Coupling relationship between urbanization and water-related ecosystem services in China's Yangtze River economic Belt and its socio-ecological driving forces: A county-level perspective

"Taking the county as an important carrier to promote urbanization" has been identified as China's most significant strategic planning for urban development. Exploring the level of coordination among both water-related ecosystem services (WES) and urbanization and analyzing their social and ecological drivers at the county-level can benefit in tackling various environmental challenges that arise as a result of the urbanization. This research examined the spatial and temporal variation of WES (i.e., water provision, soil conservation, and water purification services) in the Yangtze River Economic Belt (YREB) from 2000 to 2018 through the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, and a quantitative assessment of urbanization level in terms of population, economy, and urban area increase. Then, coupling coordination degree (CCD) model was then used to assess the extent of coordinated growth of WES and urbanization. Finally, the GeoDetector model and the regionally weighted regression model were used to investigate the influence of multiple factors on the CCD The findings indicate that: 1) Each county unit in the YREB had a significantly higher level of urbanization from 2000 to 2018, with hotspots located primarily in the Shanghai, Jiangsu, Zhejiang and in the vicinity of Wuhan and Chengdu. 2) The WES in the YREB varied considerably between years, but exhibited an upward tendency. 3) The CCD of WES and urbanization in the eastern portion of the YREB is higher than that in the western portion. The level of CCD was increasing but overall low. 4) Land use intensity, nighttime light intensity, and NDVI were the primary determinants of the CCD between WES and urbanization, with considerable heterogeneity in the driving forces between locations. To improve the coordination level between WES and urbanization, differentiated urbanization development schemes and ecological protection measures were proposed based on the findings.