Laboratory Investigations on the Effect of Fragmentation and Heterogeneity of Coastal Vegetation in Wave Height Attenuation
It has long been known that “bio-shields” do function as a sustainable solution for preserving our coasts. The presence of gaps in the “bio-shield”, that is, the forest cover, referred to as patchiness, is a common phenomenon in natural habitats. Various anthropogenic and natural causes can result in such gaps in coastal forests. This paper presents the results of a physical model investigation carried out with a fragmented heterogeneous vegetation model in a wave flume 50 m long, 0.71 m wide and 1.1 m deep. The heterogeneous meadow is modelled as a combined body of artificial submerged seagrass, rigid vegetation and emergent vegetation. To study the effect of fragmentation in vegetation, transverse gaps of varying widths are introduced in the heterogeneous model. The material used for modelling is polyethylene and nylon. The test runs were carried out with monochromatic waves of heights ranging from 0.08 to 0.16 m in water depths of 0.40 and 0.45 m, and wave periods 1.8 and 2 s. The wave height measurements at different locations within the vegetated meadow exhibit an exponential decay of wave heights. The presence of gaps in vegetation does not have a significant effect on wave height reduction. However, the experimental study revealed that heterogeneous vegetation showed a great promise leading to considerable wave attenuation, thus offering a good level of protection to life and property on the leeside.
KeywordsCoastal vegetation Heterogeneity Fragmentation Gap Wave attenuation
- 2.Jayakumar S, Ilangovan D, Naik KA, Gowthaman R, Tirodkar G, Naik GN, Ganeshan P, Mani Murali R, Michael GS, Ramana MV, Bhattacharya GC (2005) Run-up and inundation limits along southeast coast of India during the 26 December 2004 Indian Ocean tsunami. Curr Sci 88(11):1741–1743Google Scholar
- 5.Asano T, Deguchi H, Kobayashi N (1992) Interaction between water waves and vegetation. In: Proceedings of 23rd international conference on coastal engineering, Venice, Italy, pp 2710–2723Google Scholar
- 11.Hogarth PJ (2015) The biology of mangroves and seagrasses. Oxford University PressGoogle Scholar