Oasis evolution and water resource utilization of a typical area in the inland river basin of an arid area: a case study of the Manas River valley

The Manas River valley is a typical inland river basin of an arid area in central Asia, and illustrates oasis evolution and economic development in this region. Based on the historical documents, monitoring data from field surveys, and remote sensing image data, this paper illustrates the oases evolution over the last 2,000 years and analyzes the rapid expansion of the Manas River oasis in the last 60 years. We also examine the relationship between oasis evolution and water resource utilization. We discuss the characteristics and effects of oasis expansion and the proposed adjustment measures for sustainable development of the Manas River valley. The principal objectives of this paper were to analyze the relationship between oasis expansion and water resource utilization over the last 60 years, and to solve the conflict between the continuous expansion of oases and a shortage of water resources to keep development of the Manas River valley sustainable. The results indicate that (1) oasis evolution in the Manas River valley over 2,000 years can be divided into three periods: a period dominated by animal husbandry, a period of semi-farming and semi-grazing, and a farming-dominated period. During the first two periods, the oasis area was limited, water conservancy facilities were poor and water utilization levels were low. In the third period, oasis expansion over the last 60 years shows a large-scale development. (2) The farming-dominated period can be subdivided into four phases according to the scale of water projects and the level of irrigation. Different oasis scales of the four phases show that artificial oasis evolution has a close connection with water resource utilization. (3) The evolution of oases in the Manas River valley raises some environmental problems although it plays an active role in promoting sustainability. Therefore, adjustment measures for the future development of oases could be proposed from the perspective of sustainable development, such as oasis scale control, forbidding reclamation, moderating exploitation of groundwater, and transforming industrial structures.