How to Cite
Abstract
As the demand for nature-based coastal protection methods increases globally, there remains a stringent need to develop evidence-based design guidance for many of these methods and techniques. Anchored Large Woody Debris (LWD) has been used as an economical method of coastal protection for several decades and has, more recently, gained notoriety as a nature-based approach. Existing design guidance, however, is both limited and not significantly rooted in academic research. This paper presents results from the first experimental study related to coastal protection using LWD. Gravel beach response to various LWD configurations were tested at a large scale based on site characteristics and LWD design characteristics made by the authors during the previous field investigation phase of this research project. Tests were also conducted to assess experiment repeatability, sensitivity to test duration, sensitivity to wave height, wave period, and relative water level, and influence of log roughness. The LWD placement elevation relative to the still water level was found to be strongly linked to the beach morphological response and a theoretical relationship was developed between LWD elevation and sediment volume change. LWD design configurations which included LWD below the still water level, such as the Benched configuration, were found to be most effective at stabilizing the beach profile. To realize potential benefits of coastal protection using LWD, significant additional research is needed on the topic, including studies focused on how to best anchor LWD structures and a wider variety of parameters (hydrodynamic conditions and placement techniques).References
Atladottir, A. 2008. Experimental Investigation of Wave-Induced Morphological Changes of Gravel Beaches. Master’s Thesis. University of Ottawa. https://doi.org/https://doi.org/10.1002/ejlt.201200414
Bagnold, R.A. 1940. Beach Formation by Waves: Some Model Experiments in a Wave Tank. J. Inst. Civ. Eng., 15, 27–52. https://doi.org/10.1680/ijoti.1940.14279
Bilkovic, D.M., M.M. Michell, M.K. La Peyre, and J.D. Toft. 2017. Living Shorelines: The Science and Management of Nature-Based Coastal Protection. Taylor & Francis, Boca Raton, FL.
Bocchiola, D. 2011. Hydraulic characteristics and habitat suitability in presence of woody debris: A flume experiment. Advances in Water Resources, 34, 1304–1319. https://doi.org/10.1016/j.advwatres.2011.06.011
Braudrick, C.A., G.E. Grant, and J.A. Jones. 2001. Entrainment and deposition of large woody debris in streams: a flume experiment 41, 263–283.
Brennan, J., H. Culverwell, R. Gregg, and P. Granger, 2009. Protection of marine riparian functions in Puget Sound, Washington. Seattle, WA.
Buscombe, D., and G. Masselink. 2006. Concepts in gravel beach dynamics. Earth Science Review, 79, 33–52. https://doi.org/10.1016/j.earscirev.2006.06.003
de San Román-Blanco, B.L., T.T. Coates, P. Holmes, A.J. Chadwick, A. Bradbury, T.E. Baldock, A. Pedrozo-Acuña, J. Lawrence, and J. Grüne. 2006. Large scale experiments on gravel and mixed beaches: Experimental procedure, data documentation and initial results. Coastal Engineering, 53, 349–362. https://doi.org/10.1016/j.coastaleng.2005.10.021
Eamer, J.B.R., and I.J. Walker. 2010. Geomorphology Quantifying sand storage capacity of large woody debris on beaches using LiDAR. Geomorphology, 118, 33–47. https://doi.org/10.1016/j.geomorph.2009.12.006
Falkenrich, P., J.L. Wilson, I. Nistor, N. Goseberg, A. Cornett, and M. Mohammadian. 2021. Nature-Based Coastal Protection by Large Woody Debris as Compared to Seawalls: A Physical Model Study of Beach Morphology and Wave Reflection. Water, 13(15). https://doi.org/10.3390/w13152020
Finlayson, D. 2006. The Geomorphology of Puget Sound Beaches, Puget Sound Nearshore Partnership Technical Report 2006-02. https://doi.org/10.1111/jsbm.12106
Frandsen, J.B., F. Bérubé, R. Xharde, and O.G. Tremblay. 2015. Large Scale Experimental Storm Impact on Nourished Beach Using Cobble-Gravel-Sand Mix, in: Proceedings of the ASME 2015 34th International Conference on Ocean, Offshore, and Arctic Engineering, 1–10.
Gonor, J.J., J.R. Sedell, and P.A. Benner. 1988. What We Know About Large Trees in Estuaries, in the Sea, and on Coastal Beaches, in: From the Forest to the Sea, a Story of Fallen Trees, 83–112.
Grilliot, M.J., I.J. Walker, and B.O. Bauer. 2018. Airflow dynamics over a beach and foredune system with large woody debris. Geosciences, 8, 20. https://doi.org/10.3390/geosciences8050147
Heathfield, D.K., and I.J. Walker, 2011. Analysis of coastal dune dynamics, shoreline position, and large woody debris at Wickaninnish Bay, Pacific Rim National Park, British Columbia. Canadian Journal of Earth Science, 48, 1185–1198. https://doi.org/10.1139/E11-043
Heller, V. 2011. Scale effects in physical hydraulic engineering models. Journal of Hydraulic Research, 49, 293–306. https://doi.org/10.1080/00221686.2011.578914
Hilderbrand, R.H., D.A. Lemly, A.C. Dolloff, and K.L. Harpster. 1998. Design Considerations for Large Woody Debris Placement in Stream Enhancement Projects. North American Journal of Fisheries Management, 18, 161–167.
