Assessing streambed stability using D50-based stream power across contiguous U.S.

Authors: JHA, MANOJ - North Carolina A&t State University; ASAMEN, DAWIT - North Carolina A&t State University; ALLEN, PETER - Baylor University; Arnold, Jeffrey; White, Michael

Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2022
Publication Date: 11/12/2022
Citation: Jha, M.K., Asamen, D.M., Allen, P.M., Arnold, J.G., White, M.J. 2022. Assessing streambed stability using D50-based stream power across contiguous U.S. Water. 14:3646. https://doi.org/10.3390/w14223646.
DOI: https://doi.org/10.3390/w14223646

Interpretive Summary: Streams are in dynamic equilibrium with the environment and upstream conditions. When flow or sediment loads in a stream are altered the stream responds by degrading (downcutting) or aggrading (raising the base level), both of which can lead to adverse impacts on near channel structures. In this study we develop a screening tool to assess the streambed stability and apply this tool at the Physiographic Province Level. Blue Ridge and Pacific Border provinces showed high potential for downcutting. Deposition dominated streams are prominent in the Central Lowland, Great Plains and Coastal Plain, whereas the Colorado Plateaus and Wyoming Basin were found to have the highest percentage of stable channels. Comparison of channel erosion and deposition predictions using this tool and actual field calculated aggradation and degradation yielded in a 55% prediction accuracy. Headwater streams tended to have higher degradation potential.

Technical Abstract: Streambed aggradation and degradation are ways in which a stream will respond to changes in the amount of incoming flow and sediment loads. Several environmental and societal problems are attributed to channel bed adjustments. Stream power has been extensively used to discern dominant channel process and to establish threshold limits required to trigger channel modification. However, lack of comprehensive datasets prohibited the application on a regional scale. This study used a large dataset of streambed median grain size (D50) across the contiguous U.S. in conjunction with a screening tool to assess the streambed stability for channel erosion and deposition potential. Analysis at the Physiographic Province Level indicated that the major geomorphic changes are highly likely to occur in the Blue Ridge and Pacific Border provinces. Deposition dominated streams are prominent in the Central Lowland, Great Plains and Coastal Plain, whereas the Colorado Plateaus and Wyoming Basin were found to have the highest percentage of stable channels. Smoothed spatial maps of stream power indicated the prevalence of high stream power in the Northeast and Pacific Northwest regions of the U.S. Comparison of channel erosion and deposition predictions using the stream power map with actual field calculated aggradation and degradation results yielded in a 55% prediction accuracy. Further analysis based on the stream order revelated higher specific stream power associated with lower stream orders, with the maximum power value usually occurring closer to headwater streams.