Individual wave overtopping volumes on mound breakwaters in breaking wave conditions and gentle sea bottoms

Damage to coastal structures and surrounding properties from wave overtopping in extreme events is expected to be exacerbated in future years as global sea levels continue to rise and the frequency of extreme meteorological events and storm surges increases.&#160; Approaches for protecting our coastal areas have traditionally relied on the development and ongoing maintenance of &#8216;hard&#8217; defences. &#160;However, the longer-term sustainability of coastal flood management that is underpinned by such defences is increasingly being questioned both in terms of dealing with climate change and in the environmental/ ecological consequences and associated losses of biodiversity that comes with these structural defence lines in coastal areas.The term 'nature-based' has emerged in recent years to describe biomimicry-based engineered interventions in coastal defences. For example, the addition of artificial water-filled depressions on coastal structures e.g. &#8216;vertipools&#8217; on seawalls and the use of &#8216;drill-cored rock pools in intertidal breakwaters that enhance biodiversity and species richness on sea defence surfaces and in adjacent coastal zones. While the ecological benefits of such interventions are increasingly being investigated, the additional roughness they bring to sea defences and the role of this roughness in wave energy dissipation and in the mitigation of wave overtopping remains less well studied.Here we investigate the wave overtopping characteristics of artificially roughened seawalls in a suite of laboratory experiments conducted in a two-dimensional wave flume at the University of Warwick, UK. &#160;An impermeable sloping foreshore with a uniform slope of 1 in 20 was constructed in front of a vertical seawall. The seawall was subsequently modified by including 10 no. different test combinations of surface protrusions of varying scale and surface density, replicating &#8216;green&#8217; measures suitable for retrofitting to existing seawalls.&#160; Wave overtopping was measured for each test.&#160; All tests comprised approximately 1000 JONSWAP pseudo-random wave sequences. Both impulsive and non-impulsive wave conditions were considered in experiments with two constant deep-water wave steepness values of 2% and 5%.Results from benchmark (plain seawalls) experiments showed an overall good agreement with predictions from new overtopping manual, EurOtop II, the European empirical design guidance for wave overtopping of sea defences and related structures. &#160;However, test results for the ecologically modified sea defences under impulsive (breaking) wave conditions showed significant reductions (up to factor 4) in overtopping compared to predictions from EurOtop codes. &#160;Reductions in overtopping for artificially roughened defences under non-impulsive wave conditions were less conclusive.&#160; Overall, results indicate that there can be a dual benefit in retrofitting sea defences with ecological features, the first being enhanced biodiversity in the coastal zone and the second being reduced flood risk in coastal areas from reductions in overtopping, particularly for breaking wave conditions.The work in this paper is being undertaken as part of the Interreg funded Ecostructure project (www.ecostructureproject.eu), part-funded by the European Regional Development Fund through the Ireland Wales Cooperation Programme 2014-2020.

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REDUCTION OF WAVE OVERTOPPING RATE BY THE USE OF ARTIFICIAL REEFS

Coastal Engineering Proceedings ◽

10.9753/icce.v21.23 ◽

1988 ◽

Vol 1 (21) ◽

pp. 23

Author(s):

Toru Sawaragi ◽

Ichiro Deguchi ◽

San-Kil Park

Keyword(s):

Wave Breaking ◽

Artificial Reef ◽

Numerical Procedure ◽

Artificial Reefs ◽

Irregular Waves ◽

Analysis Method ◽

Wave Analysis ◽

Wave Overtopping ◽

Unidirectional Flow ◽

Individual Wave

A wave overtopping rate from a sea dike of various toe depths is formulated based on a weir model in an unidirectional flow. To evaluated the wave overtopping rate from a seadike on an artificial reef by the weir model, a numerical procedure for predicting wave transformations including the effect of forced wave breaking on the reef is constructed. After confirming the applicability of the model through experiments with regular and irregular waves, the effect of artificial reef on wave overtopping is discussed. So-called individual wave analysis method is shown to he applicable to the wave overtopping caused by irregular waves.

