Restoration impacts on distributary slough floodplain inundation and connectivity

Inundation is a key driver of floodplain ecosystem health, governing nutrient exchange, habitat connectivity, and sediment dynamics. However, limited research has quantified how ecological restoration influences these natural processes at a system-wide scale. This study quantifies changes in floodplain inundation within the slough section of the Apalachicola River, Florida, evaluating the impacts of ecological restoration on hydrological and geomorphic dynamics. Employing the HEC-RAS 2D model, this research utilizes a Digital Elevation Model (DEM) created from LiDAR data collected in 2021, providing high-resolution topographic details essential for accurate flood simulation. River flow data from the same year complements the DEM, enabling precise analysis of pre- and post-restoration conditions. The modeling results predicted a substantial improvement in floodplain connectivity: the flow required to inundate substantial portions of the floodplain decreased from 500 m³s⁻¹ to 350 m³s⁻¹ after restoration efforts. Furthermore, the area experiencing significant inundation increased by 15 %, highlighting an enhancement in ecological functionality. The duration of inundation has also extended, allowing for longer periods of water retention, which is critical for supporting riparian habitats. Model validation yielded a Nash-Sutcliffe Efficiency of 0.95, affirming the robustness of the simulations. These findings underscore the potential of the restoration in enhancing floodplain functionality, with increased inundation areas and improved water and sediment dynamics.