Temporal-Spatial Characteristics and Trade-off-Synergy Relationships of Water-Related Ecosystem Services in the Yangtze River Basin from 2001 to 2021

The Yangtze River Basin serves as an essential ecological shelter in China, yet it has encountered escalating aquatic ecological challenges. Exploring the spatial-temporal changes and the trade-off-synergy relationships of water-related ecosystem services (WESs) is necessary for formulating management and planning policies targeting the sustainable development of watersheds. In this study, the InVEST model is utilized to evaluate the spatial-temporal variations in water yield (WY), water purification (WP), and soil conservation (SC) in the Yangtze River Basin using remote-sensed data from 2001 to 2021. The spatial overlay method and a correlation analysis were adopted to reveal the trade-off-synergy relationship among the three WESs. Additionally, we performed a comparative analysis across the grid and sub-basin scales. The results showed that the multi-year average WY, WP, and SC were 536.10 mm, 1.32 kg/ha, and 250.08 t/ha, representing increasing rates of 4.74 mm/a, -0.001 kg/ha/a, and 1.88 t/ha/a, respectively. Moreover, the trade-off-synergy relationships of WESs exhibited spatial variability; specifically, the WY-WP, WP-SC, and WY-SC pairs demonstrated reduced synergy magnitude over time. The WES interactions were stable across the scales of interest, while synergy strength showed noticeable variability. The findings may contribute to the sustainable development of the Yangtze River Basin and enhance the comprehensive management of WESs.