[Analysis of the Spatiotemporal Distribution Characteristics and Influencing Factors of River Water Quality in Suzhou City].

River ecosystems are dynamic， open， and continuous systems that provide rich material resources and important survival environments for humans. Analyzing the temporal and spatial trends of urban river water quality and the influencing factors is of great significance for taking targeted measures to improve water environmental quality and alleviate water resource shortages. In this study， Suzhou located in the hinterland of the Taihu Lake Basin was taken as the study area to explore the characteristics of urban river water quality change. Based on the water quality monitoring data from 2008 to 2021， the study used the comprehensive water quality index （WQI） and geographical detector to investigate the long-term spatiotemporal trends and influencing factors of river water quality. The results showed that the median annual WQI value of river water in Suzhou increased from 51.16 in 2008 to 71.17 in 2021， indicating a gradual improvement in water quality. The water quality has significantly improved since 2016， which can be mainly attributed to a series of water quality control projects and policies implemented in Suzhou. In terms of seasonal differences， the median WQI values in the wet season， dry season， and normal flow season were 57.89， 61.58， and 63.68， respectively， with water quality in the wet season mainly affected by non-point source pollution. The water quality in all districts of Suzhou had improved significantly from 2008 to 2021， with Zhangjiagang exhibiting the best water quality， where all monitoring points showed good water quality， and Gusu District had the lowest proportion of good water quality due to a high percentage of construction land and high population density. In 2008， temperature and GDP were the main influencing factors of river water quality. By 2021， the impact of temperature and GDP on river water quality had decreased， while the influence of population density and land use on water quality had increased. The interaction of any two influencing factors had a higher explanatory power in Suzhou River water quality than a single factor alone， indicating that the water quality was influenced by a variety of factors from both nature and human activities， with the impact of human factors gradually surpassing natural factors. Additionally， the impact of natural and human factors on water quality was greater in the dry season than in the wet season. This study can provide a scientific reference for accurately identifying water quality influencing factors and proposing precise pollution prevention and control measures for surface water bodies in Suzhou and similar regions.