scholarly journals Wave Overtopping Discharge for Very Gently Sloping Foreshores

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1695
Author(s):  
Thu-Ha Nguyen ◽  
Bas Hofland ◽  
Vu Dan Chinh ◽  
Marcel Stive
Keyword(s):  
Wave Period ◽  
Wave Overtopping ◽  
Slope Method ◽  
Near Shore ◽  
Crucial Parameter ◽  
Sea Dikes

The spectral wave period T m − 1 , 0 at the toe of sea-dikes is a crucial parameter to predict wave overtopping discharge over sea-dikes. It is known from literature that this period quickly increases when waves reach shallow foreshores; however, sometimes the assumption is made that the wave period remains constant from offshore to near-shore, leading to an underestimation of the near-shore wave period. Several formulae have been proposed to resolve the underestimation of wave overtopping discharges for very shallow foreshores. These corrective formulations confirm the tendency of underestimating the overtopping discharges over a very gently sloping foreshore but are not validated for foreshore slopes gentler than 1:500. The “equivalent slope” method based on a recent study is inappropriate for these very gently sloping foreshores due to the breaker parameter being much smaller than seven. This study proposes an extension of the correction and finds that spectral wave periods can reach values two times those offshore.

scholarly journals LABORATORY EXPERIMENTS OF WAVE OVERTOPPING OF REVETMENT STRUCTURES IN REEF ENVIRONMENTS

2018 ◽  
pp. 80
Author(s):  
Kristen Splinter ◽  
Liqun Li ◽  
Matt Blacka
Keyword(s):  
Wave Breaking ◽  
Coastal Region ◽  
Water Levels ◽  
Full Spectrum ◽  
Reef Environment ◽  
Wave Overtopping ◽  
Reef Environments ◽  
Natural Protection ◽  
Shallow Lagoon ◽  
Sea Dikes

Reefs offer natural protection to many coastal island nations through the physical processes of wave breaking on the reef rim and thus, reducing the wave energy that reaches the shoreline. However, both mean and infragravity water levels build up over the reef due to wave breaking on the reef top that can lead to coastal inundation and serious damage (Gourlay 1996a; Gourlay 1996b; Blacka et al. 2015). To protect the community around the coastal region, the construction of defensive structures, such as revetments or sea dikes may be required. The present study is focused on wave overtopping discharge on smooth revetments within the reef environment, which is not fully understood. Classical formulas that estimate overtopping of revetments (see Van der Meer et al. 2016 and references therein) are based on waves breaking in deep to shallow water either in front of the structure or directly on the structure. Recently, Altomare (2016) updated Van Gent’s (1999) formula of overtopping discharge of smooth sea dikes on shallow foreshores to include very shallow foreshores. The updated equation estimates dimensionless over-topping as a function of the full spectrum wave properties at the toe of the structure and an equivalent slope term. As the reef environment can often be described as a very flat and shallow lagoon seaward of the shoreline, the Altomare formula can potentially be adopted to predict the overtopping discharge on smooth revetments in reef environments, but this has yet to be tested.

Wave overtopping of sea dikes with very shallow foreshores

2016 ◽  
Vol 116 ◽  
pp. 236-257 ◽  
Author(s):  
C. Altomare ◽  
T. Suzuki ◽  
X. Chen ◽  
T. Verwaest ◽  
A. Kortenhaus
Keyword(s):  
Wave Overtopping ◽  
Sea Dikes

scholarly journals WAVE OVERTOPPING AT BERM BREAKWATERS IN LINE WITH EUROTOP

2012 ◽  
Vol 1 (33) ◽  
pp. 12 ◽  
Author(s):  
Sigurdur Sigurdarson ◽  
Jentsje W. Van der Meer
Keyword(s):  
Hydraulic Model ◽  
Model Tests ◽  
Wave Period ◽  
Wave Steepness ◽  
Wave Overtopping ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

The paper presents the development of a new overtopping formula for berm breakwaters. Overtopping data from hydraulic model tests of berm breakwaters have been gathered and reanalysed in line with the procedure in the EurOtop Manual. The data shows a clear dependency on wave period or wave steepness, which is in contrast to the main conclusion of the CLASH project and the EurOtop Manual for conventional rubble mound breakwaters. The formula is roughly validated on prototype performance.

