Impact of ecological engineering on water quality improvement under urbanization: A case study in Xiaoqing river in Jinan, China

The Xiaoqing River serves as Jinan's primary wastewater-receiving watercourse, with municipal reclaimed water constituting its main replenishment source. Consequently, Jinan's urbanization process exerts decisive influence on the river's water quality. Through integrated analysis of urban development and ecological engineering initiatives along the river, this study conducts a temporal analysis (2011–2023) of hydrological and water quality variations in the Jinan section of the Xiaoqing River Basin, systematically investigating urban expansion impacts on aquatic ecosystems. Analysis of multi-contaminant annual variation trends reveals an initial deterioration phase followed by significant water quality improvement, with 2017 marking a pivotal transition point. Post-2017 comprehensive river remediation resulted in marked environmental quality enhancement. However, emerging challenges including escalating mitigation costs and regulatory complexities led to marginal water quality decline after 2023 navigation resumption. Findings suggest that intensified pollution control challenges emerge for Xiaoqing River water quality improvement. However, with the Jinan municipal government's increased focuses on pollution remediation and the development and utilization of Xiaoqing River, it is expected that the water resources, water ecology and water environment of Xiaoqing River will continue to be consolidated and improved after the navigation resumption.