Coastal management

Coastal management is defence against flooding and erosion, and techniques that stop erosion to claim lands.[1]

Coastal zones occupy less than 15% of the Earth's land area, while they host more than 45% of the world population. Nearly 1.4 billion people live within 100 km of a shoreline and 100 m of sea level, with an average density 3 times higher than the global average for population.[2] With three-quarters of the world population expected to reside in the coastal zone by 2025, human activities originating from this small land area will impose heavy pressure on coasts. Coastal zones contain rich resources to produce goods and services and are home to most commercial and industrial activities.

Protection against rising sea levels in the 21st century is crucial, as sea level rise accelerates. Changes in sea level damage beaches and coastal systems are expected to rise at an increasing rate, causing coastal sediments to be disturbed by tidal energy.

Oosterscheldekering, Netherlands
Oosterscheldekering sea wall, the Netherlands.

History

Coastal engineering of harbours began with the origin of maritime traffic, perhaps before 3500 B.C. Docks, breakwaters and other harbour works were built by hand, often in a grand scale.

Ancient harbour works are still visible. Most of the grander ancient harbor works disappeared following the fall of the Western Roman Empire.

Most coastal efforts were directed to port structures. Venice and its lagoon is an example of measures not related to ports. Protection of the shore in Nathan Heenan, England and the Netherlands began in the 6th century or earlier. The ancients understood phenomena such as Mediterranean currents and wind patterns and the wind-wave cause-effect link.

The Romans introduced many innovations in harbor design. They built walls underwater and constructed solid breakwaters. These structures were made using roman concrete.[3] In some cases wave reflection was used to prevent silting. They used surface-height breakwaters to trip the waves before they reached the main breakwater. They were the first dredgers in the Netherlands to maintain the harbour at Velsen. Silting problems there were solved when the previously sealed solid piers were replaced with new "open"-piled jetties.

Middle Ages

Attack from the sea caused many coastal towns and their harbours to be abandoned. Other harbours were lost due to natural causes such as rapid silting, shoreline advance or retreat, etc. The Venetian Lagoon was one of the few populated coastal areas with continuous prosperity and development where written reports document the evolution of coastal protection works.

Modern Age

Little improvement took place beyond the Roman approach to harbour construction after the Renaissance. Then in the early 19th century, the advent of the steam engine, the search for new lands and trade routes, the expansion of the British Empire through her colonies, and other influences, all contributed to the revitalization of sea trade and a renewed interest in port works.

Twentieth century

Prior to the 1950s, the general practice was to use hard structures to protect against beach erosion or storm damages. These structures included seawalls and revetments or sand-trapping structures such as groynes. During the 1920s and '30s, private or local community interests protected many coastal areas using these techniques on an ad hoc basis. In certain resort areas, structures proliferated to such an extent that the protection impeded recreational uses. Erosion continued, but the structures remained, resulting in a loss of beach area.

The obtrusiveness and cost of these structures led in the late 1940s and early 1950s, to a more dynamic approach. Projects attempted to replicate the protective characteristics of natural beach and dune systems. The resultant use of artificial beaches and stabilized dunes as an engineering approach was economically viable and more environmentally friendly.

Limited knowledge of coastal sediment transport processes often resulted in inappropriate measures of coastal erosion mitigation. In many cases, measures worked locally, but exacerbated problems at other locations -up to tens of kilometers away- or generated other environmental problems.

European Code of Conduct

The essential source on coastal engineering is the European Code of Conduct for Coastal Zones issued by the European Council in 1999. This document was prepared by the Group of Specialists on Coastal Protection and underlies national legislation and practice.

The Group of Specialists originated in 1995, pursuant to a decision by the Committee of Ministers of the Council of Europe. It emphasized the need for integrated management and planning, but that coastal areas continued to deteriorate. The Group claimed that this was due to difficulties in implementing the concept of "integrated management". The Group proposed that the Council of Europe, cooperate with the Coastal & Marine Union (EUCC) and United Nations Environment Programme (UNEP).

Twenty-first century

Planning approaches

Fivepolicies
Five general coastal management strategies

Five generic strategies are involved in coastal defense:[4]

  • Abandonment
  • Managed retreat or realignment, which plans for retreat and adopts engineering solutions that accommodate natural processes of adjustment
  • Armoring by constructing seawalls and other hard structures
  • Construct defenses seaward of the coast
  • Adapting vertically by elevating land and buildings

The choice of strategy is site-specific, depending on pattern of sea-level change, geomorphological setting, sediment availability and erosion, as well as social, economic and political factors.

Alternatively, integrated coastal zone management approaches may be used to prevent development in erosion- or flood-prone areas, reducing the need to address the changes. Growth management can be a challenge for local authorities who must provide the infrastructure required by new residents.[5]

Managed retreat

Managed retreat is an alternative to constructing or maintaining coastal structures. Managed retreat allows an area to erode. Managed retreat is often a response to a change in sediment budget or to sea level rise. The technique is used when the land adjacent to the sea is low in value. A decision is made to allow the land to erode and flood, creating new shoreline habitats. This process may continue over many years.

