Understanding Coastal Erosion on Beaches
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Coastal Erosion - Orrin H
COASTAL ZONES AND ESTUARIES – Coastal Erosion - Orrin H. Pilkey, William J. Neal, David M. Bush COASTAL EROSION Orrin H. Pilkey Program for the Study of Developed Shorelines, Division of Earth and Ocean Sciences, Duke University, Durham, NC, U.S.A. William J. Neal Department of Geology, Grand Valley State University, Allendale, MI, USA. David M. Bush Department of Geosciences, State University of West Georgia, Carrollton, GA, USA. Keywords: erosion, shoreline retreat, sea level rise, barrier islands, beach, coastal management, shoreline armoring, seawalls, sand supply Contents 1. Introduction 2. Causes of Erosion 2.1. Sea Level Rise 2.2. Sand Supply 2.3. Shoreline Engineering 2.4. Wave Energy and Storm Frequency 3. "Special" Cases 4. Solutions to Coastal Erosion 5. The Future Glossary Bibliography Biographical Sketches Summary Almost all of the world’s shorelines are retreating in a landward direction—a process called shoreline erosion. Sea level rise and the reduction of sand supply to the shoreline by damming of rivers, armoring of shorelines and the dredging of navigation channels are among the major causes of shoreline retreat. As sea levels continue to rise, sometimesUNESCO enhanced by subsidence caused – byEOLSS oil and water extraction, global erosion rates should increase in coming decades. Three response alternatives are available to "solve" the erosionSAMPLE problem. These are cons tructionCHAPTERS of seawalls and other engineering structures, beach nourishment and relocation or abandonment of buildings. No matter what path is chosen, response to the erosion problem is costly. 1. Introduction Coastal erosion is a major problem for developed shorelines everywhere in the world. Such erosion is regarded as a coastal hazard and is a common focus of local and national coastal management. -
Coastal Flood Defences - Groynes
Coastal Flood Defences - Groynes Coastal flood defences are key to protecting our coasts against flooding, which is when normally dry, low lying flat land is inundated by sea water. Hard engineering methods are forms of coastal flood defences which mitigate the risk of flooding and coastal erosion and the consequential effects. Hard Engineering Hard engineering methods are often used as a temporary measure to protect against coastal flooding as they are costly and only last for a relatively short amount of time before they require maintenance. However, they are very effective at protecting the coastline in the short-term as they are immediately effective as opposed to some longer term soft engineering methods. But they are often intrusive and can cause issues elsewhere at other areas along the coastline. Groynes are low lying wood or concrete structures which are situated out to sea from the shore. They are designed to trap sediment, dissipate wave energy and restrict the transfer of sediment away from the beach through long shore drift. Longshore drift is caused when prevailing winds blow waves across the shore at an angle which carries sediment along the beach.Groynes prevent this process and therefore, slow the process of erosion at the shore. They can also be permeable or impermeable, permeable groynes allow some sediment to pass through and some longshore drift to take place. However, impermeable groynes are solid and prevent the transfer of any sediment. Advantages and Disadvantages +Groynes are easy to construct. +They have long term durability and are low maintenance. +They reduce the need for the beach to be maintained through beach nourishment and the recycling of sand. -
Coastal Processes and Causes of Shoreline Erosion and Accretion Causes of Shoreline Erosion and Accretion
Coastal Processes and Causes of Shoreline Erosion and Accretion and Accretion Erosion Causes of Shoreline Heather Weitzner, Great Lakes Coastal Processes and Hazards Specialist Photo by Brittney Rogers, New York Sea Grant York Photo by Brittney Rogers, New New York Sea Grant Waves breaking on the eastern Lake Ontario shore. Wayne County Cooperative Extension A shoreline is a dynamic environment that evolves under the effects of both natural 1581 Route 88 North and human influences. Many areas along New York’s shorelines are naturally subject Newark, NY 14513-9739 315.331.8415 to erosion. Although human actions can impact the erosion process, natural coastal processes, such as wind, waves or ice movement are constantly eroding and/or building www.nyseagrant.org up the shoreline. This constant change may seem alarming, but erosion and accretion (build up of sediment) are natural phenomena experienced by the shoreline in a sort of give and take relationship. This relationship is of particular interest due to its impact on human uses and development of the shore. This fact sheet aims to introduce these processes and causes of erosion and accretion that affect New York’s shorelines. Waves New York’s Sea Grant Extension Program Wind-driven waves are a primary source of coastal erosion along the Great provides Equal Program and Lakes shorelines. Factors affecting wave height, period and length include: Equal Employment Opportunities in 1. Fetch: the distance the wind blows over open water association with Cornell Cooperative 2. Length of time the wind blows Extension, U.S. Department 3. Speed of the wind of Agriculture and 4. -
