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United States Department of Agriculture

Agricultural Research Service

Research Project: Technologies for Managing Water and Sediment Movement in Agricultural Watersheds

Location: Watershed Physical Processes Research Unit

Title: Laboratory measurements of wave attenuation through model and live vegetation

Authors
item Ozeren, Yavuz -
item Wren, Daniel

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: August 25, 2011
Publication Date: August 12, 2013
Citation: Ozeren, Y. and Wren, D. G. Laboratory measurements of wave attenuation through model and live vegetation. In: Coastal Hazards (pp. 45–56). American Society of Civil Engineers. doi:10.1061/9780784412664.005. 2013.

Interpretive Summary: Hurricanes and tropical storms often cause severe damage and loss of life in coastal areas. It is widely recognized that wetlands along coastal fringes reduce storm surge and waves. The potential role and primary mechanisms of wave mitigation by wetland vegetation are not fully understood. Knowledge of the reduction in wave height and energy as the waves encounter obstacles such as marsh grasses is essential for assessing the ability of vegetation to limit wave damage. It is also important for coastal marsh restoration design, where the width of the restored or established marsh may be based how the waves will be reduced as they cross the marsh. The goal of this study was to quantify the reduction in wave height and energy as they relate to vegetation type, density, and height through laboratory experiments. The properties of waves passing through rigid and flexible model vegetation as well as live Spartina alterniflora and Juncus romerianus were measured. An automated system was developed and used to generate regular and random waves and to record time series of water surface elevation. A technique was developed for extracting the water surface profile through the vegetation field from images recorded with a consumer grade digital video camera. The new method was also tested for wave setup measurements along a plane sloping beach.

Technical Abstract: Surge and waves generated by hurricanes and tropical storms often cause severe damage and loss of life in coastal areas. It is widely recognized that wetlands along coastal fringes reduce storm surge and waves. Yet, the potential role and primary mechanisms of wave mitigation by wetland vegetation are not fully understood. Knowledge of wave attenuation is essential for assessing the ability of vegetation to limit wave damage. The goal of the work reported here was to use a laboratory wave flume to quantify the attenuation of waves as a function of vegetation type, density, and height. The properties of waves passing through rigid and flexible model vegetation as well as live Spartina alterniflora and Juncus romerianus were measured. An automated system was developed and used to generate regular and random waves and to record time series of water surface elevation. A technique was developed for extracting the water surface profile through the vegetation field from images recorded with a consumer grade digital video camera. The new method was also tested for wave setup measurements along a plane sloping beach.

Last Modified: 9/20/2014
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