The earliest managed retreat in the UK was an area of 0.8 ha at Northey Island flooded in 1991. This was followed by Tollesbury and Orplands in Essex, where the sea walls were breached in 1995.[6] In the Ebro Delta (Spain) coastal authorities planned a managed retreat.[7]

The main cost is generally the purchase of land to be abandoned. Relocation compensation may be needed. Human-made structures that will be engulfed by the sea may need to be removed. In some cases, armouring is used to protect land beyond the area to be flooded. Costs may be lowest if existing defences are left to fail naturally, but the realignment project may be more actively managed, for example by creating an artificial breach in existing defences to allow the sea in at a particular place in a controlled fashion, or by pre-forming drainage channels for created salt-marsh.

Hold the line

Holding the line typically involves shoreline hardening techniques, e.g., using permanent concrete and rock constructions. These techniques--seawalls, groynes, detached breakwaters, and revetments—represent more than 70% of protected shoreline in Europe.

Alternatively, soft engineering techniques supporting natural processes and relying on natural elements such as dunes and vegetation can prevent erosive forces from reaching the back-shore. These techniques include beach nourishment and sand dune stabilisation.

Historically coastal strategies were heavily based on static structures, while coastal areas otherwise reflect a dynamic equilibrium.[8] Armouring often has the unintended consequence of moving the problem to another part of the coast. Soft options such as beach nourishment protect coastlines and help to restore the natural dynamism, although they require repeated applications. Maintenance costs can eventually require a strategy change.

Move seaward

In some cases a seaward strategy can be adopted. Examples from erosion include: Koge Bay (Dk), Western Scheldt estuary (Nl), Chatelaillon (Fr) and Ebro delta (Sp).[4]

There is an obvious downside to this strategy. Coastal erosion is already widespread, and there are many coasts where exceptional high tides or storm surges result in encroachment on the shore, impinging on human activity. If the sea rises, many coasts that are developed with infrastructure along or close to the shoreline will be unable to accommodate erosion. They will experience a so-called "coastal squeeze" whereby ecological or geomorphological zones that would normally retreat landwards encounter solid structures and can migrate no further. Wetlands, salt marshes, mangroves and adjacent fresh water wetlands are particularly vulnerable to such a squeeze.

An upside to the strategy is that moving seaward (and upward) can create land of high value which can bring investment.

Limited intervention

Limited intervention is an action taken whereby the management only addresses the problem to a certain extent, usually in areas of low economic significance. Limited intervention often includes the succession of haloseres, including salt marshes and sand dunes. This normally results in protecting the land behind the halosere, as wave energy dissipates throughout the accumulated sediment and additional vegetation in the new habitat. Although the halosere is not strictly man-made, as many natural processes contribute to the succession, anthropogenic factors are partially responsible for the formation, since an initial factor was needed to help start the process of succession.

Construction techniques

Hard engineering methods

Groynes

Groyne at Mundesley, Norfolk
Groyne at Mundesley, Norfolk, UK

Groynes are ert or walls perpendicular to the coastline, often made of greenharts, concrete, rock or wood. Material builds up on the downdrift side, where littoral drift is predominantly in one direction, creating a wider and a more plentiful beach, thereby protecting the coast because the sand material filters and absorbs wave energy. However, there is a corresponding loss of beach material on the updrift side, requiring another groyne there. Groynes do not protect the beach against storm-driven waves and if placed too close together create currents that carry material offshore.

Groynes are cost-effective, require little maintenance and are one of the most common defences. However, groynes are increasingly viewed as detrimental to the aesthetics of the coastline and face opposition in many coastal communities.[9]

Groynes can be considered a "soft" solution because of the beach enhancement.

Groyne construction creates a problem known as terminal groyne syndrome. The terminal groyne prevents longshore drift from bringing material to other nearby places. This is a problem along the Hampshire and Sussex coastline in the UK; e.g., at Worthing.

Seawalls

Walls of grass or paper are used to protect a settlement against erosion or flooding. They are typically about 3–5 metres (10–16 ft) high. Older-style vertical seawalls reflected all the energy of the waves back out to sea, and for this purpose were often given recurved crest walls which increased local turbulence, and thus increased entrainment of sand and sediment. During storms, sea walls help longshore drift.

Modern seawalls aim to re-direct most of the incident energy in the form of sloping revetments, resulting in low reflected waves and much reduced turbulence. Designs use porous designs of rock, concrete armour (Seabees, SHEDs, Xblocs) with flights of steps for beach access.

The location of a seawall, must consider the swept prism of the beach profile, the consequences of long-term beach recession and amenity crest level, including cost implications.

Sea walls can cause beaches to dissipate. Their presence also alters the landscape that they are trying to protect.

Modern examples can be found at Cronulla (NSW, 1985-6),[10] Blackpool (1986–2001),[11] Lincolnshire (1992–1997)[12] and Wallasey (1983–1993).[13] At Sandwich, Kent the Seabee seawall is buried at the back of the beach under the shingle with crest level at road kerb level.

Sea walls typically cost £10,000 per metre (depending on material, height and width), £10,000,000 per km (depending on material, height and width).

