A coastline or a seashore is the area where land meets the sea or ocean, or a line that forms the boundary between the land and the ocean or a lake. A precise line that can be called a coastline cannot be determined due to the Coastline paradox. The term coastal zone is a region where interaction of the sea and land processes occurs. Both the terms coast and coastal are often used to describe a geographic location or region; for example, New Zealand's West Coast, or the East and West Coasts of the United States. Edinburgh for example is a city on the coast of Scotland. A pelagic coast refers to a coast which fronts the open ocean, as opposed to a more sheltered coast in a gulf or bay. A shore, on the other hand, can refer to parts of land adjoining any large body of water, including oceans (sea shore) and lakes (lake shore). Similarly, the somewhat related term "[stream bed/bank]" refers to the land alongside or sloping down to a river (riverbank) or body of water smaller than a lake. "Bank" is also used in some parts of the world to refer to an artificial ridge of earth intended to retain the water of a river or pond; in other places this may be called a levee. While many scientific experts might agree on a common definition of the term "coast", the delineation of the extents of a coast differ according to jurisdiction, with many scientific and government authorities in various countries differing for economic and social policy reasons. According to the UN atlas, 44% of people live within 150 kilometres (93 miles) of the sea.
1 Formation 2 Environmental importance 3 Human impacts
3.1 Human uses of coasts 3.2 Threats to a coast 3.3 Conservation
4 Types of coast 5 Coastal landforms
6 Coastal processes 7 Wildlife
7.1 Animals 7.2 Plants
8 Coastline statistics
8.1 Coastline problem 8.2 Measuring a coastline
9 See also 10 Notes 11 References 12 External links
Atlantic rocky coastline, showing a surf area. Porto Covo, west coast of Portugal
Tides often determine the range over which sediment is deposited or
eroded. Areas with high tidal ranges allow waves to reach farther up
the shore, and areas with lower tidal ranges produce deprossosition at
a smaller elevation interval. The tidal range is influenced by the
size and shape of the coastline. Tides do not typically cause erosion
by themselves; however, tidal bores can erode as the waves surge up
river estuaries from the ocean.
Waves erode coastline as they break on shore releasing their energy;
the larger the wave the more energy it releases and the more sediment
it moves. Coastlines with longer shores have more room for the waves
to disperse their energy, while coasts with cliffs and short shore
faces give little room for the wave energy to be dispersed. In these
areas the wave energy breaking against the cliffs is higher, and air
and water are compressed into cracks in the rock, forcing the rock
apart, breaking it down.
The coast and its adjacent areas on and off shore are an important part of a local ecosystem: the mixture of fresh water and salt water (brackish water) in estuaries provides many nutrients for marine life. Salt marshes and beaches also support a diversity of plants, animals and insects crucial to the food chain. The high level of biodiversity creates a high level of biological activity, which has attracted human activity for thousands of years. Human impacts Human uses of coasts
The Coastal Hazard Wheel system published by UNEP for global coastal management
A settled coastline in Marblehead, Massachusetts. Once a fishing port, the harbor is now dedicated to tourism and pleasure boating. Observe that the sand and rocks have been darkened by oil slick up to the high-water line.
This stretch of coast in Tanzania's capital Dar es Salaam serves as a public waste dump.
Houses close to the coast, like these in Tiburon, California, may be especially desirable properties.
View of sea coast from top of a hill at
More and more of the world's people live in coastal regions. Many
major cities are on or near good harbors and have port facilities.
Some landlocked places have achieved port status by building canals.
The coast is a frontier that nations have typically defended against
military invaders, smugglers and illegal migrants. Fixed coastal
defenses have long been erected in many nations and coastal countries
typically have a navy and some form of coast guard.
Coasts, especially those with beaches and warm water, attract
tourists. In many island nations such as those of the Mediterranean,
South Pacific and Caribbean, tourism is central to the economy. Coasts
offer recreational activities such as swimming, fishing, surfing,
boating, and sunbathing.
Growth management can be a challenge for
coastal local authorities who often struggle to provide the
infrastructure required by new residents.
Threats to a coast
Coasts also face many human-induced environmental impacts. The human
influence on climate change is thought to contribute to an accelerated
trend in sea level rise which threatens coastal habitats.
Pollution can occur from a number of sources: garbage and industrial
debris; the transportation of petroleum in tankers, increasing the
probability of large oil spills; small oil spills created by large and
small vessels, which flush bilge water into the ocean.
A cliffed coast or abrasion coast is one where marine action has produced steep declivities known as cliffs. A flat coast is one where the land gradually descends into the sea. A graded shoreline is one where wind and water action has produced a flat and straight coastline.
Coastal landforms. The feature shown here as a bay would, in certain (mainly southern) parts of Britain, be called a cove. That between the cuspate foreland and the tombolo is a British bay.
The following articles describe some coastal landforms
Bay Headland Cove Peninsula
Much of the sediment deposited along a coast is the result of erosion
of a surrounding cliff, or bluff.
