scholarly journals WAVE OVERTOPPING SIMULATOR TESTS IN VIET NAM

2011 ◽  
Vol 1 (32) ◽  
pp. 2
Author(s):  
Hai Trung Le ◽  
Jentsje Van der Meer ◽  
Gerrit Jan Schiereck ◽  
Vu Minh Cat ◽  
Gerben Van der Meer
Keyword(s):  
Erosion Resistance ◽  
Storm Surges ◽  
Bermuda Grass ◽  
Viet Nam ◽  
Vetiver Grass ◽  
Wave Overtopping ◽  
Maximum Discharge ◽  
Sea Dikes

Sea dikes in Viet Nam have been built up during a long history. Every year, about 4 to 6 storms attack the coast and cause severe damages of the sea dikes. Till now, little is known about strength and stability of the inner slope covered with grass under impacts of wave overtopping during storm surges. Destructive tests have been performed with the Wave Overtopping Simulator in Viet Nam revealing that grass slopes are able to withstand a certain amount of wave overtopping. In Hai Phong, a slope section covered by Vetiver grass could suffer a maximum wave overtopping discharge of up to 120 l/s per m. In Nam Dinh, three tested locations within a short dike section of 50 m show a large variation in erosion resistance of the Bermuda grass slope with maximum discharge of 20, 40 and 70 l/s per m.

Guidance on erosion resistance of inner slopes of dikes from three years of testing with the Wave Overtopping Simulator

2010 ◽  
pp. 2: 460-473 ◽  
Author(s):  
Jentsje van der Meer ◽  
Remco Schrijver ◽  
Bianca Hardeman ◽  
André van Hoven ◽  
Henk Verheij ◽  
...  
Keyword(s):  
Erosion Resistance ◽  
Wave Overtopping

scholarly journals Effect of Variations in Water Level and Wave Steepness on the Robustness of Wave Overtopping Estimation

2020 ◽  
Vol 8 (2) ◽  
pp. 63
Author(s):  
Nils B. Kerpen ◽  
Karl-Friedrich Daemrich ◽  
Oliver Lojek ◽  
Torsten Schlurmann
Keyword(s):  
Water Level ◽  
Wave Spectrum ◽  
Water Environment ◽  
Physical Modelling ◽  
Storm Surges ◽  
Water Levels ◽  
Coastal Protection ◽  
Wave Steepness ◽  
Wave Overtopping

The wave overtopping discharge at coastal defense structures is directly linked to the freeboard height. By means of physical modelling, experiments on wave overtopping volumes at sloped coastal structures are customarily determined for constant water levels and static wave steepness conditions (e.g., specific wave spectrum). These experiments are the basis for the formulation of empirically derived and widely acknowledged wave overtopping estimations for practical design purposes. By analysis and laboratory reproduction of typical features from exemplarily regarded real storm surge time series in German coastal waters, the role of non-stationary water level and wave steepness were analyzed and adjusted in experiments. The robustness of wave overtopping estimation formulae (i.e., the capabilities and limitations of such a static projection of dynamic boundary conditions) are outlined. Therefore, the classic static approach is contrasted with data stemming from tests in which both water level and wave steepness were dynamically altered in representative arrangements. The analysis reveals that mean overtopping discharges for simple sloping structures in an almost deep water environment could be robustly estimated for dynamic water level changes by means of the present design formulae. In contrast, the role of dynamic changes of the wave steepness led to a substantial discrepancy of overtopping volumes by a factor of two. This finding opens new discussion on methodology and criteria design of coastal protection infrastructure under dynamic exposure to storm surges and in lieu of alterations stemming from projected sea level rise.

scholarly journals INFLUENCE OF CROWN-WALL ON WAVE OVERTOPPING PROBABILITY AND PROBABILITY DISTRIBUTION OVER A SEAWALL

2018 ◽  
pp. 70
Author(s):  
Jiayue Gu ◽  
Xin Hu ◽  
Shuguang Liu ◽  
Quanhe Ju
Keyword(s):  
Design Method ◽  
Storm Surges ◽  
Wave Overtopping ◽  
Individual Volume ◽  
The Pacific ◽  
Individual Wave ◽  
The Pacific Ocean ◽  
Engineering Measure ◽  
Overtopping Probability ◽  
The Stability

In the past decades, the crest height of the seawall was determined by the allowable average wave overtopping rate q. Franco (1994) concluded that individual wave overtopping，particularly the maximum individual volume, provided a better design method than q, considering the stability of the seawall and the safety of vehicles and people along the coastal area protected by the coastal defense structures. Shanghai, located on the west bank of the Pacific Ocean, is quite sensitive to the risk of storm surges and violent wave overtopping. The crown-wall serves as an engineering measure to reduce the wave overtopping effectively.

scholarly journals ON THE EFFECT OF ARMOUR BLOCK FACING ON THE QUANTITY OF WATTE OVERTOPPING