A MODEL SYSTEM FOR BREACHING OF SEA DIKES INITIATED BY WAVE OVERTOPPING

2009 ◽  
Author(s):  
Claudia D'Eliso ◽  
Hocine Oumeraci ◽  
Andreas Kortenhaus
Keyword(s):  
Model System ◽  
Wave Overtopping ◽  
Sea Dikes

scholarly journals Overtopping Metrics and Coastal Safety: A Case of Study from the Catalan Coast

2020 ◽  
Author(s):  
Corrado Altomare ◽  
Xavi Gironella ◽  
Tomohiro Suzuki ◽  
Giacomo Viccione ◽  
Alessandra Saponieri
Keyword(s):  
Flow Characteristics ◽  
Flow Depth ◽  
Detailed Characterization ◽  
Wave Overtopping ◽  
Experimental Campaign ◽  
Catalan Coast ◽  
The Relationship ◽  
Hazard Levels ◽  
Sea Dikes

Design criteria for coastal defenses exposed to wave overtopping are usually assessed by mean overtopping discharges and maximum individual overtopping volumes. However, it is often difficult to give clear and precise limits of tolerable overtopping for all kind of layouts. A few studies analyzed the relationship between wave overtopping flows and hazard levels for people on sea dikes, confirming that one single value of admissible mean discharge or individual overtopping volume is not a sufficient indicator of the hazard, but detailed characterization of flow velocities and depths is required. This work presents the results of an experimental campaign aiming at characterizing the flow characteristics associated to maximum individual overtopping volumes for an urbanized stretch of a town along the Catalan coast, where a walking and bike path and a railway run along the coastline are exposed to significant overtopping events every stormy season. The work compares different safety criteria for pedestrian. Results prove that safety of pedestrian on a sea dike can be still guaranteed even for overtopping volumes larger than 1000 l/m. Pedestrian hazard is rather proved to be linked to the combination of overtopping flow velocity and flow depth.

scholarly journals COMPARISONS OF WAVE OVERTOPPING DISCHARGES AND DAMAGES OF THE NTOU VERTICAL SEAWALL DUE TO TWO SIMILAR SUPER TYPHOONS ON KEELUNG COAST OF TAIWAN

2011 ◽  
Vol 1 (32) ◽  
pp. 3 ◽  
Author(s):  
Da-Wei Chen ◽  
Shiaw-Yih Tzang ◽  
Shan-Hwei Ou
Keyword(s):  
Water Depth ◽  
Wave Period ◽  
Wave Overtopping ◽  
Swan Model ◽  
Effective Reduction ◽  
Failure Event ◽  
Average Wave ◽  
Wave Conditions ◽  
Typhoon Herb

In this study, SWAN model was first applied to obtain wave conditions during Typhoon Herb (1996) and Krosa (2007). Then the results were used for estimating the wave overtopping discharge with existing empirical formulae selected from EurOtop manual. In the EurOtop formulae, calculations of overtopping discharges can be improved by adapting average wave period (Tm-1,0) for swell conditions. The results show that the peak overtopping discharges during Typhoon Herb (1996) are larger than those during Typhoon Krosa (2007) at the two selected sites. In addition, the water depth at toe of eastern NTOU seawalls (NTOU 2) are shallower than that at northern NTOU seawall (NTOU 1) so that the discharges at NTOU 1 are larger than those at NTOU 2. The calculations show that the peak wave overtopping discharges during both typhoons are greater than the criteria for damages on back slope of seawalls, which agrees with the NTOU seawall failure event during Typhoon Herb. The predicted failure does not again happen to NTOU seawall during Typhoon Krosa implying the effective reduction in overtopping discharges by lifting up 1m of the crest after rebuilding the previously damaged seawall.

scholarly journals Wave Overtopping Simulator Tests on Vietnamese Sea Dikes

2014 ◽  
Vol 56 (3) ◽  
pp. 1450017-1-1450017-21 ◽  
Author(s):  
Trung Le Hai ◽  
Jentsje van der Meer ◽  
Henk Jan Verhagen
Keyword(s):  
Wave Overtopping ◽  
Sea Dikes
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