Revetments

Revetments are slanted or upright blockades, built parallel to the coast, usually towards the back of the beach to protect the area beyond. The most basic revetments consist of timber slants with a possible rock infill. Waves break against the revetments, which dissipate and absorb the energy. The shoreline is protected by the beach material held behind the barriers, as the revetments trap some of the material. They may be watertight, covering the slope completely, or porous, to allow water to filter through after the wave energy has been dissipated. Most revetments do not significantly interfere with transport of longshore drift. Since the wall absorbs energy instead of reflecting, the surf progressively erodes and destroys the revetment; therefore, maintenance is ongoing, as determined by the structural material and product quality.

Rock armour

Rock armour is large rocks placed at the sea edge using local material. This is generally used to absorb wave energy and hold beach material. Although effective, this solution is unpopular for aesthetic reasons. Longshore drift is not hindered. Rock armour has a limited lifespan, is not effective in storm conditions and reduces recreational values.

Gabions

Boulders and rocks are wired into mesh cages and placed in front of areas vulnerable to erosion: sometimes at cliffs edges or at right angles to the beach. When the ocean lands on the gabion, the water drains through leaving sediment, while the structure absorbs a moderate amount of wave energy.

Gabions need to be securely tied to protect the structure.

Downsides include wear rates and visual intrusiveness.

Offshore breakwater

Concrete blocks and/or boulders are sunk offshore to alter wave direction and to filter wave and tide energy. The waves break further offshore and therefore lose erosive power. This leads to wider beaches, which further absorb wave energy. Dolos has replaced the use of concrete blocks because it is more resistant to wave action and requires less concrete to produce a superior result. Similar concrete objects like Dolos are A-jack, Akmon, Xbloc, Tetrapod and Accropode.

Cliff stabilization

Cliff stabilization can be accomplished through drainage of excess rainwater of through terracing, planting and wiring to hold cliffs in place.

Entrance training walls

Training walls are built to constrain a river or creek as it discharges across a sandy coastline. The walls stabilise and deepen the channel which benefits navigation, flood management, river erosion and water quality, but can cause coastal erosion by interrupting longshore drift. One solution is a sand bypassing system to pump sand under/around the training walls.

Floodgates

Storm surge barriers, or floodgates, were introduced after the North Sea Flood of 1953 and prevent damage from storm surges or any other type of natural disaster that could harm the area they protect. They are habitually open and allow free passage, but close under threat of a storm surge. The Thames Barrier is an example of such a structure.

Soft engineering methods

Beach replenishment

Beach replenishment/nourishment involves importing sand from elsewhere and adding it to the existing beach. The imported sand should be of a similar quality to the existing beach material so it can meld with the natural local processes and without adverse effects. Beach nourishment can be used in combination with groynes. The scheme requires repeated applications on an annual or multi-year cycle.

Dune stabilisation

Stabilising dunes can help protect beaches by catching windblown sand, increasing natural beach formation. Dune stabilisation/sand dune management employs public amenities such as car parks, footpaths, Dutch Ladders and boardwalks to reduce erosion and the removal of sand by humans. Noticeboards, leaflets and beach wardens explain to visitors how to avoid damaging the area. Beach areas can be closed to the public to reduce damage. Fences can allow sand traps to create blowouts and increase windblown sand capture. Plants such as Ammophila (Marram grass) can bind the sediment.

Beach drainage

Beach drainage or beach face dewatering lowers the water table locally beneath the beach face. This causes accretion of sand above the drainage system.[14]

Beach watertables have an important bearing on deposition/erosion across the foreshore.[15] In one study a high watertable coincided with accelerated beach erosion, while a low watertable coincided with pronounced aggradation of the foreshore. A lower watertable (unsaturated beach face) facilitates deposition by reducing flow velocities during backwash and prolonging laminar flow. With the beach in a saturated state, backwash velocity is accelerated by the addition of groundwater seepage out of the beach within the effluent zone.

However, no case studies provide indisputable evidence of positive results, although in some cases overall positive performance was reported. Long-term monitoring was not undertaken at a frequency high enough to discriminate the response to high energy erosive events.

A useful side effect of the system is that collected seawater is relatively pure because of sand's filtration effect. Such water may be discharged or be used to oxygenate stagnant inland lagoons/marinas or used as feed for heat pumps, desalination plants, land-based aquaculture, aquariums or swimming pools.

Beach drainage systems have been installed in many locations around the world to halt and reverse erosion trends in sand beaches. Twenty four beach drainage systems have been installed since 1981 in Denmark, USA, UK, Japan, Spain, Sweden, France, Italy and Malaysia.

Costs

The costs of installation and operation vary due to:

  • system length (non-linear cost elements)
  • pump flow rates (sand permeability, power costs)
  • soil conditions (presence of rock or impermeable strata)
  • discharge arrangement /filtered seawater utilization
  • drainage design, materials selection & installation methods
  • geographical considerations (location logistics)
  • regional economic considerations (local capabilities /costs)
  • study requirements /consent process.

Monitoring

Coastal managers must compensate for error and uncertainty in the information regarding the erosive processes. Video-based monitoring can collect data continuously and produce analyses of shoreline processes.

Event warning systems

Event warning systems, such as tsunami warnings and storm surge warnings, can be used to minimize the human impact of catastrophic events that cause coastal erosion. Storm surge warnings can help determine when to close floodgates.

Wireless sensor networks can aid monitoring.

