Stream Bank Sediment and Phosphorus Storage

Stream bank

Title: Influence of bank stabilization on floodplain sediment and phosphorus storage

Location: Nishnabotna River, IA

Time Period: 2021 - Present

Research Team: Peter Moore and Tom Isenhart

Project Description: 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 adjacent floodplain, whose dynamics are closely coupled with bank erosion. If arresting bank erosion also reduces sediment and P deposition and storage elsewhere, the nutrient reduction benefits of streambank stabilization may be less than expected. We are comparing the sediment and P concentrations of eroded and deposited sediment in five stabilized and five un-stabilized river bends in the Nishnabotna River watershed to determine whether bank stabilization has any systematic impact on reach-scale sediment and P storage. We are using aerial imagery and LiDAR elevation data to estimate the total volumes of sediment eroded and deposited from each stabilized and un-stabilized bend. We’re also mapping and sampling different sediment types on each point bar and adjacent floodplain to characterize both the sediment eroded and deposited and its P concentration. We’ll compare the results to determine whether sediment and P storage on point bars and adjacent floodplains is reduced in bends with bank stabilization structures.


Funders: Iowa Nutrient Research Center

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