1968 ◽  
Vol 1 (11) ◽  
pp. 55
Author(s):  
Naofumi Shiraishi ◽  
Atusushi Numata ◽  
Taiji Endo
Keyword(s):  
Wave Energy ◽  
Field Observation ◽  
Storm Surges ◽  
Design Criterion ◽  
Characteristic Functions ◽  
Crown Height ◽  
Wave Overtopping

Japan, surrounded by sea, is constantly threatened by storm surges and beach erosions, for which protection works are being vigorously undertaken. As a measure for protection, facings of various armour blocks have come to be used for the seawalls and embankments. This is a skillful utilization of characteristic functions of armour blocks to dissipate and absorb wave energy effectively. However, systematic experiments and studies on this subject have been conducted only in very few cases. This paper treats of the effect of the facing of armour blocks on wave overtopping by comparison of the quantity of waves topped over the vertical seawal] with facing and that of without facing. Furthermore, this paper attempts to compare the results of the field observation and the experiments on the quantity of wave overtopping. Based on these data, the authors present a design criterion of the crown height of seawall with armour block facing.

scholarly journals ROUGHNESS FACTOR FOR MULTI-LAYER ARMOUR AS OVERTOPPING ESTIMATOR

2020 ◽  
pp. 25
Author(s):  
Leopoldo Franco ◽  
Yuri Pepi ◽  
Stefano de Finis ◽  
Verdiana Iorio ◽  
Giorgio Bellotti ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
Storm Surges ◽  
Random Wave ◽  
Roughness Factor ◽  
Coastal Structures ◽  
Wave Overtopping ◽  
Wave Flume ◽  
Physical Model Tests ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

Nowadays one of the most challenging problem for engineers is to adapt existing coastal structures to climate changes. Wave overtopping is highly sensitive to the increasing extreme water depths due to higher storm surges coupled with sea level rise. One way to face these problems for rubble mound breakwaters is to add one or more layers to the existing armour. Prediction of wave overtopping of coastal structures is presently obtained from empirical formulae in EurOtop (2018). For the case of overtopping over multi-layer armour, no validated method exists, so prediction must be based upon assumptions and judgement, with related uncertainties. This study is focused on the effects of different types of armour, the number of layer and other structural characteristics on the roughness factor f. The main effects of porosity and roughness will be investigated. This paper analyzes the results of several new physical model tests of different rubble mound breakwaters reproduced at the new medium scale random wave flume of the Department of Engineering of Roma Tre University.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/8cOdqkqQ-9s

scholarly journals EFFECTS OF WAVE LOAD ON THE LONG-TERM VEGETATION DEVELOPMENT AND THEIR RESISTANCE AS GRASS REVETMENTS ON SEA DIKES

2018 ◽  
pp. 87
Author(s):  
Jochen Michalzik ◽  
Sven Liebisch ◽  
Torsten Schlurmann
Keyword(s):  
Ecosystem Services ◽  
Storm Surges ◽  
Coastal Protection ◽  
Wave Load ◽  
Vegetation Development ◽  
Safety Standards ◽  
Wave Basin ◽  
Proper Design ◽  
Sea Dikes

Construction and design processes of revetments, sea dikes and estuarine dikes along the German coastline adhere the paradigm to protect and safeguard reliably the coastal hinterland from wave attack and storm surges. Following these standards coastal protection structures provide only poor ecosystem services in any proper design or maintenance approach. As a result, the EcoDike-project has been started with the aim to quantify and enhance the ecosystem services of revetments, sea dikes and estuarine dikes while preserving or possibly even enhancing the existing safety standards. Therefore, a profound understanding of the complex long-term interactions between wave load and vegetation development on sea dikes is inevitable. To achieve these objectives a typical seadike in prototype scale is tested under realistic and long-term wave loading in the new outdoor wave basin at the Ludwig-Franzius-Institute in Hannover (Germany).

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.

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.

Wave overtopping and splash-up at seawalls with bullnose

2020 ◽  
Vol 20 (3) ◽  
pp. 333-342
Author(s):  
Le Hai Trung ◽  
Dang Thi Linh ◽  
Tang Xuan Tho ◽  
Nguyen Truong Duy ◽  
Tran Thanh Tung
Keyword(s):  
Storm Surges ◽  
Model Tests ◽  
Scale Model ◽  
Small Scale ◽  
Wave Overtopping ◽  
Run Up ◽  
Coast Of Vietnam ◽  
Small Scale Model ◽  
Wall Interactions

Seawalls have been erected to protect hundreds of towns and tourism areas stretching along the coast of Vietnam. During storm surges or high tides, wave overtopping and splash-up would often threaten the safety of infrastructures, traffic and residents on the narrow land behind. Therefore, this study investigates these wave-wall interactions via hydraulic small scale model tests at Thuyloi University. Remarkably, the structure models were shaped to have different seaward faces and bullnoses. The wave overtopping discharge and splash run-up height at seawalls with bullnose are significantly smaller than those without bullnose. Furthermore, the magnitude of these decreasing effects is quantitatively estimated.

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
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