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AGU: Water Resources Research

 

Keywords

  • river restoration
  • gravel augmentation
  • sediment pulse
  • sediment transport
  • gravel bed river
  • dams

Index Terms

  • Biogeosciences: Restoration
  • Hydrology: Dams
  • Hydrology: Eco-hydrology
  • Hydrology: Geomorphology: fluvial
  • Hydrology: Sediment transport

Abstract

WATER RESOURCES RESEARCH, VOL. 45, W08439, 14 PP., 2009
doi:10.1029/2008WR007346

Translation and dispersion of sediment pulses in flume experiments simulating gravel augmentation below dams

Leonard S. Sklar

Department of Geosciences, San Francisco State University, San Francisco, California, USA

Jessica Fadde

Department of Geosciences, San Francisco State University, San Francisco, California, USA

Stillwater Sciences, Berkeley, California, USA

Jeremy G. Venditti

Stillwater Sciences, Berkeley, California, USA

Department of Earth and Planetary Sciences, University of California, Berkeley, California, USA

Peter Nelson

Department of Earth and Planetary Sciences, University of California, Berkeley, California, USA

M. Aleksandra Wydzga

Department of Earth Science, University of California, Santa Barbara, California, USA

Yantao Cui

Stillwater Sciences, Berkeley, California, USA

William E. Dietrich

Department of Earth and Planetary Sciences, University of California, Berkeley, California, USA

The effectiveness of gravel augmentation as a river restoration strategy depends on the extent and duration of the topographic and bed texture changes created by the pulse of added sediment. Previous work has emphasized the strong tendency for natural sediment waves to propagate primarily by dispersion; however, pulse translation may occur for gravel additions to armored channels downstream of dams where added sediments are finer than the preexisting bed material. Here we report results of a laboratory investigation in which we created an immobile, armored bed and documented the spatial and temporal evolution of the bed topography and bed texture in response to gravel pulses of various volumes and grain sizes. The introduced sediment waves evolved by a combination of translation and dispersion, with a significant translational component. Pulse translation and dispersion can be readily discerned on a graph of the time evolution of the downstream cumulative distribution of elevation differences from the preexisting bed topography. Translation was most evident for smaller volumes of added sediment. Pulses of finer-grained gravel moved through the flume more rapidly, resulting in a larger magnitude but shorter duration of bed fining. More work is needed to understand the influence of bar-pool topography and flow magnitude and duration before the grain size and volume of gravel additions can be selected to achieve optimal patterns of pulse propagation.

Received 7 August 2008; accepted 2 June 2009; published 28 August 2009.

Citation: Sklar, L. S., J. Fadde, J. G. Venditti, P. Nelson, M. A. Wydzga, Y. Cui, and W. E. Dietrich (2009), Translation and dispersion of sediment pulses in flume experiments simulating gravel augmentation below dams, Water Resour. Res., 45, W08439, doi:10.1029/2008WR007346.

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