Management of Coastal Erosion by Creating Large-Scale and Small-Scale Sediment Cells
COASTAL EROSION CONTROL BASED ON THE CONCEPT OF SEDIMENT CELLS by L. C. van Rijn, www.leovanrijn-sediment.com, March 2013 1. Introduction Nearly all coastal states have to deal with the problem of coastal erosion. Coastal erosion and accretion has always existed and these processes have contributed to the shaping of the present coastlines. However, coastal erosion now is largely intensified due to human activities. Presently, the total coastal area (including houses and buildings) lost in Europe due to marine erosion is estimated to be about 15 km2 per year. The annual cost of mitigation measures is estimated to be about 3 billion euros per year (EUROSION Study, European Commission, 2004), which is not acceptable. Although engineering projects are aimed at solving the erosion problems, it has long been known that these projects can also contribute to creating problems at other nearby locations (side effects). Dramatic examples of side effects are presented by Douglas et al. (The amount of sand removed from America’s beaches by engineering works, Coastal Sediments, 2003), who state that about 1 billion m3 (109 m3) of sand are removed from the beaches of America by engineering works during the past century. The EUROSION study (2004) recommends to deal with coastal erosion by restoring the overall sediment balance on the scale of coastal cells, which are defined as coastal compartments containing the complete cycle of erosion, deposition, sediment sources and sinks and the transport paths involved. Each cell should have sufficient sediment reservoirs (sources of sediment) in the form of buffer zones between the land and the sea and sediment stocks in the nearshore and offshore coastal zones to compensate by natural or artificial processes (nourishment) for sea level rise effects and human-induced erosional effects leading to an overall favourable sediment status. -
Geology of Hawaii Reefs
11 Geology of Hawaii Reefs Charles H. Fletcher, Chris Bochicchio, Chris L. Conger, Mary S. Engels, Eden J. Feirstein, Neil Frazer, Craig R. Glenn, Richard W. Grigg, Eric E. Grossman, Jodi N. Harney, Ebitari Isoun, Colin V. Murray-Wallace, John J. Rooney, Ken H. Rubin, Clark E. Sherman, and Sean Vitousek 11.1 Geologic Framework The eight main islands in the state: Hawaii, Maui, Kahoolawe , Lanai , Molokai , Oahu , Kauai , of the Hawaii Islands and Niihau , make up 99% of the land area of the Hawaii Archipelago. The remainder comprises 11.1.1 Introduction 124 small volcanic and carbonate islets offshore The Hawaii hot spot lies in the mantle under, or of the main islands, and to the northwest. Each just to the south of, the Big Island of Hawaii. Two main island is the top of one or more massive active subaerial volcanoes and one active submarine shield volcanoes (named after their long low pro- volcano reveal its productivity. Centrally located on file like a warriors shield) extending thousands of the Pacific Plate, the hot spot is the source of the meters to the seafloor below. Mauna Kea , on the Hawaii Island Archipelago and its northern arm, the island of Hawaii, stands 4,200 m above sea level Emperor Seamount Chain (Fig. 11.1). and 9,450 m from seafloor to summit, taller than This system of high volcanic islands and asso- any other mountain on Earth from base to peak. ciated reefs, banks, atolls, sandy shoals, and Mauna Loa , the “long” mountain, is the most seamounts spans over 30° of latitude across the massive single topographic feature on the planet. -
Coastal Zone and Estuaries
CONTENTS COASTAL ZONE AND ESTUARIES Coastal Zone and Estuaries - Volume 1 No. of Pages: 540 ISBN: 978-1-84826-016-0 (eBook) ISBN: 978-1-84826-466-3 (Print Volume) For more information of e-book and Print Volume(s) order, please click here Or contact : [email protected] ©Encyclopedia of Life Support Systems (EOLSS) COASTAL ZONES AND ESTUARIES CONTENTS Coastal Zone and Estuaries 1 Federico Ignacio Isla, Centro de Geología de Costas y del Cuaternario, Universidad Nacional de Mar del Plata, Argentina 1. The Coastal Zone 1.1. Climate Change 1.2. Sea Level and Sea Ice Fluctuations 1.3. Coastal Processes 1.4. Sediment Delivery 1.5. Beaches 1.6. Tidal Flats and Marshes 1.7. Mangroves 1.8. Coral Reefs, Coral Cays, Sea Grasses, and Seaweeds 1.9. Eutrophication and Pollution 1.10. Coastal Evolution 2. Estuarine Environments 2.1. Estuaries 2.2. Coastal Lagoons 2.3. Deltas 2.4. Estuarine Evolution 3. Coastal Management 4. New Techniques in Coastal Science 5. Concluding Remarks Coastal Erosion 32 Orrin H. Pilkey, Program for the Study of Developed Shorelines, Division of Earth and Ocean Sciences, Duke University, Durham, NC, U.S.A. William J. Neal, Department of Geology, Grand Valley State University, Allendale, MI, USA. David M. Bush, Department of Geosciences, State University of West Georgia, Carrollton, GA, USA. 1. Introduction 2. Causes of Erosion 2.1. Sea Level Rise 2.2. Sand Supply 2.3. Shoreline Engineering 2.4. Wave Energy and Storm Frequency 3. Special Cases 4. Solutions to Coastal Erosion 5. The Future Waves and Sediment Transport in the Nearshore Zone 43 Robin G. -
The Emergence of Magnetic Skyrmions
