scholarly journals IMPLICATIONS OF CORAL REEF MINING PITS ON 2D HYDRODYNAMICS

2020 ◽  
pp. 28
Author(s):  
Sebastiaan Klaver ◽  
Kees Nederhoff ◽  
Alessio Giardino
Keyword(s):  
Wave Energy ◽  
Reef Flat ◽  
Wave Interaction ◽  
Storm Surges ◽  
Small Island ◽  
Coastal Protection ◽  
Wave Runup ◽  
Protection Measures ◽  
Circulation Patterns ◽  
The Impact

Small Island Developing States (SIDS) are among the most vulnerable areas to the impact of natural hazards and climate change. Flooding due to storm surges and extreme waves, coastal erosion, and salinization of freshwater lenses are already a serious threat and could lead to irreversible consequences in the coming decades. On the other hand, reef flat mining is one of the most common practices to source the required material for the implementation of coastal protection measures on SIDS. There are strong concerns about this practice, because partial removal of the protective reef could increase wave impacts on the islands. However, the available data and knowledge on the effects of these mining pits are currently very limited. Klaver et al. (2019) studied the effects that pits may have on nearshore hydrodynamics and wave runup. Results obtained via numerical modeling indicate that excavation pits cause a decrease in infragravity wave energy around the fundamental mode of the reef, which is partly caused by reduced wave transmission. Similarly, changes in sea and swell (SS) wave energy are attributed to reduced transmission, as well as a decrease in wave dissipation and (triad) wave-wave interaction. Earlier studies by Ford et al. (2013) and Yao et al. (2016) point out that mining pits may lead to additional two-dimensional effects. In this presentation, we present the potential 2D effects of reef flat excavation pits on nearshore hydrodynamics. More specifically, we aim to assess the impact of excavation pits on nearshore circulation patterns, which could be an indicator of coastal morphological changes.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/85-IMM66eWE

scholarly journals The Performance of a Spectral Wave Model at Predicting Wave Farm Impacts

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5728
Author(s):  
J. Cameron McNatt ◽  
Aaron Porter ◽  
Christopher Chartrand ◽  
Jesse Roberts
Keyword(s):  
Wave Field ◽  
Wave Energy ◽  
Wave Interaction ◽  
Wave Model ◽  
Skill Score ◽  
Coastal Protection ◽  
Linear Wave ◽  
Ocean Wave Energy ◽  
Wave Farm ◽  
The Impact

For renewable ocean wave energy to support global energy demands, wave energy converters (WECs) will likely be deployed in large numbers (farms), which will necessarily change the nearshore environment. Wave farm induced changes can be both helpful (e.g., beneficial habitat and coastal protection) and potentially harmful (e.g., degraded habitat, recreational, and commercial use) to existing users of the coastal environment. It is essential to estimate this impact through modeling prior to the development of a farm, and to that end, many researchers have used spectral wave models, such as Simulating WAves Nearshore (SWAN), to assess wave farm impacts. However, the validity of the approaches used within SWAN have not been thoroughly verified or validated. Herein, a version of SWAN, called Sandia National Laboratories (SNL)-SWAN, which has a specialized WEC implementation, is verified by comparing its wave field outputs to those of linear wave interaction theory (LWIT), where LWIT is theoretically more appropriate for modeling wave-body interactions and wave field effects. The focus is on medium-sized arrays of 27 WECs, wave periods, and directional spreading representative of likely conditions, as well as the impact on the nearshore. A quantitative metric, the Mean Squared Skill Score, is used. Results show that the performance of SNL-SWAN as compared to LWIT is “Good” to “Excellent”.

scholarly journals Evolution of the northern Fujian coast under the impact of natural and anthropogenic forces, 1976–2017: an analysis of coastal monitoring and satellite images

2019 ◽  
Vol 2 (1) ◽  
pp. 72-86 ◽  
Author(s):  
Shuai Cong ◽  
Xiao Wu ◽  
Yong Zhang ◽  
Biying Xue ◽  
Houjie Wang
Keyword(s):  
Storm Surges ◽  
High Water ◽  
Scientific Basis ◽  
Extreme Weather Events ◽  
Coastal Protection ◽  
Coastal Monitoring ◽  
Practical Applications ◽  
Coastal Profile ◽  
The Impact ◽  
Sand Extraction

