Polders in the Netherlands

All of west Netherlands except rivers and dunes is below sea level, separated into hydrological units called polders.

These properties, their dikes, and the interconnected waterways evolved as the ground subsided. Although below the water table now, most polders began as rudimentary farms on peat bog just above sea-level.

Delta peat, barely soil at all, can be made arable with extensive work. Exposed to oxygen, it decomposes. This land has been subsiding since the beginning of agriculture here. The drainage of excess water today perpetuates the oxidation of peat-bog soil.

There had been polders along the coastline in ancient times that released water at low tide; but the great majority have been formed at inland farms where drainage to outside water had become increasingly problematic. Here, the modern techniques evolved. Most polders were created not for landwinning but to drain and keep dry a subsiding piece of land.

During the 17th century, there came projects that indeed made land of watery territory. By the time of the Golden Age, there were powerful standard-model water windmills, and the enormous wealth of the era permitted their deployment in huge numbers.

In 1612 the Beemster was dry. It had been a lake made by peat harvest and eroded by stormflood into a problematic arm of the Zuiderzee. Following the technical (eventual) success and enormous profitability of the drainage and division of the Beemster into farmland parcels, the rest of the delta's shallow lakes were dried within the next few decades. Political will was easy because the lakes were a stormflood hazard and an erosion menace — and there was plenty of capital for good lakebed farmland.

It wasn't until 1811 that anybody would initiate another major landwinning project, the Zuidplaspolder in South Holland province. Centuries of peat harvest had led to lake Zuidplas, tens of meters deep and a menace to bordering properties. Also, the 19th century brought again a high demand for arable property. Gangs of windmills emptied Zuidplas. A few decades later the Netherlands' first large steam pumping station assumed maintenance drainage.

The steam pump came into its historical moment in the early 19th century when the technology coincided with sufficient political will to drain the great Haarlemermeer, a troublesome body of water in the south of North Holland province. Adjacent municipalities had since the Middle Ages harvested peat from the deepening beds of lakes that had eroded into one lake that ate villages during stormy weather. Three pumping stations drained Haarlemermeer between 1848 and 1852.

In 1891 the engineer Cornelius Lely drafted a plan for closing the Zuiderzee, a great shallow sea extending into the heart of the Netherlands. There was opposition, but Zuiderzee was dangerous in proportion to its size. After the 1916 flood, "Plan Lely" became reality. A 1918 law decreed the closure and impoldering of the Zuiderzee. The first world war delayed execution but also showed importance of expanded farmland and food security.

An experimental polder completed in 1927 showed the arability of dried seabed. In the next few decades large electric pumping stations claimed more than 1700 square kilometers of the former Zuiderzee (now freshwater lake Ijselmeer.) Among the newly-created territory was Flevoland, the twelfth province.