Coastal features formed by sediment
Coastal features formed by another feature
Lagoon Salt marsh
Other features on the coast
Coastal processes The following articles describe the various geologic processes that affect a coastal zone:
Sedimentation Coastal sediment supply
sediment transport solution subaerial processes suspension
Tides Water waves
diffraction refraction wave breaking wave shoaling
I coined fractal from the
A key property of the fractal is self-similarity; that is, at any scale the same general configuration appears. A coastline is perceived as bays alternating with promontories. In the hypothetical situation that a given coastline has this property of self-similarity, then no matter how greatly any one small section of coastline is magnified, a similar pattern of smaller bays and promontories superimposed on larger bays and promontories appears, right down to the grains of sand. At that scale the coastline appears as a momentarily shifting, potentially infinitely long thread with a stochastic arrangement of bays and promontories formed from the small objects at hand. In such an environment (as opposed to smooth curves) Mandelbrot asserts "coastline length turns out to be an elusive notion that slips between the fingers of those who want to grasp it." There are different kinds of fractals. A coastline with the stated property is in "a first category of fractals, namely curves whose fractal dimension is greater than 1." That last statement represents an extension by Mandelbrot of Richardson's thought. Mandelbrot's statement of the Richardson Effect is:
L ( ϵ ) ∼ F
1 − D
displaystyle L(epsilon )sim Fepsilon ^ 1-D ,
where L, coastline length, a function of the measurement unit, ε, is approximated by the expression. F is a constant and D is a parameter that Richardson found depended on the coastline approximated by L. He gave no theoretical explanation but Mandelbrot identified D with a non-integer form of the Hausdorff dimension, later the fractal dimension. Rearranging the right side of the expression obtains:
displaystyle frac F epsilon ^ D cdot epsilon
where Fε−D must be the number of units ε required to obtain L. The
fractal dimension is the number of the dimensions of the figure being
used to approximate the fractal: 0 for a dot, 1 for a line, 2 for a
square. D in the expression is between 1 and 2, for coastlines
typically less than 1.5. The broken line measuring the coast does not
extend in one direction nor does it represent an area, but is
intermediate. It can be interpreted as a thick line or band of width
2ε. More broken coastlines have greater D and therefore L is longer
for the same ε. Mandelbrot showed that D is independent of ε.
Further information: How Long Is the
Coastal and Estuarine Research Federation
Coastal development hazards
Coastline of the North Sea
European Atlas of the Seas
How Long Is the
^ "Coast". The American Heritage Dictionary of the English Language: Fourth Edition. 2000. Archived from the original on 2009-02-01. Retrieved 2008-12-11. ^ The Merriam-Webster Dictionary Internet edition. Retrieved 2015-06-13. ^ Nelson, Stephen A. (2007). "Coastal Zones". Retrieved 2008-12-11. ^ "UN Atlas". Archived from the original on 2 November 2013. Retrieved 31 October 2013. ^ Davidson (2002), p.421. ^ a b c Easterbrook (1999). ^ Goudarzi, Sara (July 18, 2006). "Flocking to the Coast: World's Population Migrating into Danger". Live Science. Retrieved 2008-12-14. ^ Ashford, Oliver M.; Charnock, H.; Drazin, P. G.; et al., eds. (1993). "The Collected Papers of Lewis Fry Richardson:". 1, Meteorology and numerical analysis. Cambridge University Press (CUP) Archive: 45–46. ISBN 0-521-38297-1. contribution= ignored (help). ^ a b Mandelbrot (1983) page 28. ^ Mandelbrot (1983), page 1. ^ Mandelbrot (1983), pages 29–31.
Burke, Lauretta A.; Kura, Yumiko; Kassem, Ken; Revenga, Carmen;
Spalding, Mark; McAllister, Don (2001). Hutter, Carolynne, ed. "Pilot
Analysis of Global Ecosystems". World Resources Institute.
ISBN 978-1-56973-458-2. contribution= ignored (help)
Davidson, Jon P.; Reed, Walter E.; Davis, Paul M. (2002). Exploring
Earth: An Introduction to Physical Geology. Upper Saddle River, NJ:
Prentice-Hall Inc. ISBN 978-0-13-018372-9.
Easterbrook, Don J. (1999). Surface Processes and Landforms (2 ed.).
Upper Saddle River, NJ: Prentice-Hall Inc.
Haslett, Simon K. (2009). Coastal Systems (2nd Edition). introduction
to environment. New York: Routledge.
Mandelbrot, Benoit B. "II.5 How long is the coast of Britain?". The
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v t e
Headlands and bays
Large-scale coastal behaviour
Accretion Coastal management Integrated coastal zone management Submersion
Bulkhead line Grain size
boulder clay cobble granule pebble sand shingle silt
Intertidal zone Littoral zone Physical oceanography Region of freshwater influence