Research On The Water Quality Human Carrying Capacity In The Three Gorges Area

The goal of this dissertation is to seek to realize the water quality measures through discussing the water quality human carrying capacity. The water quality human carrying capacity means the member of population that can be sustainablly supported by a specific nation or area in the predictable period under a certain living standard, and in this period, the intelligence and technology can utilize the water resource carrying capacity. In short words, the water quality carrying capacity is the maximum population member can be hold under certain water quality.After the completion of the dam, the river section in the Three Gorges Area will become a reservoir from a natural river. The river side pollution will become more serious because of the slow down of river velocity, though the water quantity and self-cleaning capacity increase. After analyzing the relationship between human carrying capacity and three main types of the impacting factors: resource factors including arable land, water, forest and mineral resources; environmental factors including water quality and atmosphere quality; and eco-social factors, the water quality is considered be the most important and vital limiting factor to the human carrying capacity in the Three Gorges Area. The pollution carrying capacity of urban river sections is the foundation and controlled condition of calculating the water environmental human carrying capacity with the COD and NH3-N as the control objectives and indicators.In this dissertation, knowledge of several subjects such as environment system engineering, water-conservancylogy, environmentology, hydrodynamics ect. and the new concept of water function plan are adopted, and the pollution carrying capacity of urban river sections is predicted under three different impounding water lines based on the literature survey. The steps are as following: first, water function plan. According to the different functions of the water body such as drinking water, industrial and agricultural utilization, navigation, and landscapes, 11 primary function areas and 39 secondary function areas are classified. Almost all the function areas can meet the standards except some needs reducing the pollution discharges. Secondly, calculate the pollution carrying capacity of the function areas (developing areas and reserving areas) under different water impounding lines with one dimensional and two dimensional models and put forward the permitted discharging amount of all the counties along theYangtse River. Thirdly, predict the industrial pollutant loads and COD and NH₃-N discharging amount per capita under the technology and living standards of the year 2010 as to calculate the water environmental human carrying capacity. When the population amount is controlled in the capacity, the river sides' environment won't be seriously impacted and can meet the function standards through self cleanness, otherwise the environment will be deteriorated.Under the conditions of three different water impounding lines, the permitted pollutants discharging amount are as following: 1) 156m,: COD 14.65 X 104t/a NH3-N 1.25 X 104t/a; 2) 175m,: COD 8.41 X 104t/a, NH3-NX 104t/a. In the year 2010, when the Dam adopts the 156m operational water line, the whole nine districts or counties: Wanzhou District, Puling District, Changshou County, Fengdu County, Zhong County, Kai County, Yunyang County, Fengjie County and Wushan County have a water environmental human carrying capacity (urban population only) of 2.18 million, When the Dam adopts the 175 m operational water line, the water environmental human carrying capacity will be seriously surpassed. And almost all the counties or districts will be overpopulated with a total surpassing population member as 1.72 million urban population. In all the nine districts or counties, Kai County has the fewest capacity.In order to protect the water quality of the reservoir, the scales of towns and cities should not be too large, and medium or small towns should be developed so as to avoid the concentration of large popu...