199-3 Coupling Remote Sensing with DEM-based 3D Computational Fluid Dynamic Modeling to Analyze Planform changes in different parts of the Culebrinas River

Session: Advances in Fluvial Processes and Sediment Transport, Part II

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Abstract: Predicting river planform changes requires analyzing numerous hydrodynamic and geomorphological parameters. Many of these factors are difficult to measure directly in the field or laboratory. Numerical models play a crucial role in estimating such parameters, but their accuracy must be validated against observational data. This study presents a three-dimensional, three-phase Computational Fluid Dynamics (CFD) simulation of a field-scale segment of the Culebrinas River in Puerto Rico using ANSYS Fluent. The river geometry was reconstructed from a 1 m resolution Digital Elevation Model (DEM), and a three-phase Eulerian framework was employed to model interactions among air, water, and sediment. Model performance was evaluated by comparing simulated water surface elevations (WSE) to ICESat-2 photon data products (ATL03 and ATL06). Predicted sediment deposition zones were also compared with patterns observed in high-resolution Google Earth imagery. In addition, historical river centerlines from 1936 to 2019 were extracted from aerial imagery to quantify planform changes and identify key factors influencing those changes. Results indicate that the 3D CFD model effectively captures complex hydrodynamic behavior, including secondary flow in meandering sections and associated sediment deposition patterns. The root mean square error (RMSE) between simulated and observed WSE values ranged from 0.19 m to 1.31 m across multiple discharge conditions, demonstrating the model’s reliability despite inherent uncertainties. This integrated modeling and remote-sensing approach underscores the value of combining CFD simulations with satellite and aerial observations for improved flood hazard assessment and morphological analysis in tropical river systems. Furthermore, sections of the river with more pronounced secondary flows exhibited the greatest planform changes.

Keywords: Dem based Computational fluid dynamic model, Remote sensing, historical aerial image, ICESat-2, DEM based

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9242

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