| The title of this article is Present Environmental Situation and Sustainable Development of Xingyun Lake in Yuxi City, which was based on 1:50,000 integrated geological survey for Xingyun Lake area made by Yunnan Bureau of Geology and Mineral Resources where the author is working.Xingyun Lake Valley is a relatively flourishing economic region in middle of Yunnan with a population of about 200,000. The Lake is an important water resource for local people, industry and agriculture, which supported the lifeblood of economic development of Jiangchuan County and also regulates the plateau climate of middle of Yunnan, provides water resource and beautifies environment. With the rapid development and increasing population, the continuously increasing industrial, agricultural and domestic sewage drained into the Lake has seriously polluted its water quality as well as the destruction of ecological balance caused by over reclaim around the Lake. All of these has aggravated the Lake's eutrophia, decreased its self-clarification and made the water quality severely worse. Long-term sediment of silt and hydrobios remains has led to severe autogenous pollution and accelerated its senium. Severely polluted water is seriously endangering the health of local people and culture fishery, which restricted economic development of Jiangchuan County. In addition, because Xingyun Lake is the upstream lake of Fuxian Lake—called "Highland Pearl", the water from Xingyun Lake has become the largest pollution source of Fuxian Lake. It is exigent and necessary to study and work out the pollution mechanism to solve the Lake's pollution.In order to protect the environment and find out the reason of the Lake's degeneration, study on eutrophic mechanism, sediment dynamic process and infectant migration and sediment must be done. Scientific basis can be acquired for lake environmental protection and management through the study of the Lake's dynamic process of environmental evolution, inner relationship and dynamic mechanism.Focused on the present environmental situation of Xingyun Lake, this article analyzed the Lake's geochemical background, sedimentation, environmental transformation and regulation of lake filling and sediment, worked out the relationship between human activities and lake evolution which can direct environmental protection and lake recovery.From 1980s to middle of 1990s, the trophic status of lake water had changed from middle to mid-rich eutrophic, belonged to Grade V, undrinkable and only suitable for industry. If necessary measure cannot be taken, lake water cannot be used for industry and living. At present, the pollution of phreatic water is also very serious.Relevant studies on limnology and sedimentology show that the main reason for the destruction of lake ecology is irrational development on lake.Based on field work, information compilation and office work, this article worked out the reason for the Lake's senium and put forward measures on lake environmental protection and recovery: because eutrophia is the largest problem we are facing at present caused byaccumulation of nutrient salts, from now on, drain of polluted matters of every kind should be controlled and waste water from factory, city and village should be drained after clarification; pesticide and fertilizer should be reduced in agriculture as well as to improve irrigation system to reduce drain of rural waste water; recover lake wet land system and cultivate good lake ecology to increase the Lake's ability of clarification. Although surface erosion in Xingyun Lake is very serious which caused its sediment, surface erosion and soil had been controlled to some extent by tree planting. In order to reduce silt flowing into the Lake, measures should also be taken to plant more trees and grass, hillside hills that are not suitable for farming should be converted for forestry and green to decrease erosion in confluence area. |
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