Anthropogenic Disturbances and Sand Bar Size Variations of Coastal Plain Rivers, USA

Authors: Joann Mossa*, University of Florida
Topics: Geomorphology, Anthropocene, Physical Geography
Keywords: fluvial geomorphology, sediments, sand bars, anthropogenic disturbances
Session Type: Paper
Day: 4/10/2018
Start / End Time: 8:00 AM / 9:40 AM
Room: Balcony K, Marriott, River Tower Elevators, 4th Floor
Presentation File: No File Uploaded

We investigate sand bars in selected central and eastern Gulf coastal plain rivers that have been subject to varied disturbances along the channel corridor, an upstream tributary, or on the basin’s uplands. Changes in individual bar sizes relate to the history of natural disturbances such as floods and droughts and anthropogenic disturbances including dredging and disposal, floodplain mining and local pit avulsions, land use changes and other human activities. Prior studies have related the size of sand bars flood pulses on large tributaries or on the main-stem river, to historical land-use changes, to floodplain sand and gravel mining activity including local avulsions or flooding-induced surface erosion over bare landscapes, to rapid channel migration and associated bank erosion, and to dredging and disposal of sediments in navigation channels. By collecting bar size data at different flow levels from digitizing photography in GIS, and evaluating over space and time, we use residuals from discharge-bar area bivariate graphs to better discern the role of anthropogenic disturbances in multiple coastal plain rivers. Findings provide useful information for evaluating legacy sediment, the effects of channel disturbance, and a framework for assessing aspects of the recovery of rivers from changes due to anthropogenic causes.

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