| The water body in urban areas, such as lakes, artificial lakes and ring-city rivers, becomes a key part of cities' scenery, playing a role of beautifying surroundings and attracting tourists. Most of the water bodies are combined with the local human and natural landscapes, and with a deep cultural deposit as a result. They are a important element comprising of urban landscape, and thus get the reputation as a city's pearl. However, with the speed of China's economic development surpassing that of environmental protection industry and people's concept, the landscape water bodies bear increasingly heavy burden of urban development and population. With its own characteristics of low ability in flowing and self-cleaning, the input pollutants surpass the wahter body's max loading ability. At present, most of the landscape water quality in China is getting worse, with the major problem as eutrophication.Water eutrophication is that excessive nitrogen,phosphor and other nutrition materials enter into water. As a result of that, alga and. other hydrophytes in the water propagate excessively, resulting in the changes of the transparence of water body and the dissolved oxygen (DO) in water and the depravation of water quality. Finaly the functions and ecological environments of landscape water would be destroyed.Most of water eutrophication is limited by phosphor element, because water will be eutrophicated under the condition of the nitrogen-phosphor scale (N/P) between 10 and 15, which is propitious to the propagation of alga. The content of nitrogen in water is not easily controlled as alga amd other content of nitrogen in water or air and live in the environments with nitrogen element. According to above presentation, phosphor plays an important role in the formation of water eutrophication. That is to say, if we can control the phosphor content in water, i.e. the scale of phosphor and phosphor element is the limited factor in water eutrophication. In order to control the eutrophication effectively, protect the landscape water quality, andutilize water resources scientifically, it is essential to investigate the phosphor content, distribution, and the law of transformation.The two-dimension numerical simulation of water flow and water quality is required in most practical projects, in which two types are divided according to the different water area. In the broad water area such as the coast, estuary, lake and large reservoir, the horizontal scale is far larger than the vertical scale, the variation of hydraulic parameters (for instance, velocity) is smaller in the vertical direction than in the horizontal direction, and the flow field can be expressed as the average flowing value along the water depth, so the two-dimension plane numerical simulation technique of water flow and water quality may be used in these areas. But, in some other water areas such as the narrow-deep tide channel, narrow-deep valley reservoir and narrow-deep estuary area, the vertical varies of parameters such as the velocity, temperature and concentration is far greater than that in the horizontal direction. So the two-dimension vertical numerical simulation technique should be adopted in these areas.Taken Siamese twins landscape Lu-lake for example, this paper proposes a two-dimension numerical model for total phosphor transformation and movements under the condition of encironments around the Lu lake, hydrography and geologic conditions and measure materials. Matlab is used to simulate and calculate. The model has been used to describe the change of disciplinarian of the total phosphor concentration, and many results have been obtained. And the change charts for total phosphor concertration have been produced by matlab. So according to the results under the condition of total phosphor in Lu-lake, the ways of controlling the change of total phosphor can be used by regerring some schemes taken to control the pollution of landscape water in our country and other countries.
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