Satellite image of Noordoostpolder, Netherlands (595.41 km²)

A polder is a low-lying tract of land enclosed by embankments known as dikes, that forms an artificial hydrological entity, meaning it has no connection with outside water other than through man operated devices. There are three types of polders: This article is about the geographical feature. ... Image File history File links Download high resolution version (1024x702, 1423 KB) Satellite image of the Noordoostpolder, part of the Flevopolder. ... Image File history File links Download high resolution version (1024x702, 1423 KB) Satellite image of the Noordoostpolder, part of the Flevopolder. ... Afsluitdijk, a 32 km dike in the Netherlands. ... Water covers 70% of the Earths surface. ...

• land reclaimed from a body of water, such as a lake or the sea bed;
• Flood plains separated from the sea or river by a dyke;
• Marshes separated from the surrounding water by a dyke and consequentially drained.

The ground level in drained marshes subsides over time and thus all polders will eventually be below the surrounding water level some or all of the time. Water enters the low-lying polder through: ground swell due to water pressure on ground water, rain fall and transportation of water by rivers and canals. This usually means that the polder has an excess of water that needs to be pumped out or drained by opening sluices at low tide. However care must be taken in not setting the internal water level too low. Polder land made up of peat (former marshland) will show accelerated compression due to the peat decomposing in dry conditions. Land reclamation is either of two distinct practices. ... For other uses, see Lake (disambiguation). ... This article is about the body of water. ... It has been suggested that this article or section be merged with Floodplain. ... This article is about marsh, a type of wetland. ... Sluice gates near Henley, on the River Thames A small wooden sluice in Magome, Japan, used to power a waterwheel. ... This article is about tides in the ocean. ... Peat in Lewis, Scotland Peat is an accumulation of partially decayed vegetation matter. ...

Polder are at risk from flooding at all times and care must be taken to protect the dykes surrounding a polder. Dykes are mostly build using locally available materials and each has its own risk factor: sand is prone to collapse due to oversaturation by water; dry peat is lighter than water, making the barrier potentially unstable in very dry seasons. Some animals dig tunnels in the barrier, undermining the structure; the muskrat is notorious for this behavior. For this reason in the Netherlands it is actively hunted to extinction. No such care is taken in neighboring Germany though, causing the stock to be constantly resupplied across the border. Binomial name (Linnaeus, 1766) Muskrat range (native range in red, introduced range in green) Muskrat Tucker hole, middle Patuxent River marsh, Maryland The Muskrat or Musquash (Ondatra zibethicus), the only species in genus Ondatra, is a large aquatic rodent native to North America, and introduced in parts of Europe. ...

Polders are most commonly found, though not exclusively so, in river deltas, former fen lands and coastal areas. A fen is a sere, a phase in the natural ecological succession from the open water of a lake to (for example) woodland. ...

Polders and the Netherlands

Windmill in North-Holland, the polder lies lower than the surrounding water on the other side of the dyke

The Netherlands is frequently associated with polders. This is illustrated by the English saying: God created the world, but the Dutch created Holland.

The Dutch have a long history of reclamation of marshes and fenland, resulting in some 3,000 polders ^[1] nationwide. About half of all polder surface within northwest Europe is located within the Netherlands. The first embankments in Europe were constructed in Roman times. The first polders were constructed in the 11th century. Due to flooding disasters water boards called waterschap (below sealevel) or hoogheemraadschap (above sea level) were set up to maintain the integrity of the water defenses around polders, maintain the waterways inside a polder and control the various water levels inside and outside the polder. Water bodies hold separate elections, levy taxes and function independently from other government bodies. Their function is basically unchanged through this day. As such they are the oldest democratic institution in the country. The necessary co-operation between all ranks in maintaining polder integrity also gave its name to the Dutch version of third way politics - the Polder Model. A water board (Dutch: waterschap or hoogheemraadschap, Flanders and Northern France: watringue, France: agence de leau, German: Wasserverband) is a regional organisation charged with the supply of water and care of water levels in its area. ... Bill Clinton and Tony Blair, adherents of the Third Way The Third Way, or Radical center, is a centrist political philosophy of governance that embraces a mix of market and interventionist philosophies. ... The polder model is the Dutch version of corporatism. ...

The 1953 flood disaster prompted a new approach to the design of dikes and other water retaining structures, it is based on an acceptable probability of overflowing. Risk is defined as the product of probability and consequences. The damage in lives, property and rebuilding costs is offset against the cost of water defenses. Typical acceptable flood risks from these calculations are 1/10,000 years - 1/4,000 years for flood from the sea, 1/2,500 years - 1/100 years for a river flood. The established policy forces the Dutch government to increase defenses as new data on threat levels becomes available. The North Sea flood of 1953 and the associated storm combined to create a major natural disaster which affected the coastlines of the Netherlands and England on the night of 31 January 1953 – 1 February 1953. ...

Examples of polders

Belgium

• De Moeren, near Veurne in West Flanders

Veurne is a municipality located in the Belgian province of West Flanders. ... West Flanders (Dutch: West-Vlaanderen) is the westernmost province of Flanders and of Belgium. ...

Canada

• Holland Marsh

Holland Marsh is a farm-producing flatlands that much of the area that used to be a swamp. ...

