Spatio-Temporal evolution and motivation analysis of ecological vulnerability in Arid Inland River Basin based on SPCA and remote sensing index: A case study on the Shiyang River Basin

With Shiyang River Basin as the study area, this paper used a remote sensing model to calculate indicators such as greenness, dryness, wetness and heat to construct ecological vulnerability assessment indicators based on the ecological characteristics of Arid Inland River Basin and the characteristics of rapid, objective, and large-area observational remote sensing, which was analyzed the spatio-temporal evolution and motivation of ecological vulnerability by Spatial Principal Component Analysis(SPCA) in 2000 and 2016 in Shiyang River Basin. The research showed that(1) From the spatial distribution of each remote sensing index, the mean of wetness and greenness showed an increasing trend in 17 years, which proved that the water conservation capacity was better and the vegetation coverage was larger in the basin. The mean of dryness had decreased, indicating that the degree of surface exposure of the basin had reduced. The mean of surface temperature closely related to vegetation and water resources was increasing year by year, which indicated that the differences of water and heat balance were further increasing in the basin, which had a significant effect on ecological vulnerability in the future.(2) From the spatio-temporal evolution of ecological vulnerability in the whole basin, the basin was mainly dominated by strong vulnerability and moderate vulnerability, and the ecological vulnerability had been slowly decreasing in 17 years.(3) From the ecological vulnerability distribution at different elevations, the highest in medium mountain area(1000-2000 m), the medium in high-medium mountain area(2000-3000 m), and the lowest in high mountain area(>3000 m). During 17 years of change, the ecological vulnerability of medium mountain area had decreased, while the high-medium mountain area and high mountain area were on the rise.(4) From the ecological vulnerability of different administrative divisions, Jinchuan, Liangzhou, Yongchang, Minqin and Gulang as a whole were at the level of moderate vulnerability and strong vulnerability, while Tianzhu and Sunan were at the level of slight vulnerability and light vulnerability.(5) From the motivation of ecological vulnerability, the four indicators had significant effects on the ecological vulnerability of Shiyang River Basin. The main influencing factors of ecological vulnerability were heat > wetness > greenness > dryness in 2000, and the main influencing factors of ecological vulnerability were heat > dryness > g