Spatio-temporal Evolution and Driving Factors of Ecological Environment Quality in the Huaihe River Basin Based on RSEI.

Clarifying the spatio-temporal evolution of the ecological environment quality of a watershed and its response to the natural environment and human factors are crucial for policy implementation in the ecological environment of the watershed. Using the Google earth engine（GEE） to establish a remote sensing ecological index （RSEI）, the spatio-temporal changes in the ecological environment quality of the Huaihe River Basin from 2002 to 2022 were evaluated combined with trend analysis, variation coefficient, and Hurst index. The main driving factors of spatial differentiation of RSEI were explored using the geographic detector. The results showed that： ① In the past 21 years, RSEI of the Huaihe River Basin had generally improved, but it showed a gradual upward-downward trend. Overall, the area of poor and less poor grades decreased, the area of medium grades increased, and the area of good and excellent grades increased. The improved area accounted for 55.93%, and the degraded area accounted for 22.01%. ② In terms of spatial distribution, RSEI gradually deteriorated from east to west （except in the northwest and southwest marginal mountainous areas）. The stability was better in the east and worse in the western and central areas. In the future, the ecological quality change in the basin was prone to be anti-sustainable and mainly improved. ③ Factor detection results showed that the spatial differentiation of RSEI in the basin was mainly driven by vegetation factors, followed by altitude. The interaction between two factors enhanced the driving force for RSEI spatial differentiation, in which the interaction between vegetation factor and elevation had the strongest driving force for RSEI spatial differentiation, reaching 86.3%.