Influence of bank stabilization on floodplain sediment and phosphorus storage

Date: 
Aug 2021

Issue

Eroding river banks are frequently stabilized with rock, concrete or wood when infrastructure or property is threatened. There is also growing interest in using bank stabilization as a way to reduce nutrient loading from bank erosion. However, little is known about the impacts of bank stabilization on the sediment deposition process on opposing point bars and the adjacent floodplain, whose dynamics are closely coupled with bank erosion. If arresting bank erosion also reduces sediment and phosphorus deposition and storage elsewhere, the nutrient reduction benefits of streambank stabilization may be less than expected.

Objective

Researchers plan to compare the sediment and P concentrations of eroded and deposited sediment in five stabilized and five unstabilized river bends in the Nishnabotna River watershed to determine whether bank stabilization has any systematic impact on reach-scale sediment and P storage.

Approach

Aerial imagery and LiDAR elevation data will be used to estimate the total volumes of sediment eroded and deposited from each stabilized and unstabilized bend. Researchers will then map and sample different sediment types on each point bar and adjacent floodplain to characterize both the sediment eroded and deposited and its P concentration. The results will be compared to determine whether sediment and P storage on point bars and adjacent floodplains is reduced in bends with bank stabilization structures.

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