The effect of a Macrocystis kelp forest on shoreward propagating surface gravity waves was measured. Observations were made over a 67-day period at four locations around a 350-m-wide kelp bed off Carlsbad, California. Instruments were located directly offshore and onshore of the kelp bed at depths of 13 m and 8 m, respectively, and at control stations at the same depths, but displaced 750 m alongshore, away from the kelp bed. The bathymetry between the offshore and onshore sites was gently sloping and featureless. The measured spectra, significant wave height, mean wave direction at peak frequency, and total radiation stress differed only slightly between the offshore kelp and control stations and were similar at the onshore sites. The similarity of the wave field at the onshore kelp and control sites shows that this typical southern California kelp bed, with an average density of about 10 plants per 100 m 2 , does not have a significant effect on waves. These measurements can be used to place upper bound...

Closure of "Effects of Southern California Kelp Beds on Waves"

Beach profile changes induced by surrogate Posidonia Oceanica: Laboratory experiments

Coastal populations around the world are at a greater risk of damage from coastal hazards due to the unprecedented rise of global climate change characterized by sea-level rise, longer and frequent droughts and floods, heightened cyclonic and storm surge activities. The narrow fringe of vegetated coastal habitats along the shores of continents mainly acts as a buffer for the impacts of rising sea levels and wave action. The losses from natural disasters like the 2004 Indian Ocean tsunami, Hurricane Katrina, and others have reached an all-time high, and the decision-makers now realize that coastal habitats have an important role to play in risk reduction. Though coastal vegetation, as a shore protection method, is sustainable, environment friendly, and cost-effective, its behavior with wave is very complex, especially because of the coupling between the waves and vegetation motion and is therefore, not completely understood. Numerical modelling approach, having based on more assumptions and field study, being uneconomical fomented the need for the study in the form of physical modelling. This paper focuses on figuring out the effect of vegetation on wave attenuation through an experimental approach. The wave flume of length 50 m, height 1 m, and width 0.71 m is used to study the characteristic behavior of submerged heterogeneous vegetation of varying width for wave heights ranging from 0.08 to 0.16 m with an increment of 0.02 m and wave periods 1.8 and 2 s in water depths of 0.40 and 0.45 m. Measurements of wave heights at locations along the vegetation were observed to quantify wave attenuation and its trend.

I. Mohit Babu

Papers

Experimental Investigations of Wave Height Attenuation by Submerged Artificial Vegetation