Water quality variation and driving factors quantitatively evaluation of urban lakes during quick socioeconomic development

Rapid urbanisation has caused a significant impact on the ecological environment of urban lakes in the world. To maintain the harmonious development of urban progress and water quality, it is essential to evaluate water quality variation and explore the driving factors quantitatively. A comprehensive evaluation method with cluster analysis and Kriging interpolation was used to explore the spatiotemporal variation in a typical urban lake in China, Chaohu Lake, from 2011 to 2020. The correlation between water quality and socioeconomic factors was evaluated by Pearson correlation analysis. Results indicated that: total phosphorus (TP) and total nitrogen (TN) were the key pollution parameters of Chaohu Lake. The pollution situation was gradually improving, however, and the improvement in chemical oxygen demand (COD) is more evident due to anthropogenic control. The spatial heterogeneity of water quality in Chaohu Lake is remarkable, and the water quality is poor in the west but better in the east. Natural attributes of lakes and external load were the main reasons for the spatial heterogeneity. The western residential areas of Chaohu Lake Basin (CLB) are concentrated, and a large amount of industrial and domestic sewage exacerbates water pollution in the west of tributaries. In contrast, the implementation of water environmental governance policies in recent years has alleviated water pollution. From 2011 to 2020, water quality has improved by 23%-35% in the west and 7%-14% in the east. This study provided a framework for quantitatively assessing water quality variation and its driving forces in urban lakes.

Automated summary

Rapid urbanisation has had a significant impact on the ecological environment of urban lakes worldwide. In order to maintain the harmony between urban progress and water quality, it is crucial to quantitatively evaluate water quality variation and explore driving factors. This study used a comprehensive evaluation method with cluster analysis and Kriging interpolation to investigate the spatiotemporal variation of Chaohu Lake, a typical urban lake in China, from 2011 to 2020. The results showed that total phosphorus and total nitrogen were the key pollution parameters of the lake. The water quality improved gradually, especially in terms of chemical oxygen demand due to anthropogenic control. There was notable spatial heterogeneity in water quality, with better water quality in the east compared to the west. The study also identified the main reasons for this spatial heterogeneity, which were the natural attributes of the lake and external load. The concentration of residential areas and the discharge of industrial and domestic sewage aggravated water pollution in the western tributaries of Chaohu Lake Basin. However, recent water environmental governance policies have helped alleviate water pollution, leading to significant improvement in water quality in both the west and east regions.