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Journal ArticleDOI

Effect of vegetation on run-up and wall pressures due to cnoidal waves

08 Jul 2011-Journal of Hydraulic Research (Taylor & Francis)-Vol. 49, Iss: 4, pp 562-567

Abstract: A comprehensive experimental investigation was carried out to understand the effect of vegetation in attenuating run-up over a plane slope of 1 : 30 due to the propagation of cnoidal waves. Two different types of vegetation configurations, namely tandem and staggered, are considered. Dynamic pressures exerted along a vertical wall fronted by these two vegetation types were measured, and the typical variation of dimensionless peak pressures for different relative depths of submergence of the pressure ports is reported as a function of dimensionless parameters involving the vegetation and wave characteristics. Further, typical results on the variation of the dimensionless peak run-up versus the surf similarity parameter only for the staggered configuration are also herein reported. Finally, the percentage reduction in wave run-up and pressures on the wall due to the presence of wall fronted by vegetation are reported.
Topics: Iribarren number (54%), Vegetation (pathology) (53%), Cnoidal wave (51%), Wave propagation (50%)
Citations
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Journal ArticleDOI
Abstract: Experimental investigation has been done to access turbulence characteristics just above the sparse flexible submerged vegetation zone in open-channel flow. The experimentation has been done in a tilting flume with bed covered by artificial vegetation and arranged in a regular staggered configuration. The applicability of log law is analysed above the vegetated canopy. Turbulent parameters such as velocity profiles, Reynolds stresses, turbulent intensities, quadrant analysis, turbulent production and diffusion, dissipation and stream power have been appraised to understand the hydrodynamics of vegetated channel. Results show that the log law is valid above the canopy of submerged vegetation with decreased Von-Karman constant. Maximum value of turbulent intensities and Reynolds stresses has been found above the canopy. Quadrant analysis shows that sweeps and ejections events are more dominating factors in submerged vegetated channel.

3 citations


Cites background from "Effect of vegetation on run-up and ..."

  • ...Sundar et al. (2011) have examined the effect of vegetation on run-up and wall pressures due to cnoidal waves....

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Book ChapterDOI
01 Jan 2019-
Abstract: Coastal vegetation is a soft solution for protecting the coast from the action of waves by attenuating the wave height and reducing the energy of the waves. Effect of wave height attenuation as a result of the presence of emerged coastal vegetation is studied numerically by resolving the Reynolds-averaged Navier–Stokes (RANS) equations. A three-dimensional numerical wave tank model is simulated using an open source computational fluid dynamics (CFD) software REEF3D, and wave attenuation due to emerged coastal vegetation is determined. An artificial, rigid, emerged vegetation for a length of 2 m is developed in a numerical wave tank of REEF3D. The model is tested for regular waves of height 0.08, 0.12, and 0.16 m and wave periods of 1.8 and 2 s in a water depth of 0.40 and 0.45 m. The wave heights are measured at different locations along the vegetation meadow at 0.5 m intervals. The devolved numerical model is corroborated by comparing the obtained numerical results with the experimental results as reported by John et al. (Experimental investigation of wave attenuation through artificial vegetation meadow, ISH—HYDRO, [1]). The numerically obtained results are concurrent with the experimental results.

2 citations


Book ChapterDOI
01 Jan 2018-
Abstract: Coastal vegetation can protect people and property from erosion and flooding, potentially providing a solution for conservation and development. Recently, there has been a substantial interest in the ability of natural vegetation to protect people and infrastructure from storm, wind, and wave damage. These ecosystem services provide new and powerful reasons for conservation of coastal habitats and may represent solutions that balance conservation and development. Since the costs of installing hard structures for coastal protection are very high; strong negative public reaction to rock emplacements along the coast often aggravate the problem; research in the field of soft measures of coastal protection is important which highlights the need and importance of a sustainable, environment friendly, and cost efficient solution such as coastal or beach vegetation. This paper tries to bring out the effect of artificial emergent vegetation of meadow widths 1 and 2 m on wave run up through an experimental study. The tests were carried out with emergent vegetation placed on the bed of a 50 m long wave flume. For wave heights ranging from 0.08 to 0.16 m at an interval of 0.02 m and wave periods ranging from 1.4 to 2 s in water depths of 0.40 and 0.45 m, measurements of wave run up over the beach slope were observed.

1 citations


Book ChapterDOI
01 Jan 2018-
Abstract: 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.

1 citations


Journal ArticleDOI
01 Sep 2021-Ocean Engineering
Abstract: The sediment transport phenomenon is considered to be an important factor in improving coastline hydraulic performance. This research studied the effects of long waves as simulated solitary waves on the sediment transport to estimate the sediment transport rate in different coastal forest cover (CFC) densities. To examine how trees altered the wave characteristics, artificial trees were used experimentally to simulate the aligned and staggered configurations in totally 32 cover densities and 3 different wave heights. Results revealed that the CFC could averagely reduce the total sediment transport rate by up to 41.18% (in the densest case by 54% and 45% in staggered and aligned configurations, respectively, compared with the no-CFC case). The optimum density limit with maximum reduction effect was determined as 40–50% for the staggered and 70–80% for the aligned pattern. The configuration effects on the CFC efficiency were also investigated and showed the superiority of the zigzag configuration over the aligned arrangement. This study also used the laboratory data to develop two equations for calculating the sediment transport rate in the presence of coastal cover.

