Assessing the impact of dam construction on river disconnectivity in a large coastal plain river

Authors: Amobichukwu Amanambu*, University of Florida, Joann Mossa, University of Florida, Yin-Hsuen Chen, University of Florida
Topics: Geomorphology, Landscape, Water Resources and Hydrology
Keywords: (dis)connectivity; River, Dams, Discharge, HRU, Morphology
Session Type: Virtual Paper
Day: 4/8/2021
Start / End Time: 1:30 PM / 2:45 PM
Room: Virtual 3
Presentation File: No File Uploaded

Globally, human influences on rivers and their ecosystems have become a subject of rising interest because of the negative feedback from increasing river fragmentation or disconnectivity. Dams cause flow and riverbed alterations with river ecosystem damage due to flow regulation, sediment trapping, and river disconnectivity. This research focuses on the Apalachicola River, a large coastal plain river with a wide floodplain comprised of many sloughs and tributaries. Jim Woodruff Lock and Dam is one of the primary causes of increasing disconnectivity and floodplain drying. Stage levels have been declining since the mid-1950s due to both degradation and increasing water use upstream. The study used river connectivity index to evaluate the dam's aggregate impact on river connectivity between 1960 and 2010. Discharge data from 1928 to 2020 was used to quantify temporal changes in river flow. The effects of the dam on channel morphology are evident ~35 km downstream. Specifically, the workflow involved dividing the river basin into the hydrologic response unit (HRU) to simulate a representative response to the river regulation. The study also examined the degree of landscape connectivity at the upper part of the basin using graph theory. With increasing alteration caused by the dam, the result reveals substantial river disconnectivity in some parts of the tributaries of the Apalachicola River, highlighting variation in the spatial pattern of disconnectivity. The result of this study shows that understanding river connectivity is crucial for river functioning and sustainable management policies.

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