Horn, D., L. Li, D. Hornt, and L. Lit. 2006. Measurement and Modelling of Gravel Beach Groundwater Response to Wave Run-up: Effects on Beach Profile Changes. Journal of Coastal Research, 22, 1241–1249. https://doi.org/10.2112/06A-0006.1
Huff, S. 2015. Modeling the Influence of Large Woody Debris on Delta Morphology and Longshore Sediment Transport using the Brazos Delta. Rice University.
Hughes, S. 1993. Physical models and laboratory techniques in coastal engineering. Coastal Engineering, 7. World Scientific.
Hygelund, B., and M. Manga. 2003. Field measurements of drag coefficients for model large woody debris. Geomorphology, 51, 175–185.
Johannessen, J., A. Maclennan, A. Blue, J. Waggoner, S. Williams, W.J. Gerstel, R. Barnard, R. Carman, and H. Shipman. 2014. Marine Shoreline Design Guidelines.
Kail, J., D. Hering, S. Muhar, M. Gerhard, and S. Preis. 2007. The use of large wood in stream restoration: experiences from 50 projects in Germany and Austria. Journal of Applied Ecology. 1145–1155. https://doi.org/10.1111/j.1365-2664.2007.01401.x
Kennedy, D.M., and J.L.D. Woods. 2012. The influence of coarse woody debris on gravel beach geomorphology. Geomorphology. 159–160, 106–115. https://doi.org/10.1016/j.geomorph.2012.03.009
Kobayashi, N., B.S. Hicks, and J. Figlus. 2011. Evolution of gravel beach profiles. Journal of Waterways Ports, Coastal, and Ocean Engineering, 137, 258–262. https://doi.org/10.1061/(ASCE)WW.1943-5460.0000085
Lee, K.H., N. Mizutani, D.S. Hur, and A. Kamiya. 2007. The effect of groundwater on topographic changes in a gravel beach. Ocean Engineering, 34, 605–615. https://doi.org/10.1016/j.oceaneng.2005.10.026
Masselink, G. and I.L. Turner. 2012. Large-scale laboratory investigation into the effect of varying back-barrier lagoon water levels on gravel beach morphology and swash zone sediment transport. Coastal Engienering, 63, 23–38. https://doi.org/10.1016/j.coastaleng.2011.12.007
Murphy, E., A. Cornett, I. Nistor, and S. Baker. 2020. Modelling Transport and Fate of Woody Debris in Coastal Waters. Coastal Engineering Proceedings, 36, 1-1.
Perry, B., C. Rennie, A. Cornett, and P. Knox. 2018. Comparison of Large Woody Debris Prototypes in a Large Scale Non-flume Physical Model, in: E3S Web of Conferences. EDP Sciences, Ottawa, 1–8. https://doi.org/10.1051/e3sconf/20184005010
Pontee, N., S. Narayan, M.W. Beck, and A.H. Hosking. 2016. Nature-based solutions: lessons from around the world. Maritime Engineering, 169, 29–36.
Powell, K.A. 1990. Predicting Short Term Profile Response for Shingle Beaches, Report SR2 19. Wallingford, Oxfordshire.
Rafferty, M. 2017. Computational Design Tool for Evaluating the Stability of Large Wood Structures. Technical Note TN-103.2 27.
Sass, G. 2009. Coarse Woody Debris in Lakes and Streams. Encyclopedia of Inland Waters. https://doi.org/10.1016/B978-012370626-3.00221-0
Sutherland, J., and R. Soulsby. 2010. Guidelines for Physical Modelling of Mobile Sediments. Proceedings of Coastlab 2010. 15.
USACE. 2002. Coastal Engineering Manual Part II, Coastal Engineering Manual. https://doi.org/10.1093/intimm/dxs026
Van Der Meer, J.W. 1988. Rock Slopes and Gravel Beaches under Wave Attack. PhD Thesis. Delft University.
van Hijum, E. 1975. Equilibrium Profiles of Coarse Material under Wave Attack. Coastal Engineering. 939–957. https://doi.org/10.1093/oseo/instance.00076483
van Hijum, E., and K.W. Pilarczyk. 1982. Gravel Beaches: Equilibrium Profile and Longshore Transport of Coarse Material Under Regular and Irregular Wave Attack.
Wallerstein, N.P., C.V. Alonso, S.J. Bennett, and C.R. Thorne. 2001. Distorted froude-scaled flume analysis of large woody debris. Earth Surface Processes and Landforms, 26, 1265–1283. https://doi.org/10.1002/esp.271
Wilson, J.L., I. Nistor, and M. Mohammadian. 2019. Nature-based coastal protection using Large Woody Debris: What is it and does it work?. Climate-Resilient Coastal Natural Infrastructure Workshop. Halifax, NS. https://doi.org/10.13140/RG.2.2.12171.54564
Wilson, J.L., I. Nistor, M. Mohammadian, A. Cornett, and G.F. Lamont. 2020. Assessing the Legacy of Large Woody Debris as Coastal Protection in BC and Washington. Salish Sea Ecosystem Conference. Vancouver, BC. https://doi.org/10.13140/RG.2.2.33556.86406
Zelo, I., H. Shipman, and J. Brennan. 2000. Alternative Bank Protection Methods for Puget Sound Shorelines. Olympia, WA.
This work is licensed under a Creative Commons Attribution 4.0 International License.
Copyright (c) 2023 Jessica Wilson, Pauline Falkenrich, Ioan Nistor, Andrew Cornett, Abdolmajid Mohammadian