In arid regions,such as Hexi Corridor in Gansu Province,Northwest China,wetland is rare and valuable especially. There are four wetlands in the middle reaches of the Xida River in Yongchang County of the corridor, i. e.,Liukezhuang,Jiaojiazhuang,Beihaizi and Shengrongsi,with an total area of 20.38 km~2 . Formation of the wetlands results from hydrogeological conditions,which are controlled by landform-structure,and intertransformation and interaction of surface water and groundwater (spring water) . Since the 20th century,wetland area has been gradually reducing and shrinking in the middle reaches with climate warming and the overuse of water resources. The main counter measures to protect the limited wetland resources of this area are to reinforce the ecological environment protection in runoff formation and water conservation areas in the upper reaches of the Xida River and to reduce the use of surface water and exploitation groundwater in the middle reaches.