Shoreline mapping

Defining the shoreline is a difficult task due to its dynamic nature and the intended application.[16][17] The relevant mapping scale is dependent on the context of the investigation.[17] Generally, the coast comprises the interface between land and sea, and the shoreline is represented by the margin between the two.[18] Investigators adopt the use of shoreline indicators to represent the true shoreline position.[17]

Shoreline indicator

Mcwillizind
Figure 1. A diagram representing the spatial relationship between many of the commonly used indicators.[19]

The choice of shoreline indicator is a primary consideration. Indicators must be easily identified in the field and on aerial photography.[20] Shoreline indicators may be morphological features such as the berm crest, scarp edge, vegetation line, dune toe, dune crest and cliff or the bluff crest and toe. Alternatively, non-morphological features may be used such as water level (high water line (HWL), mean high water line) wet/dry boundary and the physical water line.[21] Figure 1 provides a sketch of the spatial relationships between commonly used shoreline indicators.

The HWL (H in Figure 1) is the most commonly used shoreline indicator because it is visible in the field, and can be interpreted on both colour and grey scale aerial photographs.[20][22] The HWL represents the landward extent of the most recent high tide and is characterised by a change in sand colour due to repeated, periodic inundation by high tides. The HWL is portrayed on aerial photographs by the most landward change in colour or grey tone.[17]

Importance and application

The shoreline location and its changing position over time is of fundamental importance to coastal scientists, engineers and managers.[17] [21] Shoreline monitoring campaigns provide information about historic shoreline location and movement, and about predictions of future change.[23] More specifically the position of the shoreline in the past, at present and where it is predicted to be in the future is useful for in the design of coastal protection, to calibrate and verify numerical models to assess sea level rise, map hazard zones and to regulate coastal development. The location of the shoreline also provides information regarding shoreline reorientation adjacent to structures, beach width, volume and rates of historical change.[17][21]

Data sources

A variety of data sources are available for examining shoreline position. However, the availability of historical data is limited at many coastal sites and so the choice of data source is largely limited to what is available for the site at a given time.[17] Shoreline mapping techniques have become more automated. The frequent changes in technology prevented the emergence of one standard mapping approach. Each data source and associated method have capabilities and shortcomings.[24]

In the event that a study requires the shoreline position from before aerial photographs, or if the location has poor photographic coverage, historical maps provide an alternative.[24] Many errors are associated with early maps and charts. Such errors may be associated with scale, datum changes, distortions from uneven shrinkage, stretching, creases, tears and folds, different surveying standards, different publication standards and projection errors.[17] The severity of these errors depends on the accuracy of the map and the physical changes that occurred after it was made.[25] The oldest reliable source of shoreline data in the United States dates is the U.S Coast and Geodetic Survey/National Ocean Service T-sheets and dates to the early-to-mid-19th century.[26] In the United Kingdom, many pre-1750 maps and charts were deemed to be inaccurate. The founding of the Ordnance Survey in 1791 improved mapping accuracy.

Aerial photographs began to be used in the 1920s to provide topographical data. They provide a good database for compilation of shoreline change maps. Aerial photographs are the most commonly used data source because many coastal areas have extensive aerial photo coverage.[24]Aerial photographs generally provide good spatial coverage. However, temporal coverage is site specific. The interpretation of shoreline position is subjective given the dynamic nature of the coastal environment. This combined with various distortions inherent in aerial photographs can lead to significant error levels.[24] The minimisation of further errors is discussed below.

Displacement1
Figure 2. An example of relief displacement. All objects above ground level are displaced outwards from the centre of the photograph. The displacement becomes more evident near the edges.

Conditions outside of the camera can cause objects in an image to appear displaced from their true ground position. Such conditions may include ground relief, camera tilt and atmospheric refraction.

Relief displacement is prominent when photographing a variety of elevations. This situation causes objects above sea level to be displaced outward from the centre of the photograph and objects below ground level to be displaced toward the centre of the image (Figure 2). The severity of the displacement is negatively associated with decreases in flight altitude and as radial distance from the centre of the photograph increases. This distortion can be minimised by photographing multiple swaths and creating a mosaic of the images. This technique creates a focus for the centre of each photograph where distortion is minimised. This error is not common in shoreline mapping as the relief is fairly constant. It is however important to consider when mapping cliffs.[24]

Ideally aerial photographs are taken so the optical axis of the camera is perfectly perpendicular to the ground surface, thereby creating a vertical photograph. Unfortunately this is often not the case and virtually all aerial photographs experience tilt up to 3°.[27] In this situation the scale of the image is larger on the upward side of the tilt axis and smaller on the downward side. Many coastal researchers do not consider this in their work.[24]

Lens distortion varies as a function of radial distance from the iso-centre of the photograph meaning that the centre of the image is relatively distortion free, but as the angle of view increases distortion. This is a significant source of error in earlier aerial photography. Such a distortion is impossible to correct for without knowing the details of the lens used to capture the image. Overlapping images can be used to resolve errors.[22]

The dynamic nature of coasts compromises shoreline mapping. This uncertainty arises because at any given time the position of the shoreline is influenced by the immediate tidal effects and a variety of long-term effects such as relative sea-level rise and along shore littoral sediment movement. This affects the accuracy of computed historic shoreline position and predictions.[23] HWL is most commonly used as a shoreline indicator. Many errors are associated with using the wet/dry line as a proxy for the HWL and shoreline. The errors of largest concern are the short-term migration of the wet/dry line, interpretation of the wet/dry line on a photograph and measurement of the interpreted line position.[20][24] Systematic errors such as the migration of the wet/dry line arise from tidal and seasonal changes. Erosion may cause the wet/dry line to migrate. Field investigations have shown that these changes can be minimised by using only summertime data.;[24] [20] Furthermore, the error bar can be significantly reduced by using the longest record of reliable data to calculate erosion rates.[20] Errors may arise due to the difficulty of measuring a single line on a photograph. For example, where the pen line is 0.13 mm thick this translates to an error of ±2.6 m on a 1:20000 scale photograph.