The emergence of magnetic skyrmions During the past decade, axisymmetric two-dimensional solitons (so-called magnetic skyrmions) have been discovered in several materials. These nanometer-scale chiral objects are being proposed as candidates for novel technological applications, including high-density memory, logic circuits and neuro-inspired computing. Alexei N. Bogdanov and Christos Panagopoulos Research on magnetic skyrmions benefited from a cascade of breakthroughs in magnetism and nonlinear physics. These magnetic objects are believed to be nanometers-size whirling cylinders, embedded into a magnetically saturated state and magnetized antiparallel along their axis (Fig. 1). They are topologically stable, in the sense that they can’t be continuously transformed into homogeneous state. Being highly mobile and the smallest magnetic configurations, skyrmions are promising for applications in the emerging field of spintronics, wherein information is carried by the electron spin further to, or instead of the electron charge. Expectedly, their scientific and technological relevance is fueling inventive research in novel classes of bulk magnetic materials and synthetic architectures [1, 2]. The unconventional and useful features of magnetic skyrmions have become focus of attention in the science and technology Figure 1. Magnetic skyrmions are nanoscale spinning magnetic circles, sometimes teasingly called “magic knots” or “mysterious cylinders (a), embedded into the saturated state of ferromagnets (b). particles”. Interestingly, for a long time it remained widely In the skyrmion core, magnetization gradually rotates along radial unknown that the key “mystery” surrounding skyrmions is in the directions with a fixed rotation sense namely, from antiparallel very fact of their existence. Indeed, mathematically the majority of direction at the axis to a parallel direction at large distances from the physical systems with localized structures similar to skyrmions are center. -
Types and Causes of Beach Erosion Anomaly Areas in the U.S. East Coast Barrier Island System: Stabilized Tidal Inlets
Middle States Geographer, 2007, 40:158-170 TYPES AND CAUSES OF BEACH EROSION ANOMALY AREAS IN THE U.S. EAST COAST BARRIER ISLAND SYSTEM: STABILIZED TIDAL INLETS Francis A. Galgano Jr. Department of Geography and the Environment Villanova University 800 Lancaster Avenue Villanova, Pennsylvania 19085 ABSTRACT: Contemporary research suggests that most U.S. beaches are eroding, and this has become an important political and economic issue because beachfront development is increasingly at risk. In fact, the Heinz Center and Federal Emergency Management Agency (FEMA) estimate that over the next 60 years, beach erosion may claim one out of four homes within 150 meters of the U.S. shoreline. This is significant because approximately 350,000 structures are located with 150 meters of the shoreline in the lower 48 states, not including densely populated coastal cities such as New York and Miami. Along the East Coast, most beaches are eroding at 1 to 1.5 meters per year. However, beach erosion is especially problematic along so-called beach erosion anomaly areas (EAAs) where erosion rates can be as much as five times the rate along adjacent beaches. Identifying and understanding these places is important because property values along U.S. East Coast barrier islands are estimated to be in the trillions of dollars, and the resultant beach erosion may also destroy irreplaceable habitat. There are a number of factors⎯natural and anthropogenic⎯that cause beaches to erode at anomalous rates. This paper will focus on the barrier island system of the U.S. East Coast, classify beach EAAs, and examine beach erosion down drift from stabilized tidal inlets because they are perhaps the most spatially extensive and destructive EAAs. -
Evaluation of the Coastal Inundation and Erosion Process in the Mid-West Coast of Western Australia
Faculty of Science and Engineering School of Civil and Mechanical Engineering Evaluation of the coastal inundation and erosion process in the Mid-West coast of Western Australia Withanage Sajantha Lakmali Perera This thesis is presented for the Degree of Master of Philosophy (Civil Engineering) of Curtin University September 2016 Abstract At present the coastal inundation and erosion is a major problem all around the world and this issue will be more severe in the future due to sea level rise. Australia has a long coastline around the country, thus it focus on the coastal vulnerability due to sea level rise. Taking these facts into account, this research was focused on the evaluation of the coastal inundation and erosion process in the Mid-West coast of Western Australia. Within the Mid-West region, a seventy five kilometre stretch was selected for the study. The major highlight of this research is the integrated modelling approach and the result of the modelling carried out for evaluation of the coastal inundation and erosion process. Widely used coastal model, MIKE 21 was selected as the dynamic model for the study. As data plays very important part for this research, an intensive data collection campaign was conducted to collect the required data. Bathymetry data, coastal boundary data, topography data, wave, water levels and wind data, were collected using discrete data sources from variety of government, local and private organizations. Extreme value analysis for water levels, wind and wave was done using Gumbel and Weibull distributions. The final results of the inundation and erosion extends have been presented in terms of spatial maps. -
