Quantifying the temporal dynamics of wood in large rivers: field trials of wood surveying, dating, tracking, and monitoring techniques

Authors

  • B.J. MacVicar,

    Corresponding author
    1. Department of Civil and Environmental Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
    • Department of Civil and Environmental Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
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  • H. Piégay,

    1. CNRS UMR 5600 – Environnement Ville et Société, University of Lyon, Site of École Normale Supérieure – LSH, 15 Parvis René Descartes, BP 7000, 69342, Lyon cedex 07, France
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  • A. Henderson,

    1. Division of Planning and Local Assistance, Northern District, California Department Of Water Resources, 2440 Main Street, Red Bluff, California, 96080-2356, USA
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  • F. Comiti,

    1. Faculty of Science and Technology, Free University of Bozen-Bolzano, via Leonardo da Vinci 7, 39100 Bozen-Bolzano, Italy
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  • C. Oberlin,

    1. CNRS UMR 5138, Archéométrie et Archéologie, Université Claude Bernard Lyon 1, 40 boulevard Niels Bohr, 69622 Villeurbanne Cedex, France
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  • E. Pecorari

    1. Department of Environmental Science, Ca' Foscary University, Santa Marta – Dorsoduro 2137 30121 Venezia-Venice, Italy
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Abstract

Wood plays an important role in stream ecology and geomorphology. Previous studies of wood in rivers have quantified spatial distributions but temporal dynamics remain poorly documented. The lack of such data is related to limitations of existing methods, especially when applied to large rivers. Five techniques are field-tested to assess their utility for quantifying the temporal dynamics in rivers: repeated high-resolution aerial surveys, the measurement of wood physical characteristics as proxies for 14C dating, passive and active radio frequency identification (RFID) tags, radio transmitters, and video. The spatial distribution of wood is surveyed using aerial imagery with a resolution finer than 0·10 m. The estimation of temporal trends by repeated aerial-based surveys needs to consider vegetation growth and hiding. Wood residence times can be calculated using 14C analysis, but the assessment of wood physical characteristics including decay status and wood density offers a cheaper, if less accurate, alternative. Wood resistance to penetration is tested but results are not significant. Radio transmitters are reliable for multi-year (∼5 year) surveys and can be detected at 800 m. Passive RFID tags are limited by a read range of 0·30 m but are reliable for longer term (>5 year) studies. Active RFID tags combine a moderate read range (10–300 m) and low cost with in-flood detection but require more testing. Video monitoring of wood passing on the surface of a river is successfully implemented. For a single flood on the Ain River (France), wood transport rates are an order of magnitude higher on the rising limb of the hydrograph than on the falling limb. Overall, the techniques improve the ability to gather the data needed to understand wood transfer processes and calibrate budgets of wood in rivers. Copyright © 2009 John Wiley & Sons, Ltd.

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