The province of Fujian on China’s southeast coast is severely impacted by typhoons. Based on coastal profile monitoring and 40 years of satellite data, this paper analyzed the response of coastal profiles to natural and anthropogenic forces along the northern part of Fujian’s coast. Results indicated that the pattern of coastal evolution differed largely on cross-shore profiles and longshore coastlines. Only a few sandy coasts were severely affected by extreme weather events in summer, such as typhoons and storm surges, which may result from the wind direction relative to the coast. The cross-shore profiles changed drastically while the mean high-water coastline remained stable. In contrast, anthropogenic forces had a dual effect due to artificial sand extraction and reclamation. Artificial sand extraction usually occurred on sandy coasts, resulting in a decrease in some local surface profiles of tens of centimeters to metres in two years. Reclamation had the main impact on muddy coasts, especially in bays, causing seaward progradation during the past 40 years. The impacts of human activities on muddy coasts were far greater than natural factors. Findings from our coastal monitoring study for both sandy and muddy coasts provide an important scientific basis for practical applications, such as Fujian coastal protection, coastal zone exploitation, and utilization planning.

scholarly journals Long-Term Assessment of an Innovative Mangrove Rehabilitation Project: Case Study on Carey Island, Malaysia

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Shervin Motamedi ◽  
Roslan Hashim ◽  
Rozainah Zakaria ◽  
Ki-Il Song ◽  
Bakrin Sofawi
Keyword(s):  
Wave Energy ◽  
Ph Value ◽  
Storm Surges ◽  
Coastal Protection ◽  
Coastal Structures ◽  
Mangrove Seedlings ◽  
Salinity Index ◽  
Mangrove Rehabilitation

Wave energy and storm surges threaten coastal ecology and nearshore infrastructures. Although coastal structures are conventionally constructed to dampen the wave energy, they introduce tremendous damage to the ecology of the coast. To minimize environmental impact, ecofriendly coastal protection schemes should be introduced. In this paper, we discuss an example of an innovative mangrove rehabilitation attempt to restore the endangered mangroves on Carey Island, Malaysia. A submerged detached breakwater system was constructed to dampen the energy of wave and trap the sediments behind the structure. Further, a large number of mangrove seedlings were planted using different techniques. Further, we assess the possibility of success for a future mangrove rehabilitation project at the site in the context of sedimentology, bathymetry, and hydrogeochemistry. The assessment showed an increase in the amount of silt and clay, and the seabed was noticeably elevated. The nutrient concentration, the pH value, and the salinity index demonstrate that the site is conducive in establishing mangrove seedlings. As a result, we conclude that the site is now ready for attempts to rehabilitate the lost mangrove forest.

scholarly journals DEVELOPMENT OF COASTAL PROTECTION MEASURES FOR SMALL ISLANDS IN THE WADDEN SEA USING A RISK-BASED APPROACH

2012 ◽  
Vol 1 (33) ◽  
pp. 48 ◽  
Author(s):  
Theide Wöffler ◽  
Holger Schüttrumpf ◽  
Arne Arns ◽  
Hilmar Von Eynatten ◽  
Roger Häußling ◽  
...  
Keyword(s):  
Wadden Sea ◽  
Expert Knowledge ◽  
Management Strategies ◽  
Storm Surges ◽  
Sensitivity Analyses ◽  
Coastal Protection ◽  
Protection Measures ◽  
Engineering Research ◽  
Wave Heights ◽  
The Difference

The Halligen in the Northfrisian part of the UNESCO – World Natural Heritage Wadden Sea are exposed to extreme storm surges due to climate change and sea level rise. Existing coastal protection measures in this area do not consider the future sea state and are mainly based on tradition and expert knowledge. The presented work is part of the project ZukunftHallig (supported by the German Coastal Engineering Research Council) and has the main objective to design and evaluate new coastal protection techniques and management strategies for the Halligen. With numerical simulations hydrological parameters are investigated. Furthermore sensitivity analyses expose possible variations in future storm surges and illustrate the difference in significant wave heights for varying wind climates. This risk based approach of the project is a suitable way to ensure life for future generations on these islands under sustainable ecological und economic conditions.