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Predicting Breaking Wave Conditions Using Gene Expression Programming

Coastal Engineering Journal ◽

10.1142/s0578563417500176 ◽

2017 ◽

Vol 59 (3) ◽

pp. 1750017-1-1750017-14 ◽

Cited By ~ 5

Author(s):

Bryson Robertson ◽

Bahram Gharabaghi ◽

Hannah E. Power

Keyword(s):

Gene Expression ◽

Gene Expression Programming ◽

Breaking Wave ◽

Wave Conditions

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Effectiveness of Chemical Dispersants under Breaking Wave Conditions

The Use of Chemicals in Oil Spill Response ◽

10.1520/stp15398s ◽

2009 ◽

pp. 310-310-31 ◽

Cited By ~ 2

Author(s):

D Mackay

Keyword(s):

Breaking Wave ◽

Wave Conditions

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AN EVALUATION OF SUSPENDED SEDIMENT CONCENTRATION MODELS UNDER BREAKING WAVES

Coastal Engineering Proceedings ◽

10.9753/icce.v36.sediment.42 ◽

2018 ◽

pp. 42

Author(s):

Gabriel Lim ◽

Ravindra Jayaratne ◽

Tomoya Shibayama

Keyword(s):

Kinetic Energy ◽

Suspended Sediment ◽

Suspended Sediment Concentration ◽

Critical Evaluation ◽

Sediment Concentration ◽

Breaking Waves ◽

Breaking Wave ◽

Wave Conditions ◽

Improved Accuracy ◽

Bed Friction

Implementing the effects of turbulent kinetic energy (TKE) is essential in producing accurate suspended sediment concentration (SSC) models, especially under breaking wave conditions. SSC is commonly attributed to two different turbulent sources under breaking wave conditions: 1) bed-friction and 2) breaking-induced turbulent vortices. Numerous studies have endeavoured to quantify the effects of TKE and incorporate them into SSC models. To name a few: Mocke & Smith (1992, henceforth MS92), Shibayama & Rattanapitikon (1993, henceforth SR93), Jayaratne & Shibayama (2007, henceforth JS07), and Yoon et al. (2015, henceforth Y15). The present study evaluates these 4 existing SSC models and validates them against recently published datasets from the â€˜CROSSTEXâ€™ (Yoon & Cox, 2010), â€˜SandT-Proâ€™ (Ribberink et al., 2014) and â€˜SINBADâ€™ (vdZ et al. 2015) projects. Following critical evaluation, suggestions are made to enhance existing SSC models, and these findings are then incorporated into producing two new SSC models that indicate improved accuracy.

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VERTICAL SEA WALL CREST MODIFICATIONS FOR OVERTOPPING

Coastal Engineering Proceedings ◽

10.9753/icce.v36.structures.71 ◽

2018 ◽

pp. 71

Author(s):

Dogan Kisacik ◽

Gulizar Ozyurt Tarakcioglu ◽

Cuneyt Baykal ◽

Gokhan Kaboglu

Keyword(s):

Urban Areas ◽

Vertical Wall ◽

Breaking Wave ◽

Limited Information ◽

Coastal Structures ◽

Wave Overtopping ◽

Wave Basin ◽

First Results ◽

Set Up ◽

Sea Wall

Crest modifications such as a storm wall, parapet or a bullnose are widely used to reduce the wave overtopping over coastal structures where spatial and visual demands restrict the crest heights, especially in urban areas. Although reduction factors of these modifications have been studied for sloped structures in EurOtop Manual (2016), there is limited information regarding the vertical structures. This paper presents the experimental set-up and first results of wave overtopping tests for a vertical wall with several different super structure types: a) seaward storm wall, b) sloping promenade, c) landward storm wall, d) stilling wave basin (SWB), e) seaward storm wall with parapet, f) landward storm wall on the horizontal promenade with parapet, g) landward storm wall with parapet, h) stilling wave basin (SWB) with parapet, under breaking wave conditions. The SWB is made up of a seaward storm wall (may be a double shifted rows) , a sloping promenade (basin) and a landward storm wall. The seaward storm wall is partially permeable to allow the evacuation of the water in the basin.

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