Hydrological changes and land degradation in the southern and eastern Tarim Basin, Xinjiang, China

Using the combined methods of digital image processing of remote sensing data, a Geographical Information System (GIS) and analysis of historical books and maps, this paper aims to contribute to a better understanding of the processes and mechanisms of land-use and land-cover changes and hydrological variations during the last 2000 years in a hyper-arid environment. The southern and eastern Taklamakan Desert, one of the driest and ecologically most sensitive regions in China and characterized by a long history of human settlements, was chosen as the study area. A hydrological connection between the Keriya and Niya rivers in former times was recognized for the first time using satellite imagery. After transferring the notes and maps of historical times into a simplified modem map, it shows that the Lop Nuer decreased in size from a large lake in the Han Dynasty (206 BC to AD 220) to a much smaller one in the Qing Dynasty (AD 1644-1911). Areas settled in former times differ morphologically from the dune landscape in satellite imagery because of flat relief along dried river courses. A review of archaeological literature reinforces the fact that in the lower reaches of the Keriya and Niya rivers, in the interior of the Taklamakan Desert, irrigated agriculture was widely practised from ca. 200 BC to ca. AD 500. A possible climatic change toward drier conditions at ca. AD 500 is suggested as the cause of the abandonment of the cities in the desert and for the initial drying of the formerly large Lop Nuer Lake. Copyright (c) 2006 John Wiley & Sons, Ltd.