scholarly journals Impact of coastal forcing and groundwater recharge on the growth of fresh groundwater resources in a mega-scale beach nourishment

2017 ◽  
Author(s):  
Sebastian Huizer ◽  
Max Radermacher ◽  
Sierd de Vries ◽  
Gualbert H. P. Oude Essink ◽  
Marc F. P. Bierkens
Keyword(s):  
Groundwater Recharge ◽  
Land Surface ◽  
Morphological Changes ◽  
Groundwater Resources ◽  
Beach Nourishment ◽  
Coastal Protection ◽  
Tidal Dynamics ◽  
Fresh Groundwater ◽  
Protection Measures ◽  
The Impact

Abstract. Large concentrated sand replenishments or nourishments are one of the few coastal protection measures that can simultaneously result in an increase of local fresh groundwater resources. For a large beach nourishment called the Sand Engine – constructed in 2011 at the Dutch coast – we have examined the impact of groundwater recharge and coastal forcing (i.e. natural processes that drive coastal hydro- and morphodynamics) on the growth of the fresh groundwater resources between 2011 and 2016. Measurements of the morphological change and the tidal dynamics were incorporated in a calibrated three-dimensional and variable-density groundwater model of the study area. Simulations with this model showed that the detailed incorporation of the local hydro- and morphodynamics and the actual recharge rate can result in a reliable reconstruction of the growth in fresh groundwater resources. Similarly, the neglect of tidal dynamics, land-surface inundations and morphological changes in model simulations can result in considerable overestimations of the volume of fresh groundwater. In particular wave run-up and coinciding coastal erosion during storm surges limit the growth in fresh groundwater resources in dynamic coastal environments, and should be considered at potential nourishment sites to delineate the area that is vulnerable to salinization.

scholarly journals Microfauna- and sedimentology-based facies analysis for palaeolandscape reconstruction in the back-barrier area of Norderney (NW Germany)

2021 ◽  
Vol 100 ◽  
Author(s):  
Annastasia Elschner ◽  
Juliane Scheder ◽  
Friederike Bungenstock ◽  
Alexander Bartholomä ◽  
Thorsten M Becker ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Tidal Flat ◽  
Sediment Cores ◽  
Depositional Environments ◽  
Coastal Protection ◽  
Protection Measures ◽  
Radiocarbon Dates ◽  
Minimum Age ◽  
Coastal Changes ◽  
The Impact

Abstract Palaeolandscape reconstructions at the German North Sea coast are essential for the understanding of coastal changes and dynamic landscape-forming processes. This study contributes to reconstructing Holocene coastal changes in the back-barrier area of the East Frisian island of Norderney and draws conclusions on the local palaeogeography. Five sediment cores were analysed in terms of sedimentology (grain-size distribution), geochemistry (TOC, TIC, N, C/N), microfauna (foraminifers and ostracods) and 13 radiocarbon dates. In order to identify driving environmental factors and support the facies interpretation, multivariate statistics (PCA) were carried out. Additional cores from the surrounding area (WASA Project and ‘Landesamt für Bergbau, Energie und Geologie’ (LBEG) Hannover) enabled correlation of the investigated cores over a transect of ~6 km, showing six depositional environments, which can be used for landscape reconstruction. Deposition starts with periglacial (aeolian and glaciofluvial) Pleistocene sediments, with subsequent pedogenesis followed by swamp conditions that develop into a salt marsh. The overlying tidal-flat sediments are partially cut by (fossil and recent) channel deposits. A hiatus at the base of the tidal-flat deposits that spans some 3000 years hints at their reworking caused by a combination of antrophogenic coastal protection measures and the impact of storms. Furthermore, based on the profile correlation and the age data, a widespread salt-marsh area with a minimum age of ~4000 cal BP is defined for the ‘Hohes Riff’ in the southwestern back-barrier of Norderney Island.

scholarly journals The Effect of a Wave Energy Farm Protecting an Aquaculture Installation

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2109 ◽  
Author(s):  
Dina Silva ◽  
Eugen Rusu ◽  
C. Guedes Soares
Keyword(s):  
Wave Energy ◽  
Positive Impact ◽  
Wave Climate ◽  
Coastal Protection ◽  
Wave Energy Converters ◽  
The North ◽  
Wave Conditions ◽  
Offshore Aquaculture ◽  
Wave Farm ◽  
The Impact

