Abstract:

Improving water transparency is an important technical pathway for enhancing the visual quality of water bodies. This study analyzed the spatial and temporal distribution, influencing factors, and improvement goals of transparency (SD) in typical water bodies (lakes, rivers inside the polder area, rivers outside the polder area) within the pioneer region of the Yangtze River Delta, based on field monitoring data collected from April to December 2023. The average SD during the monitoring period was approximately 61.17 cm, 68.75 cm, and 45.08 cm for lakes, rivers inside the polder area, and rivers outside the polder area, respectively. Spatially, water bodies in the southeastern area of Xitang town and Lili town displayed higher SD values (>70 cm), while the Yuandang area, the northeast area of Jinze Town, and the Taipu River exhibited lower SD values (<50 cm). Rainfall has a significant impact on SD, particularly in rivers inside the polder area. Correlation analysis indicated that SD was primarily influenced by Suspended Solids (SS), with a negative correlation coefficient ranging from -0.65 to -0.79; The negative correlation between total phosphorus (TP) and SD is particularly significant in lakes, with a correlation coefficient of -0.71; Chlorophyll-a showed a significant correlation with SD, except for rivers inside the polder area. Additionally, fitting curve models were established to further illustrate the relationship between SD and turbidity (Turb), SS, and TP. Among these, the model between SD and turbidity showed the best overall goodness of fit, with an R² value ranging from 0.66 to 0.74. To ensure the survival of the main submerged plants in the nearshore area, it is recommended to set the initial SD target for the pioneer region above the range of 59.14 cm to 83.06 cm.

Key words: pioneer region of the Yangtze River Delta, water transparency, influencing factors, spatial and temporal distribution, correlation analysis