The effects of human activities on oasis climate and hydrologic environment in the Aksu River Basin,Xinjiang, China

Under the influence of human activities, the differences in climate changes emerged obviously in the Aksu Oasis. The summer air temperature in Aksu City increased at a rate of 0.20°C·(10 annum)⁻¹, while the air temperature in Aler in summer decreased at a rate of −0.27°C·(10 annum)⁻¹. Human intervention has become the dominant factor in the the changes of water resources in the Aksu Oasis. Compared with the Xidaqiao hydrological station, which is located on the upper reaches of the Aksu River, the runoff ratio at the Aler hydrological station increased in summer and decreased in spring. Though the natural water inflow has increased in the last 50 years, irrigation diversion and water consumption for human activities have increased unceasingly due to the increased reclamation of land and the development of extensive agriculture. The water quality at the Xidaqiao station is in Grade I at different periods, and the water quality at the Aler station of the Tarim River is good because the river did not suffer from human disturbance before the large-scale development of oasis agriculture; but the salinity of river water increased from 0.67 g L⁻¹ in 1960 to 5.27 g L⁻¹ in 2000 at the Aler station after farmland development, reclamation and salt washing in the oasis. The geographic distribution of surface water resources has changed due to human activities and in turn affected groundwater replenishment, bringing about changes to groundwater table and quality.