鄂尔多斯沙漠高原湖淖群的形成演化及生态功能探讨

The Formation and Evolution and Ecological Functions of Lakes in Erdos Desert Plateau

湖淖群是鄂尔多斯沙漠高原的重要组成部分,有维持湖滨的植物群落生长、缓和湖泊流域的气候变化、维持生物多样性等作用,具有重要的生态功能。本文从湖淖的形成和补给来源出发,分析了湖淖的特点。从新构造运动、气候变化和人类活动等方面研究了区内湖淖群的演化。研究表明,近年来受气候干旱和人类活动的影响,区内地下水位下降,湖淖补给量减小,是湖淖水域萎缩、生态功能减退的主要原因。这为进一步研究鄂尔多斯高原湖淖群的作用及保护生态环境提供了科学依据。

Lakes as the important ingredient of the Erdos desert plateau have significant ecological functions such as maintaining the life of vegetation on the lakeshore, moderating the climate change around the lakes and keeping the biological diversity in the regions. Since the Erdos desert plateau lays in arid-semiarid regions with scarce precipitation, strong evaporation and vulnerable ecological environment, investigation into the formation and evolution of lakes has been of great significance. According to source of water from, the lakes can be classified into three models. Model 1： the lakes supplied by both precipitation and phreatic, its area of water coverage fluctuating with season. Model 2 ： the lakes supplied by precipitation, phreatic water and confined water, with a large and stable area of water coverage. Model 3： the lakes supplied only by precipitation, featuring with a rapid increase of water coverage in rainy season and disappearance in drought season. Generally, groundwater is the major resource for the lakes＇ water supply in model 1 and 2. For example, groundwater accounts for 80 percent of the total water supply in Hongjian Lake, which is the largest lake in this region. This paper further studies the evolution of lakes driven by new tectonic movement, climate change and human activities. The results show that it is the arid climate and uncontrolled human actives that caused groundwater table decline in the area, which not only reduce the lakes＇ areas, but also degenerate the eco-functions of lakes. According to the characters of lakes, some effective measurements are put forward to maintain areas of lakes so as to protect the eco- environment from being degenerated in Erdos desert plateau. A large amount of groundwater can be extracted around lakes＇ area of model 3 under the condition of meeting water demand for vegetation growth. On the contrary, groundwater should not be exploited around the lakes which belonging to model 1 and model 2. The research offers scientific evidences to further study on functions of lakes in Erdos desert plateau and to protect the ecological environment.