Wave Attenuation by Emergent Wetland Vegetation

Though there is agreement that shoreline and aquatic plants are an integral part of more environmentally compatible shore protection techniques, there is little data or design information available to ensure successful implementation. The value of shoreline wetlands has become increasingly recognized. One of the important functions of shoreline wetland vegetation is its ability to absorb wave energy; however, considerable questions regarding the magnitude and importance of this process exist. In order to address these concerns, a research study was undertaken to assess, qualitatively and quantitatively, wave attenuation by emergent wetland plants. A Lake Ontario shoreline wetland was monitored over a 3 year period and an extensive series of complementary laboratory flume tests were performed. The laboratory experiments were conducted using irregular waves and live vegetation taken from the field site. Several key parameters and trends, with respect to wave attenuation and emergent wetland vegetation, were identified. A pair of empirically based equations was developed that predicted wave attenuation through the emergent, freshwater, wetland plants.