This paper assesses the impact of a farm of wave energy converters on a nearby offshore aquaculture installation and on the nearshore dynamics. The coastal area targeted is Aguçadoura, located in the north of Portugal, where the world’s first wave farm operated in 2008. The study is focused mainly on the evaluation of the sheltering effect provided by the wave farm to the aquaculture cages. Furthermore, the possible impact on the coastal wave climate of such an energy park is also evaluated. These objectives are accomplished by performing simulations, corresponding to the wave conditions, which are more often encountered in that coastal environment. The SWAN model (Simulating WAves Nearshore) was adopted for this. Various transmission scenarios are considered to account for the impact of different types of wave converter farms on the downwave conditions. The results show that such a wave energy park might have a clear positive impact on the wave conditions fish farm installed downwave and it might also have a beneficial influence on shoreline dynamics from the perspective of coastal protection.

scholarly journals Impact of coastal forcing and groundwater recharge on the growth of a fresh groundwater lens in a mega-scale beach nourishment

2018 ◽  
Vol 22 (2) ◽  
pp. 1065-1080 ◽  
Author(s):  
Sebastian Huizer ◽  
Max Radermacher ◽  
Sierd de Vries ◽  
Gualbert H. P. Oude Essink ◽  
Marc F. P. Bierkens
Keyword(s):  
Groundwater Recharge ◽  
Land Surface ◽  
Morphological Changes ◽  
Groundwater Resources ◽  
Storm Surges ◽  
Beach Nourishment ◽  
Wave Runup ◽  
Tidal Dynamics ◽  
Fresh Groundwater ◽  
The Impact

Abstract. For a large beach nourishment called the Sand Engine – constructed in 2011 at the Dutch coast – we have examined the impact of coastal forcing (i.e. natural processes that drive coastal hydro- and morphodynamics) and groundwater recharge on the growth of a fresh groundwater lens between 2011 and 2016. Measurements of the morphological change and the tidal dynamics at the study site were incorporated in a calibrated three-dimensional and variable-density groundwater model of the study area. Simulations with this model showed that the detailed incorporation of both the local hydro- and morphodynamics and the actual recharge rate can result in a reliable reconstruction of the growth in fresh groundwater resources. In contrast, the neglect of tidal dynamics, land-surface inundations, and morphological changes in model simulations can result in considerable overestimations of the volume of fresh groundwater. In particular, wave runup and coinciding coastal erosion during storm surges limit the growth in fresh groundwater resources in dynamic coastal environments, and should be considered at potential nourishment sites to delineate the area that is vulnerable to salinization.

Numerical investigation of wave interactions in an experimental wave-energy converter using OpenFOAM

2020 ◽  
pp. 095765092096224
Author(s):  
Ali Sangtarash ◽  
Ehsan Roohi
Keyword(s):  
Boundary Conditions ◽  
Wave Energy ◽  
Wave Interaction ◽  
Wave Generation ◽  
Wave Energy Converter ◽  
Wave Flow ◽  
Vertical Force ◽  
Energy Converter ◽  
First Case ◽  
The Impact

In this paper, OpenFOAM wave generation and active wave absorption boundary conditions were used to simulate wave interaction of a specific experimental wave energy converter (WEC) with equilibrium buoys and two power take-off systems that work in parallel, over a broad range of wave conditions. Two solitary and cnoidal wave generation boundary conditions for three different wave heights were implemented at the inlet to generate waves. The validation phase included a comparison of free-surface with numerical results of solitary and cnoidal waves generation at the flume. To investigate the impact of equilibrium buoys, wave flow around the wave energy converter was simulated for two cases. In the first case, WEC was considered as a single box, and in the second, two equilibrium buoys were added to the WEC. By comparison of these two cases, we discovered that although equilibrium buoys decrease the horizontal force on the main box, they cause the production of two efficient vertical forces. One of these forces moves the front equilibrium buoy generating electricity individually from the main box mechanism, and the other vertical force is applied to the back equilibrium buoy accelerating the rotation of the main box. Overall, wave energy absorption is enhanced by using the equilibrium buoys.

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