白洋淀最低生态水位研究

A study of the lowest ecological water level of Baiyangdian Lake

由于自然条件的变化、工农业的不合理开发、人口的剧增以及水库和涵闸水利设施的盲目建设等,引发了白洋淀一系列生态环境问题,主要表现为干淀、水污染、生态环境退化、泥沙淤积、湖泊萎缩以及航运中断等。恢复和重建已遭破坏的白洋淀湿地生态系统,并使其至少维持在最低生态水位上是至关重要的问题。在分析白洋淀生态系统功能的基础上,利用水量面积法、最低年平均水位法、年保证率设定法和功能法等4种方法对其最低生态水位进行分析和计算,计算结果分别为7.32 m、7.33m、7.2 8m和7.2 7m。通过合理性分析,认为取它们的平均值即7.30 m作为白洋淀最低生态水位是合理的,符合白洋淀实际情况。

Baiyangdian lake is a sluice depression which is naturally-formed by Daqing River. It possesses a number of functions such as flood control, microclimate maintenance water storage and supply, fishery and reed production. In addition, Baiyangdian lake is a perfect place to develop navigation and tourism. It plays an important role in maintaining the ecological balance of this area. However, in the past half century, Baiyangdian lake has been facing a series of eco-environmental problems such as water shortage, water pollution, eco-environmental degradation, siltation, lake shrinkage and navigation interruption, which is the result of the change of natural conditions, irrational development of industry and agriculture, rapid growth of population, poorly planned construction of the reservoir and culvert water conservancy, etc.. It is very important to restore and rebuild the destroyed wetland ecosystem of Baiyangdian lake and maintain the lowest ecological water level at least. And the key problem is how to maintain the lowest water level of Baiyangdian lake. Therefore, a study of the lowest ecological water level in Baiyangdian lake is not only the urgent heed in the eco-environmental construction of the basin but also an important aspect to achieve the sustainable utilization of the water resources. In light of the present environmental problems of Baiyangdian lake, the ecosystem functions are in depth analyzed. Based on the analysis, the lowest ecological water level is studied and calculated using water quantity area method, lowest mean annual water level method, year guarantee setting method and function method. The results are 7.32m, 7.33m, 7.28m and 7.27m, respectively, and the average value 7.30m is considered as the lowest control water level. According to the rationality analysis, the results show that only the water level is higher than 7.30m, can the ecosystem structure be guaranteed, the normal ecosystem function be fully played, the bio diversity and the ecosystem integrality be maintained. However, when the water level is lower than 7.30m, the population structure and quantity of the aquatic species are obviously changed, and the ecological balance is destroyed. Therefore, it is reasonable to make the average value 7.30m as the lowest ecological water level.