This Content Is Prepared from Various Sources and Has Used the Study Material from Various Books, Internet Articles Etc
This content is prepared from various sources and has used the study material from various books, internet articles etc. The teacher doesn’t claim any right over the content, it’s originality and any copyright. It is given only to the students of PG course in Geology to study as a part of their curriculum. WAVES Waves and their properties. (a) Regular, symmetrical waves can be described by their height, wavelength, and period (the time one wavelength takes to pass a fixed point). (b) Waves can be classified according to their wave period. The scales of wave height and wave period are not linear, but logarithmic, being based on powers of 10. The variety and size of wind-generated waves are controlled by four principal factors: (1) wind velocity, (2) wind duration, (3) fetch, (4) original sea state. Significant Wave Height? What is the average height and what is the significant height? Wind-generated waves are progressive waves, because they travel (progress) across the sea surface. If you focus on the crest of a progressive wave, you can follow its path over time. But what actually is moving? The wave form obviously is moving, but what about the water just below the sea surface? Actually, two basic kinds of motions are associated with ocean waves: the forward movement of the wave form itself and the orbital motion of water particles beneath the wave. The motion of water particles beneath waves. (a) The arrows at the sea surface denote the motion of water particles beneath waves. With the passage of one wavelength, a water particle at the sea surface describes a circular orbit with a diameter equal to the wave’s height. -
A Guide to the Birds of Barrow Island
A Guide to the Birds of Barrow Island Operated by Chevron Australia This document has been printed by a Sustainable Green Printer on stock that is certified carbon in joint venture with neutral and is Forestry Stewardship Council (FSC) mix certified, ensuring fibres are sourced from certified and well managed forests. The stock 55% recycled (30% pre consumer, 25% post- Cert no. L2/0011.2010 consumer) and has an ISO 14001 Environmental Certification. ISBN 978-0-9871120-1-9 Gorgon Project Osaka Gas | Tokyo Gas | Chubu Electric Power Chevron’s Policy on Working in Sensitive Areas Protecting the safety and health of people and the environment is a Chevron core value. About the Authors Therefore, we: • Strive to design our facilities and conduct our operations to avoid adverse impacts to human health and to operate in an environmentally sound, reliable and Dr Dorian Moro efficient manner. • Conduct our operations responsibly in all areas, including environments with sensitive Dorian Moro works for Chevron Australia as the Terrestrial Ecologist biological characteristics. in the Australasia Strategic Business Unit. His Bachelor of Science Chevron strives to avoid or reduce significant risks and impacts our projects and (Hons) studies at La Trobe University (Victoria), focused on small operations may pose to sensitive species, habitats and ecosystems. This means that we: mammal communities in coastal areas of Victoria. His PhD (University • Integrate biodiversity into our business decision-making and management through our of Western Australia) -
1 the Influence of Groyne Fields and Other Hard Defences on the Shoreline Configuration
1 The Influence of Groyne Fields and Other Hard Defences on the Shoreline Configuration 2 of Soft Cliff Coastlines 3 4 Sally Brown1*, Max Barton1, Robert J Nicholls1 5 6 1. Faculty of Engineering and the Environment, University of Southampton, 7 University Road, Highfield, Southampton, UK. S017 1BJ. 8 9 * Sally Brown ([email protected], Telephone: +44(0)2380 594796). 10 11 Abstract: Building defences, such as groynes, on eroding soft cliff coastlines alters the 12 sediment budget, changing the shoreline configuration adjacent to defences. On the 13 down-drift side, the coastline is set-back. This is often believed to be caused by increased 14 erosion via the ‘terminal groyne effect’, resulting in rapid land loss. This paper examines 15 whether the terminal groyne effect always occurs down-drift post defence construction 16 (i.e. whether or not the retreat rate increases down-drift) through case study analysis. 17 18 Nine cases were analysed at Holderness and Christchurch Bay, England. Seven out of 19 nine sites experienced an increase in down-drift retreat rates. For the two remaining sites, 20 retreat rates remained constant after construction, probably as a sediment deficit already 21 existed prior to construction or as sediment movement was restricted further down-drift. 22 For these two sites, a set-back still evolved, leading to the erroneous perception that a 23 terminal groyne effect had developed. Additionally, seven of the nine sites developed a 24 set back up-drift of the initial groyne, leading to the defended sections of coast acting as 1 25 a hard headland, inhabiting long-shore drift.