A One Dimension Water Body Eutrophication Model Computer Simulation Of Chongqing Section In The Three Gorges Reservior

It is undeniable that the Three Gorges project, an enormous one for the muti-development of water resource , makes great contribution to many aspects such as flood control, power generation, water transportation, etc, but as a result , to some extent, it also has brought about some bad effects on the ecological environment of the Three Gorges area. As pointed out in the report of the key project influence on environment issued in December, 1991 by the Environment Evaluation Department of the Chinese Academy of Science and the Scientific Research Center of the Yangtze River Water Resource Protection bureau, it is likely to raise question of eutrophication in partial back water area .Therefore, the matter of ecological environment, particularly the one of eutrophication, has been heightened both in home and abroad. To approve it, authorized by the Ministry of National Science and Technology, Chongqing Institue of Environmental Science, after conducting a thorough investigation in Daning River(Wushan County), Meixi River ( Fengjie County), as well as Xiaojiang River(Yunyang County) by professional, found out that there indeed exists a question of eutropication with different level in the three above-mentioned back water area. To have a clearer idea of the current and future situation of the eutrophication in the three above-mentioned back area, it is necessary and urgent to carry out a computer simulation about the main factors of typical water eutrophication in the Three Gorges area in a quantitative and systematic methods.In this paper , we adopt a one-dimension water quality model from Sino-Britain cooperation project —A Collection of Technology Subreport of Water Polution, Control and Regulation, as well as an algae growth hydraulics model from the tackle key problem project in the 10^th five-year plan of the Ministry of National Science and Technology—the Eutrophication of Back Water Area in the Tributary Entrance of the Three Gorges Area.Based on this, we also made some conformity about the two models in accordance with the need of research. This paper aslo programs the selected mathematical model with the aid of the new generation of computer programming language—FORTRAN 95, and programs a friendly user interface through VISUAL BASIC.With this in hand, as long as users input the control parameter and the raw data in a given pattern, they can getthe simulation index of the water eutrophication without much efforts and make a reliable decision whether impact factors should be observed closely or not according to the warning message from the simulation results including the level of eutrophication.The main conclusion can be draw as follows:(DBased on the one-dimension water eutrophication model which is able to simulate the lengthways distribution of the impact fators such as water flow, water quality (CODmn, TN, TP, DO) and Chla, the relatively better accuracy property of the simulation is approved after compared with the two results from the spot survey and the simulation. The model can also be used to simulate and predict the situation of water eutrophication in main rivers and tributaries, river net, etc.(2)Due to the section area increasing after water storage in the Three Gorges Reservoir, the result is the relatively decreasing section average water speed under the same water flow condition than that in a natural state. The reduced water velocity leads to the prolonged track time of polluted things which meander in back water area, which makes water eutrophication to take the upper hand.(3)Although the aboundant fog and rain as well as the rare sunshine and sun radialization is unagreeable to the growth of algae on the one hand, the water temperature in spring , sumer, altumn, with the coincidence and concentration of lux, heat, is agreeable to the growth of algae, which provides the necessary condition of lux, heat needed for the occurrence of water eutrophication .(4)The water from the backwater region of Daning River, Meixi River, Xiaojiang River, the contaminated substance from the upper stream of rivers and the chemicals from the drowned soil as well as the polluted water from the banks of river (the domestical and industrial waste water) —all these bring about heavy nutrition load such as nitrogen, phosphorus which could meet the rapid growth demands of algae in a large scale.