| The total amount control on discharge of water pollutants is an importantmanagement measure to protect the water quality. At present, the water environmentalmanagement in China is being in the course from “target capacity control” to “loadingcapacity control”. Therefore, research on the total amount control for water pollutants is ofgreat value in theory and practical significance. The dissertation regards the XiangyangReach of the Han River as the study area, and the main contents of this thesis include:(1)the water quality of the Xiangyang Reach was evaluated on the basis of the water qualityrequirements of water functional area during2004-2010. The contribution of pollutantsfrom point and non-point sources and drainage areas were confirmed. The relationshipsamong pollution sources, sewage drains and water functional area in the Xiangyang Reachwere established.(2) The chemical oxygen demand (COD) and ammonia nitrogen (NH3-N)were selected as the control factors, and the allowable pollutant loads entering theXiangyang Reach were estimated using two-dimensional steady state water quality modeland trial-and-error method with different data sets.(3) According to the predicted changesof the flow regimes of the Han River considering hydraulic project operation, thezero-dimensional and two-dimensional models were used to work out the waterenvironmental capacity.(4) The monthly characteristics and seasonal variations of totalmaximum daily load were analysed using the load duration curves on the basis of flowdata of the period from1956to1998, and then the dynamic total pollutant loads controlobjectives were put forward.The main conclusions of this dissertation are generalized as follows:(1) The total annual pollutant loads on the Han River, which came from thewatershed including the point and non-point sources pollution, were32975.64t ofchemical oxygen demand, and4465.31t of ammonia nitrogen in the Xiangyang Reach in2008. Point source pollution produced the most pollutants, with the heaviest pollution loadin Zakou-Qianying. Domestic pollution source has been the main pollution source in thisarea, and the Yuliangzhou wastewater treatment plant outfall, South canal, Jinhuan outfalland Yidao sewage outfall contributed more pollutants load compared with other sewage emissions.(2) On the basis of the water quality requirements of water functional area, the waterenvironmental capacity of the Xiangyang Reach was estimated using the trial-and-errormethod. The loading capacities of the Xiangyang Reach were81406.27t of chemicaloxygen demand and7732.14t of ammonia nitrogen in2008. Except for the Zakou-Yujiahusection with Class Ⅲ of SurfaceWater QualityStandard, the rest of the Xiangyang Reachwas required to reduce the pollutant loads.(3) The water environmental capacity of short term (to2015) and long term (to2020)in the Xiangyang Reach was predicted, and the results indicated that the loading capacityof chemical oxygen demand and ammonia nitrogen will decline in2015compared withthe current status; the loading capacity of ammonia nitrogen in the Zakou-Qianyingsection will reduce by2875.72t; the loading capacity of chemical oxygen demand andammonia nitrogen in the Qianying-Yujiahu section will reduce by1066.74t and100.06t;the loading capacity of ammonia nitrogen in the Yujiahu-Guo’an section will reduce by19.14t.(4) According to the load duration curve of the Xiangyang Reach, the monthly andseasonal variations of total maximum daily load were obtained. The Xiangyang Reach hasmore loading capacity in the wet season from July to September, with the highest loadingcapacity in the Yujiahu section; the maximum daily loads of chemical oxygen demand andammonia nitrogen in this section are3858.45t and192.9t. Summer is the season with thehighest loading capacity, followed by autumn. And then, the targets of loading allocation,assigned to specific month and season within the year, can be confirmed by deduction ofthe Margin of Safety. |
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