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Riparian Corridor Recovery from Dredging, Apalachicola River, Florida

Authors: Joann Mossa*, University of Florida
Topics: Geomorphology, Biogeography, Water Resources and Hydrology
Keywords: biogeomorphology, fluvial geomorphology, vegetative recovery, dredging impacts, passive restoration, floodplains
Session Type: Paper
Presentation File: No File Uploaded

Anthropogenic impacts in large rivers are widely studied, but studies of recovery once a disturbance has stopped are uncommon. This study examines the biogeomorphic recovery of a 60-km river corridor from River Mile 36 to 85 on the Apalachicola River, Florida following the cessation of dredging and disposal in 2002. This failed navigation project involving decades of dredging caused vegetation losses, river widening and increased point bar areas. We used paired sets of imagery, earlier and later in the recovery process, at two different flow levels (~30th and 1st percentile) to assess bar-by-bar and overall land cover change and their spatial variations. Overall, most bars shrank due to vegetation gains; these gains were compensated by water and sand bar losses. In total, colonization by trees during the 10-year passive recovery period represents ~15% of dredge-related vegetation losses in the riparian corridor. Because higher stage variations upstream make it harder for plants and seedlings to establish, the lower portion of the study reach recovered better than the upper half. As parts of the river are healing, reduced channel capacity from narrowing and tree growth will benefit the floodplain. Yet, the river corridor continues to experience problems from decreased flow inputs and the legacy of the navigation project. As elsewhere, understanding of a river’s biogeomorphology, hydrology, and disturbance history can help in selecting appropriate recovery metrics to further advance the understanding and management of disturbed floodplains.

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