A Study on Eutrophication Status and Driving Factors in Yinjiang Reservoir’s Tributary Bays

Eutrophication, as a global water environment issue, is particularly prominent in the context of cascade hydropower development. This article analyzes water quality variations and nutrient-eutrophication relationships in the bays within the reservoir of Yinjiang Hydropower Station, the final cascade in the Jinsha River's midstream, which provides practical guidance for prioritizing water quality interventions. By applying sobol, PCA and spearman correlation analysis methods, this study identify CODMn, DO and TP as predominant factors influencing trophic state in the Yinjiang reservoir and its tributary bay areas. Analysis revealed strong autocorrelation between CODMn and TP with a rho correlation coefficient of 0.89, indicating concurrent organic matter and nutrient enrichment. The Renhe River tributary requires prioritized attention due to significantly elevated TP concentrations, particularly during dry periods.