France

• Marais Poitevin
• Les Moëres

The Marais Poitevin, also known as Venise Verte is a marsh region in Western France, a remnant of the former Gulf of Poitou. ...

Germany

• Altes Land near Hamburg
• Blockland & Hollerland near Bremen
• Nordstrand, Germany
• Bormer- und Meggerkoog near Friedrichstadt

Nordstrand / Noordströön Nordstrand (Frisian Noordströön) is one of the North Frisian Islands on the North Sea coast of Germany. ... Friedrichstadt / Frederikstad Friedrichstadt (Danish: Frederikstad) is a town in the district of Nordfriesland, in Schleswig-Holstein, Germany. ...

Great Britain

• Traeth Mawr
• Sunk Island (on the north shore of the Humber east of Hull)
• Parts of The Fens
• 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

The Traeth Mawr (Welsh for big sand) is a polder near Portmadoc in Gwynedd in Wales. ... Sunk Island is a small village in the East Riding of Yorkshire, England. ... River Hull tidal barrier. ... Hull or Kingston upon Hull is a British city situated on the north bank of the Humber estuary. ... The Fens may also refer to the Back Bay Fens, a park in Boston, Massachusetts. ... For other meanings of Essex, see Essex (disambiguation). ... The River Plym is a small river in Devon, England. ... This article is about the city of Plymouth in England. ... Grange-over-Sands is a town in Cumbria, England, and in the traditional county of Lancashire. ... This is the top-level page of WikiProject trains Rail tracks Rail transport refers to the land transport of passengers and goods along railways or railroads. ... In order to keep a road or rail line straight and/or flat, and where the comparative cost or practicality of alternate solutions (such as diversion) is too prohibitive, the land over which the road or rail line will travel is built up to form an embankment. ...

Italy

• Delta of the river Po such as Bonifica Valle del Mezzano

PO may stand for: Pareto optimality Parole Officer Per os, Latin for by mouth or orally Perfect Orange a third wave ska based in Knoxville, TN from 2002-2005 Petty Officer, a Non-Commissioned Officer Rank in many Navies Pilkington Optronics, now Thales Optronics Pilot Officer, a junior commissioned rank...

The Netherlands

• Alblasserwaard polder, which contains the famous windmills of Kinderdijk, a World Heritage Site
• Beemster, also a World Heritage Site
• Haarlemmermeer polder, which contains Schiphol airport
• Noordoostpolder
• Wieringermeer
• Eastern and Southern Flevoland polders, which contain the cities of Lelystad and Almere, respectively. Together these two polders are often referred to as the Flevopolder.

The Alblasserwaard is a country region in The Netherlands in the south of Zuid-Holland province, east of Rotterdam. ... The windmills of Kinderdijk Kinderdijk is a village in the Netherlands, partly in the municipality Nieuw-Lekkerland, partly in the municipality of Alblasserdam. ... A UNESCO World Heritage Site is a specific site (such as a forest, mountain, lake, desert, monument, building, complex, or city) that has been nominated and confirmed for inclusion on the list maintained by the international World Heritage Programme administered by the UNESCO World Heritage Committee, composed of 21 State... Beemster (population: 8,541 in 2004) is a municipality in the north-western Netherlands, in the province of North Holland. ... Haarlemmermeer (population: 127,750 in 2004) is a municipality in the north-western Netherlands, in the province of North Holland. ... Air Traffic Control Towers (ATCTs) at Schiphol Airport Schiphol (municipality Haarlemmermeer) is the Netherlands main airport. ... Noordoostpolder is a municipality in the Flevoland province in the central Netherlands. ... Wieringermeer (population: 12,583 in 2004) is a municipality in the north-western Netherlands, in the province of North Holland. ... Flevoland is a province of the Netherlands. ... Lelystad ( ▶ (help· info)) is a municipality and a city in the centre of the Netherlands, and it is the capital of the province of Flevoland. ... For other uses, see Almere (disambiguation). ...

Poland

• Vistula delta near Elblag and Nowy Dwor Gdanski
• Warta delta near Kostrzyn nad Odra

For other uses, see Vistula (disambiguation). ... Motto: none Voivodship Warmia-Masuria Municipal government Rada Miejska w Elblągu Mayor Henryk Słonina Area 83,32 km² Population  - city  - urban  - density 130. ... Nowy Dwór Gdański is a town in Poland, capital of Nowy Dwor Gdanski County, located in Pomeranian Voivodship, with 10,200 inhabitants (1994). ... Warta (Latin: Varta, German: Warthe) is a river in western-central Poland, a tributary of the Oder river. ...

United States

• New Orleans

New Orleans is the largest city in the state of Louisiana, United States of America. ...

External links

• Polder landscapes in the Netherlands within a northwest European context

References

• 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. Rapport 358.
• Morten Stenak. 2005. De inddæmmede Landskaber - En historisk geografi. Landbohistorik Selskab.
• Ven, G.P. van de (red.) 1993. Leefbaar laagland: geschiedenis van waterbeheersing en landaanwinning in Nederland. Matrijs, Utrecht.
• Wagret, P. 1972. Polderlands. London : Methuen.

See also

• Afsluitdijk
• Land reclamation
• IJsselmeer
• Zuiderzee Works
• Windpump