NEW INSIGHTS ON USING SCALED MARSH PLANT SURROGATES FOR WAVE ATTENUATION

Abstract

It has been widely demonstrated in literature that coastal marshes provide positive ecosystem services related to coastal protection, including wave attenuation, storm surge reduction, and erosion prevention (Moller et al., 2014; Wang et al., 2021; Paul and Kerpen, 2021). Physical modelling presents a useful tool for investigating the coastal protection function provided by marsh vegetation in a controlled, repeatable environment, to inform design of nature-based coastal protection strategies, or “nature-based solutions” (NBS). To date, physical modelling studies have been used to investigate the influence of plant biophysical parameters (stem width, stem height, stem flexibility) and hydrodynamic conditions on wave attenuation (e.g., Augustin et al., 2009; Anderson and Smith, 2014; Moller et al., 2014; Ozeren et al., 2014; van Veelen et al., 2020). Such studies have predominantly used surrogate vegetation due to the logistical challenges and facility requirements associated with live plant experiments. Furthermore, most studies have been performed at or near full-scale to reduce uncertainties and scale effects associated with downscaling vegetation, particularly where Reynolds number similarity cannot be preserved (Blackmar et al., 2014). To address existing knowledge gaps related to physical modelling of marsh vegetation at small-scale, experiments were conducted in a 63 m long by 1.22 m wide wave flume at the National Research Council of Canada’s Ocean, Coastal and River Engineering Research Centre, Ottawa, in collaboration with the University of Ottawa and the Institut National de la Recherche Scientifique, Quebec City.