107-17 Automated Delineation of Secondary Channels in a Low-Relief Floodplain Using LiDAR-Derived Terrain Metrics, Apalachicola River, USA

Session: Sedimentary Geology Division/SEPM Student Research Poster Competition: Dynamics of Stratigraphy and Sedimentation

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Abstract:

In alluvial rivers, flow outside the main channel is often organized into an intricate network of secondary channels across the floodplain. The Apalachicola River, a biologically diverse, low-gradient system in the southeastern United States, relies on these secondary channels to support critical spawning habitats for aquatic organisms, sustain wetlands, and transport nutrients to downstream estuaries. Despite their ecological importance, mapping secondary channels across low-relief, densely vegetated floodplain terrain has historically been difficult. Now, with the availability of high-resolution Light Detection and Ranging (LiDAR) data, it is possible to detect these subtle floodplain features using digital elevation models (DEMs). This study evaluates two automated extraction techniques–based on analysis of topographic curvature (Laplacian of elevation) and mathematical morphology (bottom-hat transformation)–for identifying secondary channels in a LiDAR-derived DEM of the Apalachicola River floodplain. To assess accuracy, we compare the results of each automated method against a set of reference channels manually delineated using a River Elevation Model (REM) for enhanced visualization. This research aims to inform the development of reproducible, accurate workflows for delineating secondary channels in low-relief, densely vegetated floodplains. Understanding the spatial arrangement of these channels will provide a foundation for future studies on the transport of water, sediment and nutrients within the topographically complex floodplains of large alluvial river systems.

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

doi: 10.1130/abs/2025AM-10320

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