Critical factors affecting rheological properties of surface fluid sediment in one large shallow lake

Large shallow lakes have been plagued by issues such as eutrophication and low water transparency, most of which are related to sediment suspension. Fluid sediment on the surface is gradually receiving attention due to its low density. Here, a typical large shallow lake, the Taihu Lake, was selected to conduct on temporal and spatial variation in surface fluid sediment. Through collecting sediment column samples in different lake areas during four seasons, the surface fluid sediment properties were analyzed. The results indicated that the northwest lake area was covered with fluid sediment in four seasons. And the fluid sediment coverage areas in January and October were larger than that in April and July. In order to understand the changes in sediment structure, we calculated the proportions of sediment components and measured the sediment particle size distribution and organic matters contents. According to the pairwise comparisons and structural equation model (SEM) analysis, it can be concluded that sediment particle size, density, and organic matters jointly affected sediment stability. And sediment D₅₀ was the main driving force affecting sediment yield shear stress (τ_y). Then sediment critical shear stress (τ_c) was calculated combined with τ_y to clarify the sediment suspension capacity. Overall, the results can deepen our understanding of the fluid sediment properties in lakes, and help with the restoration and management of lake sediment.