Northwest China includes Xinjiang Ugyur Autonomous Region, Qinghai Province, Gansu Province, Ningxia Hui Autonomous Region and Shaanxi Province, covering 308×10⁴ km². It is located in the warm-temperate zone and the climate is arid or semi-arid. Precipitation is very scarce but evaporation is extremely high. The climate is dry, the water resources are deficient, the eco-environment is fragile, and the distribution of water resources is uneven. In this region, precipitation is the only input, and evaporation is the only output in the inland rivers, and precipitation, surface water and groundwater change with each other for many times, which benefits the storage and utilization of water resources. The average precipitation in this region is 232 mm, the total precipitation amount is 7003×10⁸ m³/a, the surface water resources are 1891×10⁸ m³/a, the total natural groundwater resources are 1150×10⁸ m³/a, the total available water resources are 438×10⁸ m³/a, and the total water resources are 1996×10⁸ m³/a and per capita water resources are 2278 m³/a. The water resources of the whole area are 5.94×10⁴ m³/(a.km²), being only one-fifth of the mean value in China. Now, the available water resources are 876×10⁸ m³/a, among which groundwater is proximate 130×10⁸ m³/a.