Editing Polder

{{short description|Reclaimed land}}
{{Other uses}}
[[File:Flevopolder Larserbos.jpg|thumb|Aerial view of [[Flevopolder]], the [[Netherlands]]]]
[[File:Noordoostpolder by Sentinel-2, 2018-06-30.jpg|alt=|thumb|[[Satellite imagery|Satellite image]] of [[Noordoostpolder]], the Netherlands (595.41&nbsp;km<sup>2</sup>)]]
A '''polder''' ({{IPA|nl|ˈpɔldər|-|Nl-polder.ogg}})  is a low-lying tract of land that forms an artificial [[hydrology|hydrological]] entity, enclosed by embankments known as [[levee|dikes]]. The three types of polder are:

# [[Land reclamation|Land reclaimed]] from a body of water, such as a lake or the [[seabed]]
# [[Floodplain|Flood plains]] separated from the sea or river by a dike
# [[Marsh]]es separated from the surrounding water by a dike and subsequently drained; these are also known as ''[[koog]]s'', especially in Germany

The ground level in drained marshes [[subsidence|subsides]] over time. All polders will eventually be below the surrounding water level some or all of the time. Water enters the low-lying polder through [[infiltration (hydrology)|infiltration]] and water pressure of [[groundwater]], or rainfall, or transport of water by rivers and canals. This usually means that the polder has an excess of water, which is pumped out or drained by opening [[sluice]]s at [[low tide]]. Care must be taken not to set the internal water level too low. Polder land made up of [[peat]] (former marshland) will sink in relation to its previous level, because of peat decomposing when exposed to oxygen from the air. 
 
Polders are at risk of flooding at all times, and care must be taken to protect the surrounding dikes. Dikes are typically built with locally available materials, and each material has its own risks: sand is prone to collapse owing to saturation by water; dry peat is lighter than water and potentially unable to retain water in very dry seasons. Some animals dig tunnels in the barrier, allowing water to infiltrate the structure; the [[muskrat]] is known for this activity and hunted in certain European countries because of it. Polders are most commonly, though not exclusively, found in river deltas, former [[fen]]lands, and coastal areas.

Flooding of polders has also been used as a military tactic in the past. One example is the flooding of the polders along the [[Yser]] River during [[World War I]]. Opening the sluices at high tide and closing them at low tide turned the polders into an inaccessible swamp, which allowed the [[Battle of the Yser#Battle|Allied armies to stop the German army]].

The [[Netherlands]] has a large area of polders: as much as 20% of the land area has at some point in the past been reclaimed from the sea, thus contributing to the development of the country. [[IJsselmeer]] is the most famous polder project of the Netherlands. Some other countries which have polders are [[Bangladesh]], [[Belgium]], [[Canada]] and [[China]]. Some examples of Dutch polder projects are [[Beemster]], [[Schermer]], [[Flevopolder]] and [[Noordoostpolder]].

==Etymology==
The [[Dutch language|Dutch]] word {{lang|nl|polder}} derives successively from [[Middle Dutch]] {{lang|dum|polre}}, from [[Old Dutch]] {{lang|odt|polra}}, and ultimately from ''pol-'', a piece of land elevated above its surroundings, with the [[augmentative]] suffix ''-er'' and [[Epenthesis|epenthetical]] '' -d-''. The word has been adopted in thirty-six languages.<ref>Sijs, N. van der, 2010. Nederlandse woorden wereldwijd, 747 pp. Sdu Uitgevers bv, Den Haag. {{ISBN|9789012582148}}, https://pure.knaw.nl/portal/files/458170/Nww_compleet_archief.pdf, page 155</ref>

==Netherlands==
{{anchor|Polders and the Netherlands}}
{{More citations needed|section|date=July 2021}}
[[File:Gemaal de Leyens.jpg|200px|thumb|right|Pumping station in [[Zoetermeer]], [[Netherlands]]: The polder lies lower than the surrounding water on the other side of the dike. The [[Archimedes' screw]]s are clearly visible.]]

