【作者】 李雯婷；

【导师】 顾杰；

【作者基本信息】 上海海洋大学 ， 环境科学， 2011， 硕士

【摘要】 长江是我国的第一大河,径流与潮流相互作用异常明显。河口地区具有独特的地理环境,自徐六泾以下,崇明岛将其分为南支和北支,而南支又被长兴岛和横沙岛分为南港和北港,九段沙将南港分为南槽和北槽,最终形成“三级分汊、四口入海”的格局。流域经济的快速发展、人口数量的急剧增加和工农业生产废水的排放造成水环境质量日益恶化,上海的使用水主要取自黄浦江,但无论从水质还是水量上来讲,都不能满足现有的需要,人们目前将长江作为上海的第二水源,如何充分利用长江的淡水资源已成为当务之急。宝钢水库、陈行水库以及青草沙大型水库是上海取用长江水的主要水源地。作为上海市规划的战略水源地,青草沙水源地位于长江口南北港分流口的下方,在上海市水资源安全保障以及城市可持续发展中发挥着重要的作用。研究长江口南支南岸排污口排放的污染物扩散状况,对于保证长江口水质安全,为今后进一步开发利用长江口淡水资源提供了一定的科学依据,在理论和实践上都具有极其重要的意义。本文运用Delft3D-FLOW建立长江口二维水流和水质数学模型,并利用现场实测流速资料对模型进行率定和验证。结合青草沙水源地工程的建设,模拟计算长江口南支南岸主要排污口排放的污染物在丰水期和枯水期扩散状况。结果显示:污染物在南支南岸近岸带形成高浓度污染区,排污口附近污染物浓度较高,并随涨落潮上下移动,白龙港排放口排放的污染物上溯可到达竹园排放口附近;但在陈行、宝钢和青草沙水库附近污染物浓度较低,不会对上海市水源地水质产生不良影响。通过设立的监测点COD浓度变化值显示,丰水期观测点浓度受外海潮流上溯影响,枯水期受上游径流来水影响,除竹园和新河排放口之间的观测点受到排放口污水的影响浓度较高,其余监测点污染物浓度保持较低水平,青草沙水库水域COD浓度为10mg/l,属于Ⅱ类水质,排污口污染物的排放对其水质影响较小。模拟期内,青草沙水质可保证作为上海市水源地饮用水的正常使用。更多还原

【Abstract】 Changjiang river, one of the longest rivers in China, has the largest runoff,and its estuary has a special geographical environment with the interaction of the runoff and the tidal current. The Yangtze River was bifurcated by Chongming Island to south and north branch from Xuliujing, most of the flow go down through the south branch. The south branch was divided into south and north channel by Changxing Island and Hengsha Island. The south channel was bifurcated by Jiuduansha Shoal to south and north passage, therefore three bifurcation areas and four estuarine outlets were formed.With the rapid growth of economy、demand for basin development and the amount of industrial and agricultural wastewater emission increased sharply, the water environment pollution becomes worse and worse.The main water source of Shanghai is from the Huangpu River.Neither the quanlity nor the amount was suitable for drinking, so the Yangtze River was taken as the second water source and how to make full use of that was seriously considered.The main water source to Shanghai from the Yangtze River is Baogang、Chenxing and Qingcaosha reservoir.Qingcaosha reservoir is located below the south and north channel bifurcation.As the planned strategy water source of Shanghai, the Qingcaosha reservoir which supported the water resources security and is sustainable for the development of Shanghai which has an important significance.So it has profound influence on the theory and practice, and provided evidence for further utilization of the Yangtze River fresh water resource and safety.A 2D current and water quality model was set up with Delft3D-FLOW in this research, which was well calibrated and verified with the observed tidal levels and velocities. Considered with the project of the Qingcaosha Water Source, pollution concentration distribution caused by sewage outfalls in the south bank of the Yangtze River during a dry season and flood season are simulated and the computed results show: a high pollution zone appears near the south shore, and moves upward with flood flow and downward with ebb flow, however, it is bounded a limit region around the outfalls.According to the COD concentration of the monitor points in flood and dry season,it can be seen that: the concentration was affected by the tidal current in flood season,and it was affected by the upper runoff in dry season.Since the sewage discharged from the Zhuyuan and Xinhe outfalls,the COD concentration of monitor points,which set between the two outfalls,maintain a high level.And the COD concentration is low in rest of the monitor points.The COD concentration of Qingcaosha is 10mg/l which can be classified as the second class water,and the outfalls has little effect to the water quality. During the tidal period, the water quality of the Qingcaosha water source can ensure the normal water supply as the Shanghai water source.更多还原