Assessing subtle changes in arid land river basin ecological quality: A study utilizing the PIE engine platform and RSEI

• Ineffectiveness of Specific Year RSEI for Assessing Arid Region EQ Changes. • Urban expansion has to some extent improved the EQ. • The source areas of urban expansion have a recovery period for EQ, will not continue to deteriorate. The ecological environment in arid regions is fragile, with its quality highly sensitive to human activities. The ecological quality (EQ) of arid land river basins is crucial for the populations living within and the overall societal development. This study examines the characteristics and driving factors of EQ changes in a typical arid land river basin from the perspective of capturing subtle variations in the EQ. Firstly, utilizing the Pixel Information Expert Engine (PIE) remote sensing big data platform, the yearly Remote Sensing Based Ecological Index (RSEI) were computed from 2001 to 2023. Subsequently, the Sen’s slope analysis and Mann-Kendall (M−K) trend test were employed to analyze the level of EQ changes in the Urumqi River Basin (URB). Finally, the Optimal Parameters-based Geographical Detector (OPGD) model was utilized to quantitatively assess the driving factors of EQ changes and discuss their underlying reasons. Findings indicate: 1. The URB’s complexity resists representation by individual ecological indicators. RSEI, from the first principal component, captures the basin’s EQ; 2. From 2001 to 2023, the URB showed an EQ deficiency, with areas of improvement, deterioration, and stability at 32.34 %, 22.99 %, and 25.46 % respectively—an overall enhancement. Improvement focused in developed areas, deterioration in reservoirs and middle-lower reaches; 3. Over 23 years, factors like NDVI, NDBSI, and LST had strong influence on RSEI, while Slope, Clay, and Sand had weaker impacts. Interactions among factors boosted RSEI’s explanatory power; 4. Urban expansion in the URB, driven by unused land development, pivotal for improving EQ. Despite requisitioning cultivated land, forest, and grass—key for regional balance—sustained deterioration is not anticipated due to their small areas and potential for recovery. This study aids understanding EQ dynamics in arid river basins, offering sustainable development insights.