The [[Netherlands]] is frequently associated with polders, as its engineers became noted for developing techniques to drain wetlands and make them usable for agriculture and other development. This is illustrated by the saying "God created the world, but the Dutch created the Netherlands".<ref>Cf. Forrest Clingerman, Brian Treanor, Martin Drenthen, David Utsler, ''Interpreting Nature: The Emerging Field of Environmental Hermeneutics'', Fordham University Press, 1 sep. 2013. The sentence stems from a poem by Archibald Pitcairn (1652–1713): ''Tellurem fecere dei, sua littora Belgae''. C.D. van Strien, ''British Travellers in Holland During the Stuart Period: Edward Browne and John Locke as Tourists in the United Provinces'', Leiden 1993, 164.</ref>

The [[Dutch people|Dutch]] have a long history of reclamation of marshes and fenland, resulting in some 3,000 ''polders''<ref>{{cite web| url=https://www.rijkswaterstaat.nl/rws/waterinnovatiebron/cgi-bin/toonlijst.pl?config=config&var=volgnr&val=1&layout=index-forceframe&confignr=1&menu=1067260347&menuitem=1120115781| publisher=Rijkswaterstaat| title=''Kijk naar de geschiedenis''| access-date=2008-01-21}}{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> nationwide. By 1961, about half of the country's land, {{convert|6800|sqmi|order=flip||}}, was reclaimed from the sea.<ref name="ley196110">{{Cite magazine
 |last=Ley
 |first=Willy
 |date=October 1961
 |title=The Home-Made Land
 |department=For Your Information
 |url=https://archive.org/stream/Galaxy_v19n06_1961-08#page/n65/mode/1up
 |magazine=Galaxy Science Fiction
 |pages=92–106
}}</ref>{{Better source|date=July 2021}} About half the total surface area of ''polders'' in northwest Europe is in the Netherlands. The first [[embankment dam|embankments]] in Europe were constructed in Roman times. The first polders were constructed in the 11th century. The oldest extant polder is the [[Achtermeer]] polder, from 1533.

As a result of flooding disasters, [[Water board (The Netherlands)|water board]]s called ''waterschap'' (when situated more inland) or ''hoogheemraadschap'' (near the sea, mainly used in the [[Holland]] region)<ref>{{cite web| title=waterschap|url = http://www.waterschappen.nl/mijn-waterschap.html| archive-url=https://web.archive.org/web/20121102142234/http://www.waterschappen.nl/|archive-date=2012-11-02}}</ref><ref>Reh, W., Steenbergen, C., Aten, D. 2007. Sea of Land, The polder as an experimental atlas of Dutch landscape architecture. 344 pp, Uitgeverij Architectura & Natura. {{ISBN|9789071123962}}</ref> were set up to maintain the integrity of the water defences around polders, maintain the waterways inside a polder, and control the various water levels inside and outside the polder. Water boards hold separate elections, levy taxes, and function independently from other government bodies. Their function is basically unchanged even today. As such, they are the oldest democratic institutions in the country. The necessary cooperation among all ranks to maintain polder integrity gave its name to the Dutch version of [[Third Way (centrism)|third-way politics]]—the ''[[Polder Model]]''.

The [[North Sea flood of 1953|1953 flood disaster]] prompted a new approach to the design of dikes and other water-retaining structures, based on an acceptable probability of overflowing. Risk is defined as the product of probability and consequences. The potential damage in lives, property, and rebuilding costs is compared with the potential cost of water defences. From these calculations follows an acceptable flood risk from the sea at one in 4,000–10,000&nbsp;years, while it is one in 100–2,500&nbsp;years for a river flood. The particular established policy guides the Dutch government to improve flood defences as new data on threat levels become available.

Major Dutch polders and the years they were laid dry include [[Beemster]] (1609–1612), [[Schermer]] (1633–1635), and [[Haarlemmermeerpolder]] (1852). Polders created as part of the [[Zuiderzee Works]] include [[Wieringermeerpolder]] (1930), [[Noordoostpolder]] (1942) and [[Flevopolder]] (1956–1968)

== Examples of polders ==
{{More citations needed|section|date=July 2021}}

===Brazil===
Several cities on the [[Paraíba Valley]] region (in the state of [[São Paulo (state)|São Paulo]]) have polders on land claimed from the floodplains around the [[Paraíba do Sul]] river.

===Bangladesh===
[[Bangladesh]] has 139 polders, of which 49 are sea-facing, while the rest are along the numerous [[Distributary|distributaries]] of the Ganges-Brahmaputra-Meghna River delta. These were constructed in the 1960s to protect the coast from tidal flooding and reduce salinity incursion.<ref>[http://www.irinnews.org/report/98292/bangladesh-polders-under-threat "Bangladesh polders under threat"], Irin News</ref> They reduce long-term flooding and waterlogging following [[storm surge]]s from [[tropical cyclone]]s. They are also cultivated for agriculture.<ref>[http://unearthnews.org/2013/07/17/bangladeshi-project-to-enhance-polders-amidst-climate-woes/ "Bangladeshi project to enhance polders amidst climate woes"] {{webarchive|url=https://web.archive.org/web/20140408091108/http://unearthnews.org/2013/07/17/bangladeshi-project-to-enhance-polders-amidst-climate-woes/ |date=2014-04-08 }}, Unearth News</ref>

