scholarly journals Geological Evidence of Shoreline Erosion and Mitigation Challenges

2020 ◽  
Vol 1 (2) ◽  
pp. 7-13
Author(s):  
Anthony Woode ◽  
David Kwame Amoah
Keyword(s):  
Sand Dunes ◽  
Mitigation Measures ◽  
Coastal Protection ◽  
Sea Waves ◽  
Protection Measures ◽  
Geological Evidence ◽  
Waves And Currents ◽  
Coastal Cliffs ◽  
Coastal Landform ◽  
Coastal Land

A survey was carried out along parts of the coastal stretch of Accra, the capital of Ghana, to determine the existence andthe extent of erosion. The survey was also to determine the effectiveness of the engineering solutions that have been put inplace. Coastal land forms as evidence of erosion were identified during the field survey. These include landslides of steepcoastal cliffs, coastal caves and arches, retreat of coastal cliffs, headlands, stacks and sand dunes. These pieces of evidenceconfirm earlier findings that the coastal shoreline of Accra is being eroded. The extent of erosion, however, is high in soft rocks and low in hard rocks. Several coastal protection measures have been put in place to address the effects of erosion by the sea waves and currents. These include revetments, jetties, ripraps and beach nourishment. Some of the mitigation measures however have shown signs of failure. The signs include rusted metal basket supporting cobbles of gabions, jetties causing down-current erosion of shoreline cliffs, and reduction in coconut population along the shoreline owing to human activities, such as sand winning and diseases attacks. Sand winning along the shore is lowering shoreline morphology and enhancing sea transgression and the destruction of coastal structures. Keywords: Erosion; Coastal landform; Coastal protection; Revetments; Shoreline morphology

scholarly journals Micro Sand Engine Beach Stabilization Strategy at Puerto Morelos, Mexico

2020 ◽  
Vol 8 (4) ◽  
pp. 247 ◽  
Author(s):  
Mireille Escudero ◽  
Edgar Mendoza ◽  
Rodolfo Silva
Keyword(s):  
Small Scale ◽  
Coastal Protection ◽  
Protection Measure ◽  
Morphological Response ◽  
Protection Measures ◽  
Small Bell ◽  
Waves And Currents ◽  
Maintenance Work ◽  
Negative Impacts ◽  
The Waves

In the last decade, innovative beach nourishment strategies have been developed, driven by the increased worldwide interest in environmentally friendly coastal protection measures. In this context, the massive nourishment project of the Netherlands, known as Sand Engine, begun in 2011, has been hailed as a successful means of beach protection. Continuous monitoring, field campaigns, and numerical modeling have shown that the great volume of sand deployed is gradually transported by the waves and currents along the coastline, avoiding the need for repeated invasive, small scale beach replenishments. A very small, bell-shaped Sand Engine was designed to protect the beachfront at a tourist resort near Puerto Morelos, Mexico. To estimate the morphological response of the beach and the functioning of the micro Sand Engine as a sand reservoir, XBeach numerical modelling was applied to the project. The micro Sand Engine is seen to be a sustainable and eco-friendly coastal protection measure, especially applicable when a large nourishment project is not viable. Maintenance work for the nourishment is cost and time effective, and any negative impacts to sensitive ecosystems nearby can be detected and controlled quickly.

scholarly journals THE JAVA TSUNAMI MODEL: USING HIGHLY-RESOLVED DATA TO MODEL THE PAST EVENT AND TO ESTIMATE THE FUTURE HAZARD

2011 ◽  
Vol 1 (32) ◽  
pp. 25 ◽  
Author(s):  
Widjo Kongko ◽  
Torsten Schlurmann
Keyword(s):  
Sand Dunes ◽  
Accretionary Prism ◽  
Mitigation Measures ◽  
Coastal Protection ◽  
Observation Data ◽  
Maximum Magnitude ◽  
Inundation Area ◽  
Extensive Field ◽  
Run Up ◽  
Tsunami Model

This study is to validate the tsunami model with extensive field observation data gathered from the 2006 Java tsunami. In the relevant study area, where highly-resolved geometric data were recently made available and other related post-tsunami field data have been collected, the tsunami maximum run-up onto land and its marigram have been simulated and evaluated. Several plausible tsunami sources are proposed to adequately mimic the 2006 Java tsunami by including the influence of low rigidity material in the accretionary prism as well as its single-multi fault source type’s effect. Since it has a significant role on tsunami excitation, this parameter and other assumptions are then employed to study an estimated set of reasonable maximum magnitude earthquake-tsunami scenario and projected inundation areas for probable future tsunami on the South Java coastline. In a final step tentative technical mitigation measures are proposed and assessed to deal with adequate coastal protection issues by means of soft (greenbelt, etc.) and hard engineering (sand dunes, etc.) approaches. Their effectiveness in terms of reducing inundation area is assessed and general recommendations for coastal planning authorities are dealt with.

