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Study region: National Sustainable Development Agenda Innovation Demonstration Zone in Lincang City, Southwest China Study focus: Revealing the current water quality status in rivers and reservoirs and its drivers is crucial to achieving the United Nations Sustainable Development Goal 6 (SDG 6). We assessed the spatial-temporal dynamics and influence of natural and socioeconomic factors on the water quality index (WQI) and water quality parameters of rivers and reservoirs using redundancy analysis (RDA) and the partial least squares path model (PLSPM). New hydrological insights for the region: The results indicate the following. (1) The annual average values of the WQI in Lincang City from 2018 to 2020 were 92.26, 92.06, and 92.45, respectively. The WQI values in spring, summer, autumn, and winter were 92.48, 90.38, 92.68, and 93.49, respectively. The annual and seasonal water quality levels were good or higher. However, spatial heterogeneity exists for some water quality parameters in Lincang City. (2) The influence of natural and socioeconomic factors on the WQI and water quality parameters is highly complex. The landscape composition, landscape configuration, and pollutant discharges are key factors affecting the water quality of rivers and reservoirs annually and seasonally, and a spatial scale dependence is observed. (3) Chemical and physical factors directly affect the WQI, particularly at small scales (100 m and 500 m buffer zones). Chemical factors have a strong inhibitory effect on the WQI of reservoirs (−0.79, −0.78) and rivers (−0.56, −0.72), whereas physical factors have a weak promoting effect (0.05–0.13). Landscape composition and landscape configuration and indirectly affect the WQI. In contrast, socioeconomic factors and pollution discharge indirectly impact the WQI of rivers and reservoirs through their influence on chemical and physical factors. These findings demonstrate that natural and social factors interact in multiple ways, impacting the water quality of rivers and reservoirs. This interaction depends on the spatial scale. Therefore, it is crucial to consider the appropriate distance from rivers and reservoirs in future land use planning, particularly in the landscape design and planning in Lincang City. Moreover, controlling wastewater discharge from industrial and agricultural activities and domestic water usage is vital for ensuring high water quality. |
