Comparing multiple assessment methods based on water quality, habitat and organism indicators: unveiling the ecological health of Ningbo's urban rivers.

The growing urgency of assessing aquatic ecosystem health has drawn increasing attention due to mounting environmental pressures. While numerous studies have assessed riverine ecological health, most rely on a single assessment method, often neglecting the integration of multiple indicators. This study advances existing research by comparing different assessment approaches to evaluate ecological health of urban rivers. Specifically, we employed three methods, the Water Quality Index (WQI), the Qualitative Habitat Evaluation Index (QHEI), and Shannon-Wiener index (H'), to assess the ecological condition of 15 rivers in Ningbo, Zhejiang Province, China. The results showed that: (i) there was a high degree of congruency between H' and QHEI, but WQI was moderately or weakly correlated with QHEI and H'; (ii) the ecological health status of rivers in southern Ningbo was generally in the upper-middle level, whereas rivers in northern and central regions predominantly fell into the lower-middle level. This study highlights the value of employing multiple complementary assessment methods to capture a more comprehensive picture of aquatic ecosystem health. The findings offer a scientific foundation for water resource management by local governments, fostering the sustainable use of water resources and long-term ecological protection.