scholarly journals Development of Flood Defense Alternaives for the Beach of Deir El Balah Camp, Palestine

2021 ◽  
Vol 8 (2) ◽  
Keyword(s):  
Coastal Zone ◽  
Selection Process ◽  
Shoreline Change ◽  
Coastal Protection ◽  
Sea Waves ◽  
Protection Measures ◽  
Marine Habitats ◽  
Unconsolidated Sand ◽  
Khan Younis ◽  
Key Dimensions

The development along the coastal zone has led to the host of problems such as erosion, siltation, flooding, loss of coastal resources and the destruction of the fragile marine habitats. The erosion threatens the coastal zone, which affects people's economic, tourist, and recreational life. The main reason of the erosion is due to Khan Younis breakwater and the sea waves working on empty the beachy sand, thereby flooding and scouring the area as it ebbs and removing part of the unconsolidated sand. This study uses Geographic Information System to detect changes in the coastline along Deir El Balah coast during the 1972–2020 period. Shoreline change rates in the form of erosion and accretion patterns are quantified. In addition, four alternatives are proposed to to mitigate the current problems raised by repeated flooding and erosion through reefballs, cubes, geotubes and seawalls and analyze their impacts on coastal protection to provide the best possible mitigations in environmental, economical and engineering terms. Multi criteria analysis is used to assess the alternatives with respect to criteria that capture the key dimensions of the selection process. Multi criteria have been selected and addressed the most important factors when planning, designing, financing, and implementing coastal protection measures. Based on the analysis, the best alternative of three-row reefballs submerged breakwaters is recommended.

scholarly journals A Conflict between Traditional Flood Measures and Maintaining River Ecosystems? A Case Study Based upon the River Lærdal, Norway

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1884
Author(s):  
Ana Juárez ◽  
Knut Alfredsen ◽  
Morten Stickler ◽  
Ana Adeva-Bustos ◽  
Rodrigo Suárez ◽  
...  
Keyword(s):  
Remote Sensing Data ◽  
Freshwater Ecosystems ◽  
River Channel ◽  
Flood Mitigation ◽  
Mitigation Measures ◽  
Flood Events ◽  
Protection Measures ◽  
River Ecosystems ◽  
Hydraulic Models

Floods are among the most damaging of natural disasters, and flood events are expected to increase in magnitude and frequency with the effects of climate change and changes in land use. As a consequence, much focus has been placed on the engineering of structural flood mitigation measures in rivers. Traditional flood protection measures, such as levees and dredging of the river channel, threaten floodplains and river ecosystems, but during the last decade, sustainable reconciliation of freshwater ecosystems has increased. However, we still find many areas where these traditional measures are proposed, and it is challenging to find tools for evaluation of different measures and quantification of the possible impacts. In this paper, we focus on the river Lærdal in Norway to (i) present the dilemma between traditional flood measures and maintaining river ecosystems and (ii) quantify the efficiency and impact of different solutions based on 2D hydraulic models, remote sensing data, economics, and landscape metrics. Our results show that flood measures may be in serious conflict with environmental protection and legislation to preserve biodiversity and key nature types.

scholarly journals The role of the reef–dune system in coastal protection in Puerto Morelos (Mexico)

2018 ◽  
Vol 18 (4) ◽  
pp. 1247-1260 ◽  
Author(s):  
Gemma L. Franklin ◽  
Alec Torres-Freyermuth ◽  
Gabriela Medellin ◽  
María Eugenia Allende-Arandia ◽  
Christian M. Appendini
Keyword(s):  
Sand Dunes ◽  
Coastal Flooding ◽  
Water Levels ◽  
Coastal Protection ◽  
Dune System ◽  
Fore Reef ◽  
Extreme Water Levels ◽  
Reef Environments ◽  
Storm Impact

Abstract. Reefs and sand dunes are critical morphological features providing natural coastal protection. Reefs dissipate around 90 % of the incident wave energy through wave breaking, whereas sand dunes provide the final natural barrier against coastal flooding. The storm impact on coastal areas with these features depends on the relative elevation of the extreme water levels with respect to the sand dune morphology. However, despite the importance of barrier reefs and dunes in coastal protection, poor management practices have degraded these ecosystems, increasing their vulnerability to coastal flooding. The present study aims to theoretically investigate the role of the reef–dune system in coastal protection under current climatic conditions at Puerto Morelos, located in the Mexican Caribbean Sea, using a widely validated nonlinear non-hydrostatic numerical model (SWASH). Wave hindcast information, tidal level, and a measured beach profile of the reef–dune system in Puerto Morelos are employed to estimate extreme runup and the storm impact scale for current and theoretical scenarios. The numerical results show the importance of including the storm surge when predicting extreme water levels and also show that ecosystem degradation has important implications for coastal protection against storms with return periods of less than 10 years. The latter highlights the importance of conservation of the system as a mitigation measure to decrease coastal vulnerability and infrastructure losses in coastal areas in the short to medium term. Furthermore, the results are used to evaluate the applicability of runup parameterisations for beaches to reef environments. Numerical analysis of runup dynamics suggests that runup parameterisations for reef environments can be improved by including the fore reef slope. Therefore, future research to develop runup parameterisations incorporating reef geometry features (e.g. reef crest elevation, reef lagoon width, fore reef slope) is warranted.

