Abstract:

The Ejin Oasis， situated in the lower reaches of the Heihe River along the China-Mongolia border， experiences ecological restoration/degradation that is directly influenced by land use. However， the impact of ecological water diversion projects on land use remains unclear. Based on remote sensing image data， spatial information technology and statistical methods were used to investigate the patterns and processes of land use/cover changes before （1980-2000） and after （2000-2020） the implementation of ecological water diversion projects， as well as their effects on desertification processes. The results indicated that the structure and composition of land use and cover in the Ejin Oasis were stable， with desert， grassland， woodland， water， cropland， and construction lands accounting for 79.77%， 17.55%， 1.48%， 0.76%， 0.18%， and 0.26% of the total area in 2020， respectively. Moreover， frequent and large-scale transfers occurred between grassland and desert， and the process of land desertification was centered on changes in water sources. Before 2000， grassland， woodland， and water were converted into desert， resulting in oasis desertification， which intensified from 1990 to 2000. After 2000， the process was exactly the opposite， with the greening of the desert oasis. Furthermore， the ecological water diversion projects also facilitated socio-economic development， characterized by a thriving agriculture and tourism industry. This was evident in the rapid increase of cropland and construction lands. The cropland was expanded by 55.36% from 2000 to 2010， remaining stable thereafter. Likewise， the construction land surged by 142.11% from 2000 to 2010 and 186.96% from 2010 to 2020. The findings provide scientific references for regional water resource allocation and ecological environmental protection.

Key words: ecological water diversion project, land use/coverage, lower reaches of the Heihe River Basin, Ejin Oasis