (the third stage of the project) and Sanba river wastewater treatment plant (the third stage of the project).(3)Tail water reuse plan was established.①the quantity of wastewater treatment was centralized treated which can attain the 49.23×104 m3/d.②tail water quality, agricultural irrigation water quality and irrigation regime was analyzed. The results showed tail water quality can meet the agricultural irrigation.③tail water recycling was proposed. The tail water and the Grand River water were used according to the ration three to seven by electricity-generated plant as cool water. (4) Water quality model of tail water diversion project was proposed and the impact of tail water on the main water diversion channel was forecasted. Results showed tail water diversion can worsen the water quality, water quality of all the monitoring sections were worse than the presented water quality during non-flood season and raining time. The water quality of main water distribution are below the Grade-fifth.(5) The impact of tail water diversion on the groundwater environment which based on the Visual Modeflow software was studied. Results showed①during the forecasted time, groundwater level will rise from 0.77 to 4.04 meter in all evaluated unit. The quantity of leakage will be from 24.87×104 to 136.25×104 m3, the impact area of channel leakage on the groundwater is relatively small, the impact length is from 275 meters to 3110 meters.②The first and second and third and seventh evaluated area maybe salinization-alkalization, whose length is from 50 to 190 meters.③the impact area of COD which seep from the channel is small.(6)Tail water's quality can meet the quality of drying farming and wet farming, but cannot meet the need for vegetable. Cd is the main control element of tail water. It will be the pollution problem in the twenty years.(7)Water environment risk emerging plan was proposed.
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