关键词: 藻密度；藻类增殖；驱动因子；相关性分析；结构方程模型；南水北调中线总干渠

Abstract: The main canal of the Middle Route of the South-to-North Water Diversion Project is a relatively closed artificial ecosystem, and the proliferation of algae has attracted attention. Based on the monitoring data of water quality and planktonic algae at 8 typical sections of the main canal in 2022, correlation analysis and structural equation models were used to explore the spatial and temporal variation characteristics of algal density and its driving factors. The results show that the algal density in the main canal of the Middle Route of the South-to-North Water Diversion Project increases along the canal, with the highest value reaching 16 million cells/L in summer. The algal density is significantly correlated with , flow rate, and permanganate index. The influence degree of each environmental driving factor on the algal density is as follows: physical and chemical factors (0.540) > nutrient salt factors (0.345) > hydrological factors (0.227), and spatial and hydrological factors have an indirect impact on the algal density. This study reveals the variation law of algal density and its main influencing factors, providing a reference for the water supply management of the Middle Route Project.

Key words: algal density; algae proliferation; driving factors; correlation analysis; structural equation model; main canal of the Middle Route of the South-to-North Water Diversion Project