===Belgium===
[[File:Diksmuide - Polders - IJzer.jpg|thumb|The [[Yser]] river and West Flemish polders near [[Diksmuide]]]]
* De Moeren, near [[Veurne]] in [[West Flanders]]
* Polders along the [[Yser]] river between [[Nieuwpoort, Belgium|Nieuwpoort]] and [[Diksmuide]]
* Polders of Muisbroek and Ettenhoven, in [[Ekeren]] and [[Hoevenen]]
* Polder of Stabroek, in [[Stabroek]]
* Kabeljauwpolder, in [[Zandvliet]]
* Scheldepolders on the left bank of [[Scheldt|the Scheldt]]
* Uitkerkse polders, near Blankenberge in West Flanders
* Prosperpolder, near Doel, Antwerp and Kieldrecht.

===Canada===
* [[Tantramar Marshes]]
* [[Holland Marsh]]
* [[Pitt Polder Ecological Reserve]]
* [[Grand Pré, Nova Scotia]]
* [[Minas Basin]]

=== China ===

* The city of [[Kunshan]] has over 100 polders.<ref>{{Cite web|url=https://watersensitivecities.org.au/wp-content/uploads/2016/12/CRCWSC_TradeMissiontoKunshan_R2.pdf |archive-url=https://web.archive.org/web/20170409122536/https://watersensitivecities.org.au/wp-content/uploads/2016/12/CRCWSC_TradeMissiontoKunshan_R2.pdf |archive-date=2017-04-09 |url-status=live|title=CRCWSC Trade Mission to Kunshan|date=2016-12-01}}</ref>

====History====
The [[Jiangnan]] region, at the [[Yangtze River Delta]], has a long history of constructing polders. Most of these projects were performed between the 10th and 13th centuries.<ref>{{cite book |last1=Liao, Qiyu 繆启愉 |title=Taihu Tangpu Weitian Shi Yanjiu 太湖塘浦圩田史研究 [The research of the dikes and polders of Lake Tai] |date=1985 |publisher=Nongye Chubanshe |location=Beijing}}</ref> The Chinese government also assisted local communities in constructing dikes for swampland water drainage.<ref>{{cite journal |last1=Xie, Shi 谢湜 |title="11 Shiji Taihu Diqu Nongtian Shuili Geju de Xingcheng" 11 世纪太湖地区农田水利格局的形成 [The formation of water management system in the farmland of the Lake Tai region in the eleventh century] |journal=Journal of Sun Yat-sen University |date=2010 |volume=50 |issue=5 |pages=94–106}}</ref> The Lijia (里甲) self-monitoring system  of 110 households under a ''lizhang'' (里长) headman was used for the purposes of service administration and tax collection in the polder, with a ''liangzhang'' (粮长, grain chief) responsible for maintaining the water system and a ''tangzhang'' (塘长, dike chief) for polder maintenance.<ref>{{cite book |last1=Hamashima, Atsutoshi 滨岛敦俊 |title=Mindai Kōnan nōson shakai no kenkyū 明代江南農村社会の研究 [Rural Society in Jiangnan during the Ming Dynasty |date=1982 |publisher=Tokyo University Press |location=Tokyo |pages=9–65}}</ref>

===Denmark===
* Filsø
* [[Kolindsund]]
* [[Lammefjorden]]

===Finland===
* [[Söderfjärden]]
* [[Munsmo]]
* Two polders ({{convert|3|km2|disp=or|spell=in|}} in total) near [[Vassor]] in [[Korsholm]]

===France===
* [[Marais Poitevin]]
* [[Les Moëres]], adjacent to the Flemish polder ''De Moeren'' in Belgium.
* Polders de Couesnon near [[Mont-Saint-Michel|Mont-Saint Michel]] in Normandy<ref>{{Cite web |title=les polders |url=https://littoral-normand.n2000.fr/sites/littoral-normand.n2000.fr/files/documents/page/les_polders.pdf |access-date=2023-03-25 |website=littoral-normand.n2000.fr}}</ref>

===Germany===
{{main|Koog}}
[[File:Seehundstation Schleuse.JPG|thumb|[[Friedrichskoog]] is a polder in Schleswig-Holstein]]
[[File:Luftaufnahmen Nordseekueste 2012-05-by-RaBoe-355.jpg|thumb|[[Wesselburenerkoog]]]]
In Germany, land reclaimed by diking is called a ''koog''. The German ''Deichgraf'' system was similar to the Dutch and is widely known from [[Theodor Storm]]'s novella ''[[The Rider on the White Horse]]''.

