Study On Ecological Water Requirements For Restoring The Oasis In Ejina Region

The Ejina oasis is the important ecological barrier in north-China and northwest in China. In history, the Ejina oasia can exist depending on the water resources in Heihe river. But in the recent years, along with the development of social economic and the increasing of human activities, some ecological matters happened due to the decreasing of water resource from Heihe river such as: groundwater table descending, vegetation coverage declining, function of the oasis degenerating and so on. Based on the analysis of driving factors of water and oasis, ecological groundwater table of main vegetation in Ejina oasis was defined through theory on ecological adaptability and model analysis with local environment. Vegetation coverage selected as the main scale index of the oasis ecological function, and the distribution rates of different vegetations and coverages was put forward for different groundwater tables. Considering the research developments of ecological water requirements at home and abroad on, the consistency between ecology standard and ecological water requirements was stressed, and the specific meaning of the ecological water requirements was cleared. Considering the ecosystem water requirement mechanism and the influences of vegetation coverage on ecological water requirements, the method to calculate the natural oasis ecological water requirements in northwest arid region was proposed; according to the assigned water index and ecological restoration level from "Planning of Heihe River Basin in the near Future", the competition relation between oasis area and the ecological function was thought over in the synthesis, regarded the ecological water requirements as main index, the restoration scheme of Ejina oasis in the near future was carried out in this paper.The major research achievements of this paper can be concluded as follows:(1) The water resources decrease is the key reason of Ejina oasis degenerative. The water resource amount that flowed into the Ejina region from the lower reaches of Heihe river during 1957 - 1979 reduced 2 million m~3 annually, and during 1980 - 2000 reduced 13 million m~3 annually. This led to the decrease of groundwater table 0.044m annually in the 90's of 20 centuries in Ejina region, and to the changes of natural...