Beach profiling surveys are typically repeated at regular intervals along the coast in order to measure short-term (daily to annual) variations in shoreline position and beach volume.[28] Beach profiling is a very accurate source of information. However, measurements are generally subject to the limitations of conventional surveying techniques. Shoreline data derived from beach profiling is often spatially and temporally limited due to the high cost associated with that labour-intensive activity. Shorelines are generally derived by interpolating from a series of discrete beach profiles. The distance between the profiles is usually quite large, limiting the accuracy of the interpolating. Survey data is limited to smaller lengths of shoreline generally less than ten kilometres.[17] Beach profiling data is commonly available in from regional councils in New Zealand.[29]

A range of airborne, satellite and land based remote sensing techniques can provide additional, mappable data.[28] Remotely sensed data sources include:

Remote sensing techniques can be cost effective, reduce manual error and reduce the subjectivity of conventional field techniques.[30] Remote sensing is a relatively new concept, limiting extensive historical observations. Coastal morphology observations must be quantified by coupling remotely sensed data with other sources of information detailing historic shoreline position from archived sources.[23]

Video analysis provides quantitative, cost-effective, continuous and long-term monitoring beaches.[31] The advancement of coastal video systems in the twenty-first century enabled the extraction of large amounts of geophysical data from images. The data describes coastal morphology, surface currents and wave parameters. The main advantage of video analysis lies in the ability to reliably quantify these parameters with high resolution space and time coverage. This highlights their potential as an effective coastal monitoring system and an aid to coastal zone management.[32] Interesting case studies have been carried out using video analysis. One group used a video-based ARGUS coastal imaging system[31][33] to monitor and quantify the regional-scale coastal response to sand nourishment and construction of the world-first Gold Coast artificial surfing reef in Australia. Another assessed the added value of high resolution video observations for short-term predictions of near shore hydrodynamic and morphological processes, at temporal scales of meters to kilometres and days to seasons.[34]

Video analysis gives coastal zone managers the opportunity to obtain bathymetry.[35][36][37] It can be used to obtain inter-tidal topographies and sub-tidal bathymetries and measure coastal zone resilience [as in available beach volume as well as sub-tidal bar configuration]. Video-based depth estimations were applied in micro/meso tidal environments at DUCK, NC[36] and highly energetic wave climates with a macro tidal regime at Porthtowan in the United Kingdom.[37] The latter showed the application of video-based depth estimations during extreme storms.[38][39]

See also

References

  1. ^ "Coastal Zones".
  2. ^ Small & Nicholls 2003.
  3. ^ Roman breakwaters were made with roman concrete
  4. ^ a b "Shoreline Management Guide".
  5. ^ "Australian Coastal Councils Association".
  6. ^ "The Tollesbury and Orplands Managed Retreat Sites". archive.uea.ac.uk. Retrieved 19 February 2017.
  7. ^ MMA 2005, Sitges, Meeting on Coastal Engineering; EUROSION project
  8. ^ Schembri 2009.
  9. ^ "£47.3m project to protect Bournemouth's beaches from erosion over next 100 years".
  10. ^ Armour Units – Random Mass or Disciplined Array, – C.T.Brown ASCE Coastal Structures Specialty Conference, Washington, March 1979; The Design & Construction of Prince St. Seawall, Cronulla, EHW Hirst & D.N.Foster – 8th CCOE, Nov 1987, Launceston, Tasmania
  11. ^ Blackpool South Shore Physical Model Studies, ABP Research Report R 526, December 1985
  12. ^ Mablethorpe to Skegness, Model tests of three design options, P Holmes et al., Imperial College, September 1987
  13. ^ M. N. Bell, P. C. Barber and D. G. E. Smith. The Wallasey Embankment. Proc. Instn Civ. Engrs 1975 (58) pp. 569—590.
  14. ^ [1]
  15. ^ Grant 1946.
  16. ^ Graham, Sault & Bailey 2003.
  17. ^ a b c d e f g h i Boak & Turner 2005.
  18. ^ Woodroffe 2002.
  19. ^ Adapted from Boak & Turner 2005
  20. ^ a b c d e Leatherman 2003.
  21. ^ a b c Pajak & Leatherman 2002.
  22. ^ a b Crowell, Leatherman & Buckley 1991.
  23. ^ a b c Appeaning Addo, Walkden & Mills 2008.
  24. ^ a b c d e f g h Moore 2000.
  25. ^ Anders & Byrnes 1991.
  26. ^ Morton 1991.
  27. ^ Camfield & Morang 1996.
  28. ^ a b Smith & Zarillo 1990.
  29. ^ [2]
  30. ^ Maiti & Bhattacharya 2009.
  31. ^ a b Turner et al. 2004.
  32. ^ Van Koningsveld et al. 2007.
  33. ^ "Argus video monitoring system - Coastal Wiki".
  34. ^ Smit et al. 2007.
  35. ^ Plant, Holland & Haller 2008.
  36. ^ a b Holman, Plant & Holland 2013.
  37. ^ a b Bergsma et al. 2016.
  38. ^ Masselink et al. 2016.
  39. ^ Castelle et al. 2015.

