Study On The Environment Treatment And Protection Planning Of Dian Lake

Water pollution of the Dian Lake is a great problem in Kunming City and Yunnan Province. As a worldwide difficult problem, water pollution of lake is ubiquitous in the world. Pollution control work of main lakes in China has been carried out for more than twenty years, and some achievement has been accomplished. However, the situation of lake protection and pollution control is still unfavorable. For the industrialization of developed countries started decades or even a century earlier than China, therefore water pollution problem of lake in developed country appeared early also. For a lot of work in controlling lake pollution has been done in the last 40 years or so, many experiences in this field have been accumulated. After reading a large number of documents about lake protection and pollution control, in-situ investigation into Lake Biwa, Lake Kasumigaura in Japan and Zurich Lake in Switzerland also have been done, and exchange of experiences in lake pollution control with experts from Japan or Switzerland followed. Thereafter, according to the pollution control and protection of Dian Lake many practical projects have been launched, and my personal involvement in those projects has also deepened my understanding and awareness about lake protection and pollution control.In the first place, this paper discussed and analyzed the reasons of Dian Lake pollution. By giving the shares of three types of pollutants from different pollution sources in Dian Lake, the emphasis of Dian lake protection work has been placed on pollution sources control, in other words, to improve the urban infrastructure of Kunming city. Secondly, integrating the eutrophication of Dian Lake in the latest years and water quality of Dian Lake in the past two decades, further confirmation of major pollutant in Dian Lake was made. On this basis, combined with the compiling of the master plan of Kunming City, intensive study on how to precede work on the protection and pollution control of Dian Lake in the stage of city master planning was made.The results show that: (1) as the fundamental basis and means of guiding and controlling urban construction and development, urban development layout controlling and optimization is an effective and essential measure in the stage of city master planning to protect Dian Lake. Spatial regulation, watershed classified protection and industrial layout adjustment all can strengthen the control of pollution sources. (2) For the drainage system falling behind urban development, the rate of sewage collection remains very low. In the central district of the city, combined system still exists, thus the rate of sewage collection is difficult to be raised, therefore domestic wastes take up the highest proportion in the pollution load of Dian Lake. Some pollutants even take up more than 60% of the total pollution load. For those kinds of pollutants are closely related to municipal infrastructures, and can be significantly reduced by proper city planning. This is the key point of planning control in this paper. (3) For the great coverage of agricultural nonpoint pollution source and the difficulty to control by engineering measures, it can't be properly solved over the world. At present, there are a large number of farmland, nursery, orchard and vegetable greenhouses in the east, southeast and south of Dian Lake. In rainy seasons, a lot of nutrients (N, P, K, and so on) enter rivers from those fields through surface runoff, and get into Dian Lake at last, making agricultural pollution the second largest pollution source of Dian Lake. (4) With the acceleration of urbanization of Kunming city, the built-up area grows rapidly. Types and quantities of pollutants in the surface runoff coming from building surface and urban road surface grow rapidly, too. These pollutants can get into Dian Lake through storm water pipe network and rivers. Urban nonpoint pollution source has already become the third largest pollution source of Dian Lake. This kind of pollution passes rain water pipe network before going into Dian Lake. Thus, it is possible to make some purification accordingly to a certain extent. (6) As the last and most important, ecological restoration is necessary to the final purification of Dian Lake, although it may probably be performed in the last step.As a plateau lake, its protection and pollution control is very difficult. However, considering the protection in the stage of city master planning is necessary and feasible to improve its aquatic environment. In the first place, controlling and optimizing urban development layout, distinguishing the order of importance and urgency by ratio of pollution load and the difficulty of engineering measures must be done, and then more practical measures could be taken to protect Dian Lake. Improving urban infrastructure of drainage system in Dian Lake basin is the most important work to do. And the other measures, such as controlling agriculture nonpoint pollution source and urban nonpoint pollution source, accelerating water diversion project, Enhancing supervision and management system, and so on, will also speed up the pace of ecological environment improvement of Dian Lake.