1 citations


References
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Journal ArticleDOI
Costas E. Synolakis1Institutions (1)
Abstract: This is a study of the runup of solitary waves on plane beaches. An approximate theory is presented for non-breaking waves and an asymptotic result is derived for the maximum runup of solitary waves. A series of laboratory experiments is described to support the theory. It is shown that the linear theory predicts the maximum runup satisfactorily, and that the nonlinear theory describes the climb of solitary waves equally well. Different runup regimes are found to exist for the runup of breaking and non-breaking waves. A breaking criterion is derived for determining whether a solitary wave will break as it climbs up a sloping beach, and a different criterion is shown to apply for determining whether a wave will break during rundown. These results are used to explain some of the existing empirical runup relationships.

811 citations


Journal ArticleDOI
George F. Carrier1, H. P. Greenspan1Institutions (1)
Abstract: In this paper, we investigate the behaviour of a wave as it climbs a sloping beach. Explicit solutions of the equations of the non-linear inviscid shallow-water theory are obtained for several physically interesting wave-forms. In particular it is shown that waves can climb a sloping beach without breaking. Formulae for the motions of the instantaneous shoreline as well as the time histories of specific wave-forms are presented.

678 citations


"Effect of vegetation on run-up and ..." refers background in this paper

  • ...Carrier and Greenspan (1958) solved the shallow water equations analytically by obtaining solutions for the prediction of the long wave run-up over smooth plane beaches....

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Book
01 Mar 1987-
Abstract: The subject of hydrodynamics applied to offshore structures is vast. The topics covered in this book aim to help the reader understand basic principles while at the same time giving the designer enough information for particular designs. Thus, results are given with derivations, and applications are discussed with the aid of examples, with an overview of the advantages and limitations of the method involved. This makes the book suitable as a text for undergraduate and graduate students specializing in offshore and ocean engineering. In addition, the final results, including tables and illustrations may be referenced directly without going through detailed derivations. They can therefore be used by design and applications engineers involved in offshore structure design. This title also introduces various types of offshore structures with reference to actual installations in various parts of the world. It describes wave mechanics and how to choose wave theories and design waves. After a choice of design wave is made, the author describes how this wave is used to obtain forces on a fixed offshore structure. If the structure is allowed to move, various methods of obtaining the motions of the structure are given. The short- and long-term responses are derived and different methods are described. The use of model tests to verify these methods at each step is shown.

621 citations


"Effect of vegetation on run-up and ..." refers methods in this paper

  • ...Considering the drag/inertia force regime (Chakrabarti 1983), the corresponding diameters for the exposed vegetal stems were determined....

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Journal ArticleDOI
Abstract: A study conducted after the 26th of December 2004 tsunami in 18 coastal hamlets along the south-east coast of India reiterates the importance of coastal mangrove vegetations and location characteristics of human inhabitation to protect lives and wealth from the fury of tsunami. The tsunami caused human death and loss of wealth and these decreased with the area of coastal vegetation, distance and elevation of human inhabitation from the sea. Human inhabitation should be encouraged more than 1 km from the shoreline in elevated places, behind dense mangroves and or other coastal vegetation. Some plant species, suitable to grow in between human inhabitation and the sea for coastal protection, are suggested.

590 citations


"Effect of vegetation on run-up and ..." refers background in this paper

  • ...The dominant role of vegetation to reduce the inundation distance and run-up during the ingress of great Indian Ocean tsunami of 2004 is reported by Kathiresan and Rajendran (2005)....

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  • ...distance and run-up during the ingress of great Indian Ocean tsunami of 2004 is reported by Kathiresan and Rajendran (2005). The studies of Mascarenhas and Jayakumar (2008) indicate that large stretches of the coast of Tamil Nadu (South East...

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Journal ArticleDOI
Abstract: A field study of the tidal currents, cohesive sediment dynamics and transport of organic carbon in a highly vegetated mangrove swamp was carried out at Middle Creek, Cairns, Australia. The interaction of tidal currents and the vegetation generated jets, eddies and zones of stagnant waters which were numerically modelled. A high value of the Manning friction coefficient (n=0·1) was derived by the dense vegetation. About 80% of the suspended sediment brought in from coastal waters at spring flood tide was trapped in the mangroves, corresponding to about 10–12 kg of sediment m−1creek length/spring tide, resulting in a rise of the substrate by about 0·1 cm year−1. The selective trapping of clay was caused by flocculation of the finer particles in the mangroves. There was an indication of a slight inwelling of organic carbon. Creek water was readily differentiated from mangrove water by large differences in the molecular weight distribution of the dissolved organic carbon.

438 citations


"Effect of vegetation on run-up and ..." refers background in this paper

  • ...Through experimental studies, Furukawa et al. (1997) demonstrated that the wave dissipation depends on the forest density and the diameter of the tree trunks....

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