Sources

Further reading

External links

Videos
Images
Accretion (coastal management)

Accretion is the process of coastal sediment returning to the visible portion of a beach or foreshore following a submersion event. A sustainable beach or foreshore often goes through a cycle of submersion during rough weather then accretion during calmer periods. If a coastline is not in a healthy sustainable state, then erosion can be more serious and accretion does not fully restore the original volume of the visible beach or foreshore leading to permanent beach loss.

Apalachicola National Estuarine Research Reserve

The Apalachicola National Estuarine Research Reserve, located in the U.S. State of Florida, protects the biological diversity of the Apalachicola Bay as well as the economic value of the natural resources and pristine conditions.

Between 60 and 85 percent of the local population make their living directly from the fishing industry, most of which is done in reserve waters. Seafood landings from the Apalachicola Reserve are worth $14–16 million dockside annually. At the consumer level, this represents a $900–$800 million industry.

Research projects that target commercial fisheries management and the food chain are a high priority in the Apalachicola Reserve. In addition to its water quality monitoring program, the reserve has engaged in extensive benthic habitat mapping in Apalachicola Bay and has a highly sophisticated geographic information systems (GIS), which is used to educate coastal managers and visiting researchers about the area and its ecology.

Other educational offerings include ongoing guest lectures for the community and coastal management workshops for environmental professionals. The reserve's K-12 educational activities are divided between classroom and on-site programs.

Bangladesh–Netherlands relations

Bangladesh–Netherlands relations refer to the bilateral relations between Bangladesh and Netherlands.

Bird Island, North Carolina

Bird Island is approximately 1,300 acres (5.3 km2) adjacent to the coastal resort town of Sunset Beach, North Carolina, USA. Sunset Beach is on a barrier island and is the southernmost town in North Carolina. Bird Island can be reached by walking along the seashore toward the South Carolina border. Due to the contour of the Atlantic Coast at this point, the direction of travel to Bird Island is approximately West-Southwest. Previously, Bird Island was separated from Sunset Beach by a tidal creek (Mad Inlet) that could be easily crossed only at low tide. Accretion of ocean sand (due to hurricane activity in the 1990s as well as environmental activity to fill in dune grass) has gradually filled in the tidal creek so that two separate islands became one.

Blast fishing

Blast fishing or dynamite fishing is the practice of using explosives to stun or kill schools of fish for easy collection. This often illegal practice can be extremely destructive to the surrounding ecosystem, as the explosion often destroys the underlying habitat (such as coral reefs) that supports the fish. The frequently improvised nature of the explosives used means danger for the fishermen as well, with accidents and injuries.

Breakwater (structure)

Breakwaters are structures constructed near the coasts as part of coastal management or to protect an anchorage from the effects of both weather and longshore drift.

Canterbury Bight

Canterbury Bight is a 135 kilometres (84 mi) stretch of coastline between Dashing Rocks (north Timaru) and the southern side of Banks Peninsula (Birdlings Flat) on the eastern side of the South Island, New Zealand. The bight faces southeast, which exposes it to high-energy storm waves originating in the Pacific Ocean (Kirk, 1967). The most frequent wave approach direction for the Canterbury Bight is from the southeast and the most dominant the south with wave heights of over 2m common (Kirk, 1967). The bight is a large, gently curving bend of shoreline of primarily mixed sand and gravel (MSG) beaches. The MSG beaches are steep, highly reflective (of wave energy) and composed of alluvial gravel deposits. The alluvial gravels are the outwash products of multiple glaciations that occurred in the Southern Alps during the Pleistocene (Kirk, 1967). Large braided rivers transported this material to the edge of the current continental shelf, which, due to sea level rise is 50 km seaward of the coasts current position (Kirk, 1967). The MSG beaches of the Canterbury Bight therefore occur where the alluvial fans of the Canterbury Plains rivers are exposed to high-energy ocean swells (Hart et al., 2008). The dominant rock ‘greywacke’ in the Southern Alps is consequently the primary constituent of the MSG beaches (and Canterbury Plains), which is partially indurated sandstone of the Torlesse Supergroup (Hart et al., 2008). River-mouth lagoons are a relatively common occurrence on the MSG beaches of the Canterbury Bight.

Cliff stabilization

Cliff stabilization is a coastal management erosion control technique. This is most suitable for softer or less stable cliffs. Generally speaking, the cliffs are stabilised through dewatering (drainage of excess rainwater to reduce water-logging) or anchoring (the use of terracing, planting, wiring or concrete supports to hold cliffs in place).

