3Chen A. Urbanization and disparities in China:Challenges of growth and development[J].{H}China Economic Review,2002,(4):407-411.
4Ma J Z,Wang X S,Edmunds W M. The characteristics of groundwater resources and their changes under the impacts of human activity in the arid Northwest China:A case study of the Shiyang River Basin[J].Arid Environ,2005,(2):277-295.