scholarly journals EVALUATION AND DEVELOPMENT OF COASTAL PROTECTION MEASURES FOR SMALL ISLANDS IN THE WADDEN SEA

2014 ◽  
Vol 1 (34) ◽  
pp. 5 ◽  
Author(s):  
Theide Wöffler ◽  
Holger Schüttrumpf ◽  
Roger Häußling ◽  
Hilmar Von Eynatten ◽  
Arne Arns ◽  
...  
Keyword(s):  
Wadden Sea ◽  
Coastal Protection ◽  
Small Islands ◽  
Protection Measures

scholarly journals Twitter reveals human mobility dynamics during the COVID-19 pandemic

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0241957 ◽  
Author(s):  
Xiao Huang ◽  
Zhenlong Li ◽  
Yuqin Jiang ◽  
Xiaoming Li ◽  
Dwayne Porter
Keyword(s):  
Time Window ◽  
Human Mobility ◽  
Global Scale ◽  
Mitigation Measures ◽  
Mobility Patterns ◽  
Protection Measures ◽  
Social Challenges ◽  
Rapid Spread ◽  
Collaborative Efforts ◽  
State Scale

The current COVID-19 pandemic raises concerns worldwide, leading to serious health, economic, and social challenges. The rapid spread of the virus at a global scale highlights the need for a more harmonized, less privacy-concerning, easily accessible approach to monitoring the human mobility that has proven to be associated with viral transmission. In this study, we analyzed over 580 million tweets worldwide to see how global collaborative efforts in reducing human mobility are reflected from the user-generated information at the global, country, and U.S. state scale. Considering the multifaceted nature of mobility, we propose two types of distance: the single-day distance and the cross-day distance. To quantify the responsiveness in certain geographic regions, we further propose a mobility-based responsive index (MRI) that captures the overall degree of mobility changes within a time window. The results suggest that mobility patterns obtained from Twitter data are amenable to quantitatively reflect the mobility dynamics. Globally, the proposed two distances had greatly deviated from their baselines after March 11, 2020, when WHO declared COVID-19 as a pandemic. The considerably less periodicity after the declaration suggests that the protection measures have obviously affected people’s travel routines. The country scale comparisons reveal the discrepancies in responsiveness, evidenced by the contrasting mobility patterns in different epidemic phases. We find that the triggers of mobility changes correspond well with the national announcements of mitigation measures, proving that Twitter-based mobility implies the effectiveness of those measures. In the U.S., the influence of the COVID-19 pandemic on mobility is distinct. However, the impacts vary substantially among states.

Coastal protection measures, case study (Mediterranean zone, Egypt)

2015 ◽  
Vol 19 (3) ◽  
pp. 281-294 ◽  
Author(s):  
Ali Masria ◽  
Moheb Iskander ◽  
Abdelazim Negm
Keyword(s):  
Coastal Protection ◽  
Protection Measures

Numerical Investigation of Vertical Penetration of Steel Catenary Riser Near the Touch Down Zone

2016 ◽  
Author(s):  
Sujan Dutta ◽  
Bipul Hawlader ◽  
Ryan Phillips ◽  
Mike Paulin
Keyword(s):  
Soft Clay ◽  
Sea Waves ◽  
Factors Affecting ◽  
Steel Catenary Riser ◽  
Rate Dependent ◽  
Physical Experiments ◽  
Ansys Cfx ◽  
Waves And Currents ◽  
Steel Catenary Risers ◽  
Uplift Resistance

Steel catenary risers (SCR) are widely used in offshore to transport hydrocarbon from the seabed to floating or fixed platforms. The fatigue life of SCR near the touchdown zone (TDZ) is one of the main design concerns because the risers are often subjected to cyclic loading (vertical penetration/uplift, lateral and axial displacements) from various sources of environmental loadings, such as sea waves and currents. Numerical modeling of the penetration and uplift behaviour of an SCR is a challenging task. Most of the models available in the literature for uplift resistance are empirical, which have been developed mainly from the results of physical experiments. In this study, numerical simulation of vertical resistance is presented. Analysis is performed using ANSYS CFX software. Strain-softening and strain-rate dependent undrained shear strength behavior of soft clay sediment has been reported by many researchers. Unfortunately, these models were not available in CFX. Numerical simulations presented in this paper are performed implementing this behavior in CFX. Numerical results are compared with available empirical models. The present CFX modeling explains some mechanisms involved in trench formation and suction development during uplift. Factors affecting uplift resistance such as the size and shape of the trench are also discussed from a parametric study.

Sign in / Sign up

Export Citation Format

Share Document