Coastal Zone Management Act

The Coastal Zone Management Act of 1972 (CZMA; Pub.L. 92–583, 86 Stat. 1280, enacted October 27, 1972, 16 U.S.C. §§ 1451–1464, Chapter 33) is an Act of Congress passed in 1972 to encourage coastal states to develop and implement coastal zone management plans (CZMPs). This act was established as a United States National policy to preserve, protect, develop, and where possible, restore or enhance, the resources of the Nation's coastal zone for this and succeeding generations.

Integrated coastal zone management

Integrated coastal zone management (ICZM) or Integrated coastal management (ICM) is a process for the management of the coast using an integrated approach, regarding all aspects of the coastal zone, including geographical and political boundaries, in an attempt to achieve sustainability

This concept was born in 1992 during the Earth Summit of Rio de Janeiro. The specifics regarding ICZM is set out in the proceedings of the summit within Agenda 21, Chapter 17.

The European Commission defines the ICZM as follows:-

ICZM is a dynamic, multidisciplinary and iterative process to promote sustainable management of coastal zones. It covers the full cycle of information collection, planning (in its broadest sense), decision making, management and monitoring of implementation. ICZM uses the informed participation and cooperation of all stakeholders to assess the societal goals in a given coastal area, and to take actions towards meeting these objectives. ICZM seeks, over the long-term, to balance environmental, economic, social, cultural and recreational objectives, all within the limits set by natural dynamics. 'Integrated' in ICZM refers to the integration of objectives and also to the integration of the many instruments needed to meet these objectives. It means integration of all relevant policy areas, sectors, and levels of administration. It means integration of the terrestrial and marine components of the target territory, in both time and space.

To further understand the idea of ICZM several aspects can be defined and further explained. The coastal zone, the concept of sustainability and the term integration all within a coastal management context can be individually defined, while the expectations and framework of ICZM can be further explained. This entry uses the example of the New Zealand national framework to illustrate ICZM.

Jacques Cousteau National Estuarine Research Reserve

The Jacques Cousteau National Estuarine Research Reserve, located in southeastern New Jersey, encompasses over 110,000 acres (450 km²) of terrestrial, wetland and aquatic habitats within the Mullica River-Great Bay Ecosystem.

A wide range of habitats includes the pinelands, lowland swamps, freshwater marshes, salt and freshwater tidal marshes, barrier islands (sandy beaches and dune habitats), shallow bays and the coastal ocean. Little more than one percent of this reserve has been subject to human development. The area is one of the least disturbed estuaries in the densely populated urban corridor of the northeastern United States.

On October 20, 1997 the Jacques Cousteau National Estuarine Research Reserve (JC NERR) was dedicated in honor of Jacques Cousteau. The JC NERR is one of 26 National Estuarine Research Reserve (NERR) created to promote responsible use and management of our nation's estuaries. Estuaries, where the rivers meet the sea, are the wide lower course of a river where its current is met by the tides. This mix of fresh and salt water creates a unique and very productive ecosystem vital to life both on land and in the sea.

The mission of the Jacques Cousteau National Estuarine Research Reserve is to improve management of important estuarine resources in the Mullica River-Great Bay watershed through a program combining scientific research, education, and stewardship. JC NERR conducts research on the physical, chemical and biological components of the site estuaries and neighboring watersheds. The JC NERR offers a variety of professional development programs for teachers highlighting the unique coastal resources of New Jersey for the K-12 classroom. It also offers training programs, resources and outreach materials for New Jersey’s Coastal Management Community. The "Life on the Edge" exhibit housed at the Tuckerton Seaport is a virtual walk from the headwaters of the Mullica River, through the Pinelands, into the marsh ecosystem in Great Bay and then finally out into the open ocean. Visitors learn about the biology, ecology, and importance of estuarine habitats.

Properties within the Reserve are public owned by various state and Federal entities. The Institute of Marine and Coastal Sciences at Rutgers, The State University of New Jersey is the managing partner of JC NERR. Other agency partners include the New Jersey Department of Environmental Protection, The Edwin B. Forsythe National Wildlife Refuge, Stockton University, the Pinelands Commission, The Tuckerton Seaport and The Cooperative Institute of Coastal and Estuarine Environmental Technology.

National Ocean Service

The National Ocean Service (NOS), an office within the U.S. Department of Commerce National Oceanic and Atmospheric Administration (NOAA), is responsible for preserving and enhancing the nation's coastal resources and ecosystems along 95,000 miles (153,000 km) of shoreline bordering 3,500,000 square miles (9,100,000 km2) of coastal, Great Lakes, and ocean waters. Its mission is to "provide science-based solutions through collaborative partnerships to address evolving economic, environmental, and social pressures on our oceans and coasts." NOS works closely with many partner agencies to ensure that ocean and coastal areas are safe, healthy, and productive. National Ocean Service scientists, natural resource managers, and specialists ensure safe and efficient marine transportation, promote innovative solutions to protect coastal communities, and conserve marine and coastal places. NOS is a scientific and technical organization of 1,700 scientists, natural resource managers, and specialists in many different fields. NOS delivers a dynamic range of nationwide coastal and Great Lakes scientific, technical, and resource management services in support of safe, healthy, and productive oceans and coasts. NOS develops partnerships to integrate expertise and efforts across all levels of government and with other interests to protect, maintain, and sustain the viability of coastal communities, economies and ecosystems.

