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Article

The Straightening of a River Meander Leads to Extensive Losses in Flow Complexity and Ecosystem Services

1
Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
2
Department of Environmental Resources Engineering, College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210, USA
*
Author to whom correspondence should be addressed.
Water 2020, 12(6), 1680; https://doi.org/10.3390/w12061680
Received: 13 April 2020 / Revised: 6 June 2020 / Accepted: 8 June 2020 / Published: 11 June 2020
(This article belongs to the Special Issue A Systems Approach for River and River Basin Restoration)
To assist river restoration efforts we need to slow the rate of river degradation. This study provides a detailed explanation of the hydraulic complexity loss when a meandering river is straightened in order to motivate the protection of river channel curvature. We used computational fluid dynamics (CFD) modeling to document the difference in flow dynamics in nine simulations with channel curvature (C) degrading from a well-established tight meander bend (C = 0.77) to a straight channel without curvature (C = 0). To control for covariates and slow the rate of loss to hydraulic complexity, each of the nine-channel realizations had equivalent bedform topography. The analyzed hydraulic variables included the flow surface elevation, streamwise and transverse unit discharge, flow velocity at streamwise, transverse, and vertical directions, bed shear stress, stream function, and the vertical hyporheic flux rates at the channel bed. The loss of hydraulic complexity occurred gradually when initially straightening the channel from C = 0.77 to C = 0.33 (i.e., the radius of the channel is three-times the channel width), and additional straightening incurred rapid losses to hydraulic complexity. Other studies have shown hydraulic complexity provides important riverine habitat and is positively correlated with biodiversity. This study demonstrates how hydraulic complexity can be gradually and then rapidly lost when unwinding a river, and hopefully will serve as a cautionary tale. View Full-Text
Keywords: river engineering; meander bend; CFD simulation; hydraulic complexity river engineering; meander bend; CFD simulation; hydraulic complexity
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MDPI and ACS Style

Zhou, T.; Endreny, T. The Straightening of a River Meander Leads to Extensive Losses in Flow Complexity and Ecosystem Services. Water 2020, 12, 1680. https://doi.org/10.3390/w12061680

AMA Style

Zhou T, Endreny T. The Straightening of a River Meander Leads to Extensive Losses in Flow Complexity and Ecosystem Services. Water. 2020; 12(6):1680. https://doi.org/10.3390/w12061680

Chicago/Turabian Style

Zhou, Tian, and Theodore Endreny. 2020. "The Straightening of a River Meander Leads to Extensive Losses in Flow Complexity and Ecosystem Services" Water 12, no. 6: 1680. https://doi.org/10.3390/w12061680

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