The Analysis Of Ice Organisms, Thickness And Lake Area Evolution Characteristics Of Wuliangsuhai Lake

In recent years, the evolution of lake and wetland has become a global concern among all environmental issues under the dual effects of global warming and human activity. Wuliangsuhai Lake, one of China’s top10fresh water lakes, locates in the Inner Mongolia arid cold area of China, which is the largest natural wetland at the same latitude’s on earth. The study on wetland evolution is an important part of the lakes environmental changes in cold and arid regions. The freezing process and concomitantly environmental changes have a special significance in the research of global environmental changes. In generally, the Wuliangsuhai Lake would be annually frozen from mid November to the next early March. During ice period, the pollutant concentration of the water layer below the ice will be increased. The environmental characteristics of both the ice and water layer will also change according to the ice thickness. So, there is an example about COD (chemical required oxygen) to explain the changes of the environmental characteristics.In this paper, by combining the winter measured data, it calculated the maximum ice thickness and the amount of organic pollutants which was stated by COD as the main parameter. The author combined topographic map, satellite remote sensing image, historical documents and field survey, gave full play to the RS, GIS technology’s advantage in recovering the yellow river’s locations and the WuliangSuHai’s water geography in different periods, to demonstrate the TM/ETM summer data in nearly25years from1986to2010and winter data from2007to2010. Reeds grow in an accelerating speed in recent20years, mainly toward the west bank of the lake and the inner side of the lake. Natural reeds annually grow0.84km2, and artificial reeds annually grow2.2km2on average, however, the growth fluctuates in wide open water area. Using interpretation data from remote sensing in winter, there was a huge difference of organic pollution distribution between the upper ice and the water. Using satellite remote sensing image and routine survey analysis method, the author found out the process of lakes into swamps are driving by hydrological conditions and the distribution of aquatic plants. Water area shrinking mainly appears in the west bank of the lake and the northern area of Xiaohaizi area. The lake is elevating at a speed of6-8mm per year. Reeds grow towards the middle the lake from the shore, and accelerate the process of lake swamping.