* Altes Land near Hamburg
* [[Blockland, Bremen|Blockland]] and Hollerland near Bremen
* [[Nordstrand, Germany]]
* Bormerkoog and Meggerkoog near [[Friedrichstadt]]
* 36 ''koogs'' in the district of [[Nordfriesland]]
* 12 ''koogs'' in the district of [[Dithmarschen]]

In southern Germany, the term ''polder'' is used for [[retention basin]]s recreated by opening dikes during river [[floodplain restoration]], a meaning somewhat opposite to that in coastal context.

===Guyana===
* Black Bush Polder, Corentyne, Berbice.

===India===
* [[Kuttanad]] Region, [[Kerala]]<ref name="Kuttanad">{{Cite journal | title = Rain continues to throw a challenge in Kuttanad | journal = The Hindu  | publisher = The Hindu Group  | year = 2011 | url = http://www.thehindu.com/todays-paper/tp-national/tp-kerala/article1765439.ece?css=print | access-date = 2011-06-10}}</ref><ref name="Kuttanad2">{{Cite journal | last = Thampatti | first = Manorama | title = Rice Bowl in Turmoil: The Kuttanad Wetland Ecosystem | journal = Resonance | publisher = Indian Academy of Sciences | date = March 1999 | url = https://www.scribd.com/doc/17029034/Degrading-wetland-backwater-ecosystem-of-Kuttanad-India | access-date = 2011-06-10 | url-status = dead | archive-url = https://web.archive.org/web/20101216032932/http://www.scribd.com/doc/17029034/Degrading-wetland-backwater-ecosystem-of-Kuttanad-India | archive-date = 2010-12-16 }}</ref>

===Ireland===
* [[Lough Swilly]], [[County Donegal]]. Near [[Inch Island]] and [[Newtowncunningham]].<ref>{{cite web|title=Inch Wildfowl Reserve History|url=http://www.inchandfoyle.com/history|website=Inch and Foyle Wildfowl Project|access-date=5 June 2015|archive-url=https://web.archive.org/web/20150907033355/http://www.inchandfoyle.com/history|archive-date=7 September 2015|url-status=dead|df=dmy-all}}</ref>

===Italy===
* Delta of the river [[Po River|Po]], such as Bonifica Valle del Mezzano

=== Japan ===

* Around the [[Ariake Sea]] in Kyushu, mainly in [[Saga Prefecture|Saga]] but also in [[Fukuoka Prefecture|Fukuoka]] and [[Kumamoto Prefecture|Kumamoto]] Prefectures

===Lithuania===
* [[Rusnė Island]]

===Netherlands===
[[File:Netherlands, Kaag en Braassem, Stingsloot.JPG|thumb|The meandering Stingsloot separates the Vrouw Vennepolder (left) and the Rode Polder (right)]]
[[File:WW17-133 (33128552163).jpg|thumb|Wind farms in the [[Noordoostpolder]]]]
[[File:The Netherlands below sealevel and protected from floods.png|thumb|right|Areas of the Netherlands located below sea level (blue)]]
* [[Achtermeer]], the oldest polder, from 1533
* [[Alblasserwaard]], containing the windmills of [[Kinderdijk]], a [[World Heritage Site]]
* [[Alkmaar]]
* [[Andijk]]
* [[Anna Paulownapolder]]
* [[Beemster]], a World Heritage Site
* [[Bijlmermeer]]
* [[Flevopolder]], the largest [[artificial island]] in the world, last part drained in 1968
* [['s-Gravesloot]]
* [[Haarlemmermeer]], containing [[Schiphol]] airport
* [[Krimpenerwaard]]
* [[Lauwersmeer]]
* [[Mastenbroek]], one of the oldest medieval polders, drained around 1363-1364.<ref>{{cite web | url=https://www.canonvannederland.nl/nl/overijssel/salland/zwartewaterland/-mastenbroekerpolder | title=De Mastenbroekerpolder }}</ref><ref>{{cite web | url=https://www.staatsbosbeheer.nl/uit-in-de-natuur/locaties/polder-mastenbroek | title=Polder Mastenbroek }}</ref>
* [[Noordoostpolder]]
* [[Prins Alexander]]polder
* [[Purmer]]
* [[Schermer]]
* [[Watergraafsmeer]]
* [[Wieringermeer]]
* [[Wieringerwaard]]
* [[Wijdewormer]]
* Zestienhoven, home of the [[Rotterdam The Hague Airport]] ([[Overschie]]), in the city of [[Rotterdam]].
* [[Zuidplaspolder]], along with [[Lammefjord]] in Denmark the lowest point of the European Union

