Study On Dispatching Scheme Of Water Diversion And Pollution Control From The Yangtze River In The Lixiahe Hinterland Based On Mike 11

The hinterland of Lixiahe is located in the lower reaches of Huaihe River Basin.The river network is crisscrossed with abundant rainfall.It is a typical polder area of water network.With the development of social economy,aquatic ecological environment is facing three major problems:serious non-point source pollution caused by chemical fertilizers,pesticides and fishery culture,increasingly serious production and living pollution and deterioration of wetland function,which have become the constraints of sustainable and healthy development of regional social economy.The water use in the hinterland of Lixiahe is mainly diverted from the Yangtze River by the Jiangdu and Gaogang hydro-junctions,and the high-quality water source of the Yangtze River enters the area through the Xintongyang Canal and the Taizhouyinjiang River to meet the water demand of domestic,industrial and agricultural production.Water diversion project's reducing or stopping the introduction of Yangtze River water to ensure flood control safety in the flood season and Water diversion project's introducing less water into the area due to the low tidal level of the Yangtze river are the main cases of water quality deterioration in part of flood season and non-flood season.In this paper,based on the river cross section data and hydrological and water quality data of the hinterland of Lixiahe,the hydrodynamic model and water quality model are established by using MIKE 11 software.The optimal dispatching schemes of water control projects along the Yangtze River in flood and non-flood seasons are studied to increase the fluidity of waterbody and solve the periodic deterioration of water quality.The water quality data measured in January and September,2017 is selected as the background values of pollutants in typical non-flood and flood rivers respectively.According to the requirements of water quality target of type III in the region,the optimal dispatching schemes of water control projects along the Yangtze River are determined by comparing flood control safety,diversion cost and water quality improvement effect of different schemes.The main results of the research are as follows:(1)In the flood season,when the water quality in the region is mainly classified as IV and V,four schemes with the upstream diversion flow and downstream drainage flow of 200 m3/s,300 m3/s,400 m3/s and 500 m3/s are simulated.The concentrations of ammonia nitrogen and permanganate index of typical sections of rivers in the region are reduced to the water quality standard of Class III within 20,15,11 and 9 days respectively.The driving water volumes are 691.2 million m3,777.6 million m3,760.32 million m3 and 777.6 million m3 respectively.The water levels of Xinghua Station are 1.248m,1.28m,1.305m and 1.33m respectively,and the diversion costs are 4.49 million yuan,5.05 million yuan,4.94 million yuan and 505 million yuan respectively.The four schemes have little difference in driving water quantity and diversion cost.When the diversion flow is 500 m3/s,Xinghua Station water level exceeds the flood control level in the hinterland of Lixiahe.Because the 400 m3/s diversion flow can improve the water quality in a short time and the water level of Xinghua Station is within the safe range of flood control,it is the optimal diversion scheme in flood season.(2)In the non-flood season,when the water quality in the region is mainly of Class III and some areas have Class IV and V water bodies,three schemes with the upstream diversion flow and downstream displacement of 150 m3/s,200 m3/s and 250 m3/s(100 m3/s is the artesian water diversion flow,and the rest are the pumping station)are simulated.The concentrations of ammonia nitrogen and permanganate index in typical sections of each river is reduced to the water quality standard of Class III within 15,13 and 10 days respectively.The driving water volumes are 388.8 million m3,449.28 million m3 and 432 million m3 respectively.The costs of water diversion are 3.08 million yuan,3.93 million yuan and 3.78 million yuan respectively.Considering the three factors,250 m3/s diversion flow is the optimal diversion scheme for non-flood season.