How the Netherlands Rose from the Sea: 2,500 Years of Floods and Land Reclamation on One Map

A Country That Keeps Changing Shape

Most maps of the Netherlands show a fixed outline, as if the coast had always been where it is now. It has not. Two and a half thousand years ago the west of the country was a vast raised bog behind a line of dunes, the middle held a freshwater lake, and the north was a salt marsh where people lived on mounds. Since then the sea has taken huge areas, and people have taken them back, often more than once. Whole villages drowned in a single night; whole lakes disappeared in a few years of pumping.

This map shows that history from 500 BC to today. Its one rule is that the past should look like the present: where there was water, the map paints water in exactly the colour of the basemap's own sea, so the Zuiderzee over today's Flevoland looks no different from the IJsselmeer next to it, and the Haarlemmermeer looks like a real lake until the moment it is pumped dry. Where land has since drowned, as in Zeeland or the Dollard, the map paints land. Today's land that was won from the water is coloured by when it was won.

From Peat Bog to Inland Sea

Around 500 BC a closed coast of beach ridges and dunes protected a landscape of peat, in places metres above sea level. In the north people settled the salt marshes of Friesland and Groningen and raised their farms on terpen and wierden. The Romans, who made the Rhine their frontier, knew a lake in the middle of the country as Flevo; Drusus sailed a fleet through it in 12 BC. By the early Middle Ages it had grown into Almere, linked to the Wadden Sea by the Vlie, while a tidal inlet, the Middelzee, cut Friesland in two.

Then people started draining the peat to farm it. Drained peat shrinks and oxidises, and the land sank. Storm floods did the rest. Those of the 12th century, traditionally the All Saints' Flood of 1170, widened the openings to the sea, and St Lucia's Flood of December 1287, one of the deadliest floods in history with an estimated 50,000 to 80,000 dead, finished the Zuiderzee as an arm of the North Sea. West Friesland survived because by about 1250 its farmers had linked older dikes into the 126 km Westfriese Omringdijk.

Drowned Lands

The late Middle Ages were the worst centuries. On the night of 18–19 November 1421, St Elizabeth's Flood drowned the Grote Waard between Dordrecht and Geertruidenberg; much of it never came back and became the Biesbosch, and Dordrecht became an island. In Groningen the sea ate the Dollard out of the peat of Reiderland, decisively in the Cosmas and Damian flood of 1509; around 1520 the bay covered some 340–350 km². In Zeeland, St Felix's Flood of 5 November 1530, remembered as Evil Saturday, drowned the eastern part of Zuid-Beveland, leaving only the town of Reimerswaal on its island. Saeftinghe, on the Scheldt, lost most of its land in the All Saints' Flood of 1570 and the rest in 1584, when Dutch troops breached its last dike to stop the Spanish around Antwerp.

Windmills, Steam and Lakes Pumped Dry

Winning land back started early, with dikes around salt marshes and silted inlets, but the Golden Age turned it into an investment. Amsterdam merchants paid for windmills to pump the Beemster dry between 1609 and 1612, then the Purmer (1622), the Wijde Wormer (1626) and the Schermer (1635), so that the lakes of Noord-Holland became the geometric polders of the "Land of Leeghwater". At the same time Holland dug its own lakes: peat cut from below the water table for fuel left open water behind, much of which had to be drained again in the 18th and 19th centuries. The Zuidplas, drained around 1840, holds the lowest point of the country, almost seven metres below sea level.

South of Haarlem storms merged four lakes into one, the Haarlemmermeer, which grew from 26 km² in 1531 to about 150 km² by 1647 and threatened Amsterdam and Leiden. It took steam to beat it: three pumping stations, the Leeghwater, the Cruquius and the Lijnden, pumped 800 million tonnes of water out between 1848 and 1 July 1852.

Closing the Zuiderzee and the Delta

After the storm flood of January 1916 parliament passed the Zuiderzee Act, Cornelis Lely's plan to close the Zuiderzee and drain much of it. The Wieringermeer fell dry on 21 August 1930, the Afsluitdijk closed the sea on 28 May 1932, and the Noordoostpolder followed on 9 September 1942, in the middle of the occupation, turning the islands of Urk and Schokland into dry land. In April 1945 German troops flooded the Wieringermeer again; it was dry once more by December. Eastern Flevoland fell dry in 1957 and Southern Flevoland in 1968, together almost a thousand square kilometres of new land, now home to Lelystad and Almere. The fifth polder, the Markerwaard, was never built.