===Poland===
* [[Vistula]] delta near [[Elbląg]] and [[Nowy Dwór Gdański]]
* [[Warta]] delta near [[Kostrzyn nad Odrą]]

===Romania===
* [[Danube Delta]]

===Singapore===
* Parts of [[Pulau Tekong]]

===Slovenia===
* The [[Ankaran|Ankaran/Ancarano]] Polder ({{langx|sl|Ankaranska bonifika}}), [[Semedela]] Polder ({{lang|sl|Semedelska bonifika}}), and Škocjan Polder ({{lang|sl|Škocjanska bonifika}}) in reclaimed land around [[Koper|Koper/Capodistria]].

===South Korea===
* Parts of the coast of [[Ganghwa Island]], adjacent to the river [[Han River (Korea)|Han]] in [[Incheon]]
* Delta of the river [[Nakdong River|Nakdong]] in [[Busan]]
* [[Saemangeum]] in [[North Jeolla Province]]

===Spain===
* Parts of [[Málaga]] were built on reclaimed land

===United Kingdom===
* [[Traeth Mawr]]
* [[Sunk Island]], on the north shore of the [[Humber]] east of [[Kingston upon Hull|Hull]]
*[[Caldicot and Wentloog Levels]] along the [[Severn Estuary]] in South Wales
* Parts of [[The Fens]]
**[[Branston, Lincolnshire|Branston Island]], by the [[River Witham]] outside the conventional area of the fens but connected to them.
* Parts of the coast of [[Essex]]
* Some land along the [[River Plym]] in [[Plymouth]]
* Some land around [[Meathop]] east of [[Grange-over-Sands]], reclaimed as a side-effect of building a [[railway]] [[Embankment (transportation)|embankment]]
* The [[Somerset Levels]] and [[North Somerset Levels]]
* [[Romney Marsh]]
* [[Sealand, Flintshire]]
* [[Humberhead Levels]]

===United States===
* [[New Orleans]]
* [[Sacramento – San Joaquin River Delta]]

== See also ==
*[[Afsluitdijk]]
*[[Flood control in the Netherlands]]
*[[Land reclamation]]
*[[Windpump]]

==References==
<references />

==Further reading==
* Derex, Jean-Michel, Franco Cazzola (eds.) 2004. 2nd ed. 2013. ''Eau et développement dans l'Europe moderne''. Paris, Maison des Sciences De L'Homme
* Farjon, J.M.J., J. Dirkx, A. Koomen, J. Vervloet & W. Lammers. 2001. ''Neder-landschap Internationaal: bouwstenen voor een selectie van gebieden landschapsbehoud.'' Alterra, Wageningen. [http://www2.alterra.wur.nl/Webdocs/PDFFiles/Alterrarapporten/AlterraRapport358.pdf Rapport 358] {{Webarchive|url=https://web.archive.org/web/20121028204957/http://www2.alterra.wur.nl/Webdocs/PDFFiles/Alterrarapporten/AlterraRapport358.pdf |date=2012-10-28 }}.
* Stenak, Morten. 2005. ''De inddæmmede Landskaber – En historisk geografi.'' Landbohistorik Selskab.
* ''[http://edepot.wur.nl/380818 Polders of the World. Keynotes International Symposium]''. 1982. Lelystad, The Netherlands
* Ven, G.P. van de (ed.) 1993, 4th ed. 2004. ''Man-made Lowlands. History of Water Management and Land Reclamation in the Netherlands'', Matrijs, Utrecht.
* Wagret, Paul. 1972. ''Polderlands.'' London: Methuen.

==External links==
{{commons category|Polders}}
* [http://home.planet.nl/~farjo001/internat_uk.htm Polder landscapes in the Netherlands] – ''in a northwest European and a landmark context''.
* [http://static.nai.nl/polders/e/hoe_e.html How to make a polder – online film] {{Webarchive|url=https://web.archive.org/web/20210417072114/https://static.nai.nl/polders/e/hoe_e.html |date=2021-04-17 }}
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[[Category:Polders| ]]
[[Category:Artificial landforms]]
[[Category:Land reclamation]]
[[Category:Environmental soil science]]
[[Category:Riparian zone]]
[[Category:Coastal construction]]
[[Category:Freshwater ecology]]