Experimental Study of Reduction of Solitary Wave Run-Up by Emergent Rigid Vegetation on a Beach

Abstract

Extensive studies have been carried out to study the performance of mangrove forests in wave height reduction. In this study, the reduction of the inundation and run-up of leading tsunami waves by mangrove forests was investigated through a series of laboratory experiments conducted in a long wave tank. The inundation and run-up were measured using a high speed CCD camera. Solitary waves were used to model the leading tsunami waves. Five vegetation models representing three forest densities and two tree distributions were examined on an impermeable sloping beach, and they were compared with the non-vegetated slope in view of wave reflection, transmission, and run-up. Results show that both incident wave height and run-up could be reduced by up to 50% when the vegetation was present on the slope. Dense vegetation reduced the wave transmission because of the increased wave reflection and energy dissipation into turbulence in vegetation. Normalized wave run-up on the beach decreased with the increase of both normalized incident wave height and forest density. Effect of forest density on the wave run-up on the sloping beach was further examined, and an empirical formula with the density incorporated was proposed. The study also highlighted the importance of tree distribution to wave interaction with vegetation on the slope when the forest density was unaltered, and run-up reduction difference between tandem and staggered arrangements of the trees could reach up to 20%.

Numerical Analysis on Influences of Emergent Vegetation Patch on Runup Processes of Focused Wave Groups

“…Effects of the open gap of the coastal vegetation on the runup of tsunami waves were analyzed by Thuy et al [55]. Later, influences of the vegetation density on the wave runup were discussed by Iimura et al [23] and Yao et al [56]. By applying the shallow water model, Tang et al [57] and Zhang et al [58] studied the wave runup and land flooding processes at the vegetated sloped beach.…”

Large eddy simulation modeling of tsunami-like solitary wave processes over fringing reefs

“…A tsunami is an extremely destructive natural disaster, which can be generated by earthquakes, landslides, volcanic eruptions and meteorite impacts. Tsunami damage occurs mostly in the coastal areas where tsunami waves run up or run down the beach, overtop or ruin the coastal structures, and inundate the coastal towns and villages (Yao et al, 2015). Some tropic and subtropical coastal areas vulnerable to tsunami hazards are surrounded by coral reefs, especially those in the Pacific and Indian oceans.…”

“…It is able to account for both nonlinear and dispersive effects at intermediate water level. At a laboratory scale, Boussinesq models combined with some semiempirical breaking wave and bottom friction models have been proven to be able to simulate the motions of regular waves (Skotner and Apelt, 1999;Yao et al, 2012), irregular waves (Nwogu and Demirbilek, 2010;Yao et al, 2016Yao et al, , 2019 and infragravity waves (Su et al, 2015;Su and Ma, 2018) over fringing reef profiles.…”

LES Modeling of Tsunami-like Solitary Wave Processes over Fringing Reefs

“…Tsunami is an extremely destructive natural disaster, which can be generated by earthquakes, landslides, volcanic eruptions, and meteorite impacts. Tsunami damage occurs mostly in the coastal areas where tsunami waves runup or rundown the beach, overtop or ruin the coastal structures, and inundate the coastal towns and villages (Yao et al, 2015). Some tropic and sub-tropic coastal areas vulnerable to tsunami hazards are surrounded by coral reefs, especially those in the Pacific and Indian Oceans.…”