In the night of 31 January to 1 February 1953 a storm surge broke the dikes of Zeeland, South Holland and West Brabant, and 1,836 people died. The answer was the Delta Works: dams across the estuaries from the Veerse Gat (1961) to the Haringvliet and the Brouwersdam (1971), and storm-surge barriers where the water had to stay open, the Eastern Scheldt barrier (1986) and the Maeslant barrier in the Rotterdam Waterway (1997). The Lauwerszee was closed in 1969, and Rotterdam's port pushed out into the North Sea on the sand of the Maasvlakte and, in 2013, Maasvlakte 2.

How to Read the Map

Water and land of each era are drawn in the basemap's own colours: grey water is water at that moment, white land is land at that moment, whatever the modern map underneath says. Coloured areas are today's land that was once sea, tidal flat or lake, coloured by the period it was won back for good: green before 1250, yellow 1250–1600, orange 1600–1850, red 1850–1950 and purple after 1950. Land that was won, lost again and won back takes the colour of its last reclamation. Markers flag the great floods (blue), dikes and dams (brown) and polders (green).

Between the dated events the coast morphs smoothly, which is a simplification: in reality salt marshes silted up and dikes crept outward plot by plot. Gradual changes between two reconstructions are shown at a single date, and small lakes that formed and were drained between 1500 and 1850 are mostly left out.

How the Map Was Made

The land and water of each era come from the paleogeographic maps of the Netherlands by Peter Vos and colleagues (Deltares and the Cultural Heritage Agency, RCE) for 500 BC, AD 100, 800, 1250, 1500, 1850 and 2000. The changes between two of those maps were cut into pieces and dated: by the great floods for the drowned land, by the dates of the drained lakes (the droogmakerijen), by the Province of Zeeland's map of polders by embankment period, and by the official dates of the Zuiderzee and Delta Works. The extent of the 1953 flood was traced from a small-scale map by Lencer on Wikimedia Commons (CC BY-SA 2.5) and is approximate. Today's coastline is the basemap's own, taken from its vector tiles, so the past and the present line up exactly.

Chronological Timeline

• c. 500 BC — Raised bogs behind the dunes; terp settlements on the northern salt marshes
• 12 BC — Drusus sails through Lake Flevo to the North Sea
• c. 800 — Lake Almere connected to the Wadden Sea; the Middelzee cuts Friesland in two
• 1 November 1170 — All Saints' Flood
• c. 1250 — The Westfriese Omringdijk is completed
• 14 December 1287 — St Lucia's Flood completes the Zuiderzee
• 18–19 November 1421 — St Elizabeth's Flood; the Grote Waard becomes the Biesbosch
• 26 September 1509 — Cosmas and Damian flood; the Dollard reaches its largest extent around 1520
• 5 November 1530 — St Felix's Flood drowns Reimerswaal's hinterland
• 1 November 1570 — All Saints' Flood
• 1584 — Saeftinghe drowned during the Eighty Years' War
• 1612 — The Beemster is drained, followed by the Purmer (1622), Wijde Wormer (1626) and Schermer (1635)
• c. 1647 — The Haarlemmermeer has grown to about 150 km²
• c. 1840 — The Zuidplas is drained
• 1 July 1852 — The Haarlemmermeer is dry
• 13–14 January 1916 — Zuiderzee flood; Zuiderzee Act in 1918
• 21 August 1930 — Wieringermeer dry
• 28 May 1932 — The Afsluitdijk is closed
• 9 September 1942 — Noordoostpolder dry
• 17 April 1945 — German troops flood the Wieringermeer (dry again 11 December 1945)
• 1 February 1953 — North Sea Flood, 1,836 dead in the Netherlands
• 29 June 1957 — Eastern Flevoland dry
• 29 May 1968 — Southern Flevoland dry
• 23 May 1969 — The Lauwerszee is closed
• 4 October 1986 — The Eastern Scheldt barrier opens
• 10 May 1997 — The Maeslant barrier opens, completing the Delta Works
• 22 May 2013 — Maasvlakte 2 opens