Author(s): Hyoseob Noh; Yong Sung Park; Il Won Seo
Linked Author(s): Yong Sung Park, Il Won Seo
Keywords: Total Sediment Load Suspended-to-Total Load Fraction UMAP Pattern Analysis Turbulence-driven Suspension Bedload-related Transport
Abstract: Measurement of total sediment load in natural rivers is crucial for river management. However, direct measurement of bedload is challenging, leading to the common practice of estimating total sediment load using measured suspended sediment load. One can leverage a suspended-to-total load fraction (F_sus). In this study, we analyzed sediment load data using Uniform Manifold Approximation and Projection (UMAP), a dimensionality reduction technique, to understand the mechanism and improve estimation performance for F_sus. The application of UMAP revealed three distinct patterns in the suspended-to-total sediment load fraction. The first pattern showed a positive correlation between the flow depth Reynolds number and F_sus, indicating turbulence-driven suspension. The second and third patterns, associated with coarser sediments and lower flow energies, suggested more bedload-related transport mechanisms, being less influenced by the Reynolds number. The three patterns compositely show a radial increasing pattern of the UMAP parameters with an increase of F_sus. We also demonstrated that linear regression can be utilized for estimation, as the radial distance in UMAP space showed a strong positive correlation with F_sus. It is expected that the performance of total sediment load estimation models based on suspended sediment load can be enhanced by considering the regime shift and utilizing UMAP space variables.
Year: 2025