Dian Lake, also known as Kunming Lake, is the largest freshwater lake in Yunnan Province. Dian Lake is located south of Kunming city, 5 kilometers from the city centre. Because of its magnificent scenery, Dian Lake has always been a popular holiday resort. It is an important asset not only for tourism, but is also for econmic activities such as shipping, fishing, irrigation, water provision, etc. In 1988, Dian Lake was awarded a status as one of the National Scenic Areas by the State Council1. However, tourism has not always been a blessing for Dian Lake. Since 1980, as a result of rapid urbanisation in China, water pollution in Dian Lake has been progressively increasing2.
The reasons for the deterioration of the water quality include the following:
- As Dian Lake has aged, it has evolved to become a semi-enclosed lake, and its rate of flow has slowed down. This has caused a large quantity of pollutants to be deposited at the bottom of the lake.
- Discharges from domestic and industrial sewage are the second reason. Studies show that domestic sewage has been the main source of pollution in recent years. The urbanized area of Kunming accounts for 5% of the drainage area of Dian Lake, but its output of pollutants amount to more than 50% of the pollution in the lake. The main sources of pollution are the fast growing population and the increasing number of factories3.
- The overdevelopment of coastal Dian Lake is the third reason. Tourism and industrial activities, as well as the daily activities of Kunming citizens, have seriously effected the Dian Lake ecosystem. As a result of the exploitation of land resources, Dian Lake has lost its natural defenses; it therefore cannot fight against pollution from domestic wastewater, and other types of pollution.
In order to preserve the environment of Dian Lake, the Kunming city government enstated the “Dian Lake Protection Act” in 1998. The objective was to improve water quality and reduce pollution. This act was modified and re-enstated in 20134. According to the new terms, the government regulates the sewage discharge and also is responsible for setting up a special fund to administer the ecological compensation. The purpose is not only to reduce water pollution in Dian Lake, but also to restore its original natural appearance.
Water pollution is the accumulated damage to water resources over many decades. Generally, it takes at least 10 to 20 years for environmental management to show significant results. In addition, there is no precedent in history of a lake that is being polluted fully recovering. This means that the management of lake water pollution is a difficult and complex project requiring a long period of time to be completed; it indicates that Kunming Dian Lake still has a long way to go.
- Dianchi jianjie 滇池简介, http://special.yunnan.cn/feature3/html/2011-05/23/content_1627042.htm, Retrieved May 6, 2013 [↩]
- Ma Wei et al. (2007) Investigation on countermeasures for water environment management and water pollution prevention in Dianchi Lake, Journal of China institute of water resources and hydropower research. Vol. 5(1), pp. 8-14. [↩]
- Wang Yuchao, Peng Yongan, Li Yimin (2004), The Characteristic of water pollution and engineering-oriented prevention on Dianchi, Areal research and development, Vol 23(1). pp88-91. [↩]
- Guowuyuan guanyu dianchi liuyu shui wuran fangzhi “jiuwu” jihua ji 2010 nian guihua de pifu 国务院关于滇池流域水污染防治“九五”计划及2010年规划的批复, http://www.hflib.gov.cn/law/law/falvfagui2/JJF/FLFG/NL%20ZRZY%20HJBH/1160.htm, Retrieved May 6, 2013 [↩]