Improving ecological protection Redline from the perspective of water quality protection: A case study in the Tianmu lake watershed, China

Ecological Protection Redline (EPR) is pivotal for constructing an ecological security framework in China. However, the current EPR delineation exhibits deficiencies because the assessment methods predominantly rely on vertical ecological processes, neglecting horizontal interconnections between ecosystems. To address this issue, this study proposed a hydrological distribution model based on water quality purification functions and environmental risk assessment, the research references Chinese drinking water quality standards. We identify the key purification areas and find a high pollutant correlation with a Pearson coefficient of 0.961. Also, the overlap rate between KWPAs and current EPRs is 89.1 %. This paper suggests that the area of the Redline boundary supplement area is 553.46 ha, and suggests that the area of the internal optimization and improvement area is 244.27 ha. Moreover, the study provides a reference tool for identifying areas with significant ecological value of other watersheds.