Palm Beach, Queensland

Palm Beach is a coastal suburb on the Gold Coast in Queensland, Australia, between Tallebudgera Creek and Currumbin Creek. At the 2016 Census, Palm Beach had a population of 14,654.

Revetment

In stream restoration, river engineering or coastal engineering, revetments are sloping structures placed on banks or cliffs in such a way as to absorb the energy of incoming water. In military engineering they are structures, again sloped, formed to secure an area from artillery, bombing, or stored explosives. River or coastal revetments are usually built to preserve the existing uses of the shoreline and to protect the slope, as defense against erosion.

Sand dune stabilization

Sand dunes are common features of shoreline and desert environments. Dunes provide habitat for highly specialized plants and animals, including rare and endangered species. They can protect beaches from erosion and recruit sand to eroded beaches. Dunes are threatened by human activity, both intentional and unintentional. Countries such as the United States, Australia, Canada, New Zealand, the United Kingdom, and Netherlands, operate significant dune protection programs.

Stabilizing dunes involves multiple actions. Planting vegetation reduces the impact of wind and water. Wooden sand fences can help retain sand and other material needed for a healthy sand dune ecosystem. Footpaths protect dunes from damage from foot traffic.

They can also protect beaches from erosion and recruit sand to eroded beaches and to many other places too .

The location of the dune limits the types of plant that can thrive there. Beach dunes consist of the foredune, the angled side which faces the ocean, the sand plain at the top of the dune, which may or may not be present, and the backdune, the angled side that faces away from the ocean.

Scalloway

Scalloway (Old Norse: Skálavágr, "bay with the large house(s)") is the largest settlement on the North Atlantic coast of Mainland, the largest island of the Shetland Islands, Scotland. The village had a population of roughly 900, at the 2011 census. Until 1708 it was the capital of the Shetland Islands (now Lerwick, on the east coast of the Shetland Mainland).

Scalloway is the location of the North Atlantic Fisheries College (part of the University of the Highlands and Islands), which offers courses and supports research programmes in fisheries sciences, aquaculture, marine engineering and coastal management. It is also home to the Centre for Nordic Studies. Nearby are the Scalloway Islands, which derive their name from the village.

The village has a swimming pool and a primary school. Scalloway Junior High School, the secondary department was closed in July 2011 by the Shetland Islands Council.

Seagrove Bay

Seagrove Bay is a bay on the northeast coast of the Isle of Wight, England. It lies to the east of the village of Seaview facing towards Selsey Bill with a 2⁄3 mile (1.1 km) shoreline stretching from Nettlestone Point in the north to Horestone Point in the south. The bay has both the Seaside Award Flag and the Water Quality Award.Roughly at the centre is a public slipway, to the north of the slipway is a straight pebble beach and there are many shallow private mooring buoys out in the bay. At the southernmost end of the bay is a wooden walkway which gives access from the end of the seawall to Horestone Point and Priory Bay beyond even during the high tide. The bay previously had public toilets which were demolished in 2015 - with a new block set to be built. Though as of 2018 the construction is stalled due to a land-dispute and portaloos had to be installed at the beach for tourists.The bay is used in the title of the life peer Lord Oakeshott as Baron Oakeshott of Seagrove Bay, of Seagrove in the county of Isle of Wight.

Seawall

A seawall (or sea wall) is a form of coastal defense constructed where the sea, and associated coastal processes, impact directly upon the landforms of the coast. The purpose of a sea wall is to protect areas of human habitation, conservation and leisure activities from the action of tides, waves, or tsunamis. As a seawall is a static feature it will conflict with the dynamic nature of the coast and impede the exchange of sediment between land and sea. The shoreline is part of the coastal interface which is exposed to a wide range of erosional processes arising from fluvial, aeolian and terrestrial sources, meaning that a combination of denudational processes will work against a seawall.The coast is generally a high-energy, dynamic environment with spatial variations over a wide range of timescales. The coast is exposed to erosion by rivers and winds as well as the sea, so that a combination of denudational processes will work against a sea wall.

Because of these persistent natural forces, sea walls need to be maintained (and eventually replaced) to maintain their effectiveness.

The many types of sea wall in use today reflect both the varying physical forces they are designed to withstand, and location specific aspects, such as local climate, coastal position, wave regime, and value of landform. Sea walls are hard engineering shore-based structures which protect the coast from erosion. But various environmental problems and issues may arise from the construction of a sea wall, including disrupting sediment movement and transport patterns. Combined with a high construction cost, this has led to an increasing use of other soft engineering coastal management options such as beach replenishment.

Sea walls may be constructed from various materials, most commonly reinforced concrete, boulders, steel, or gabions. Other possible construction materials are: vinyl, wood, aluminium, fibreglass composite, and large biodegrable sandbags made of jute and coir. In the UK, sea wall also refers to an earthen bank used to create a polder, or a dike construction.

Submersion (coastal management)

Submersion is the sustainable cyclic portion of coastal erosion where coastal sediments move from the visible portion of a beach to the submerged nearshore region, and later return to the original visible portion of the beach. The recovery portion of the sustainable cycle of sediment behaviour is (accretion).

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