Methods and applications for ecological vulnerability evaluation in a hyper-arid oasis: a case study of the Turpan Oasis, China

The Turpan Oasis is a typical fragile environment that lies in an arid region of eastern Xinjiang and is affected by natural conditions and human activities. The severity of the land degradation and desertification in this area is increasing; therefore, ecological vulnerability evaluations are important for environmental management of the region. In this study, theories and methods of evaluating ecological vulnerability and the typical characteristics of ecological vulnerability were summarized. By combining the environmental characteristics of the research area and the driving factors of ecological vulnerability, a multilayer vulnerability evaluation index system was built, and a pressure-state-response model was established to evaluate the ecological vulnerability. GIS and remote sensing technologies were applied to extract each index and create a spatial distribution map of vulnerability. The results showed that the vulnerability index values ranged from 3.08 to 6.59, with an average value of 5.19. Regions with moderate vulnerability accounted for 81.85 % of the total area, whereas regions with light and serious vulnerability accounted for 4.19 and 13.95 % of the total area, respectively. Thus, more than 80 % of the area had moderate vulnerability, and nearly 14 % of the area had serious vulnerability. The degree of vulnerability increased from east to west, and the ecological vulnerability in the inner oasis was significantly lower than that in the outer oasis. The key factors for ecological restoration and reconstruction are to control desertification and to ensure ecological water use to the greatest extent.