Study on Ecological Water Use of Mainly Vegetation in Desertificated and Degenerated Grassland of Hunshandake Desert

China is one of the most severe countries influenced by the desertification in the world.Desertification accuvred in the tender ecological condition region.There is 210,000-hectare desertification grassland only in Hunshandake Desert.The economic losses are about 5billian per year.Because of the deterioration of grassland,the development of livestock raising is affected enormously.In this paper,the water balance method and physiological index of main vegetation are adopted,to study the actual water use,define the quantity of water use and reach the aiming in arid and semi-arid area.It is important for river basin plans,ecological construction and reasonable allocate of water resources.