Jerry Van Eyck, ASLA, of Melk! explained how the Netherland’s efforts over the past few hundred years to “control and conquer” its landscape have been driven by its “aggressive” need to create more land for dairy and agricultural production. The development of Netherlands’ system of dikes and reclaimed land has also been driven, more defensively, by its need to “keep feet dry and survive.” However, now, the country is ceding land back to the sea in a calculated retreat and creating “soft coastal engineering” systems to protect against sea level rise.
The Dutch have always “controlled and conquered water” for their own economic benefit. Like colonization, which led to a massive expansion of Dutch land overseas, water management and land reclamation has been a process of domestic expansion.
A few strategies have been used over the past hundred years:
Terps: Since before 500 BC, early Dutch were creating “terps” or hills to escape rising sea waters.
Dikes: These are systems for controlling rivers. In between summer and winter dike lines are flood plains that manage flood water. Given more than 50 percent of the Netherlands is below sea level, a system of dikes has been in constant use for a few hundred years to reclaim and then protect land.
Polders: More than 3,000 “polders” or reclaimed lands are in place across the country. Since the early 1600’s, polders have turned “swampy, peaty, warm, humid places” into land that can be farmed out. For centuries, dikes were first created in a circle around a piece of land and then windmills were used to pump out the water. Later, steam-based pumping stations made the creation of polders industrial, “enabling higher levels of reclamation.”
Two major land reclamation efforts include the “Zuidersee works” along Amsterdam and the “Delta works” in the southwest corner of the country.
The Zuidersee works enabled “huge land reclamations” and featured a closure dike some 20 miles long. The soils on the reclaimed land, once desalinated, were found to be particularly fertile and suited for cow grazing and agricultural production. At the same time, they were also a disappointment in terms of population expansion — few wanted to move into these flat, desolate areas at first.
The Delta works uses a pair of massive revolving doors to control water levels. “Each door is as big as the Eiffel Tower.” Storm surge barriers are something out of “Star Wars” — “They are science fiction” made real.
Due to increased dairy and agriculture production efficiency, polders once used for farming are now being sold back to local governments for use as new suburbs. Some three percent of Holland’s population produces agriculture in such an efficient way that the country is one of the top three exporters of agricultural products worldwide (behind the U.S. and France).
On climate change, Van Eyck says the Dutch don’t have all the answers. “Nature always fights back somehow.” Soils are shrinking, putting land back below sea levels again. Weather changes are creating monsoon-like rains, meaning some dikes won’t be able to hold the increased water flow. With increased water flow, the soil balance is also changing, “deteriorating.”
The Netherlands is now going through a process of “de-polderization,” a calculated retreat where land is given back to the water. The country’s landscape architects are also creating a new system of “soft infrastructure” along the coasts to protect the country against climate change-induced rising sea levels. “We discovered we can’t put more dikes, or ‘hard’ infrastructure in place to control against sea level rise — water seeps through the weak spots. Instead, we need to use ‘soft coastal protection.'”
These soft coastal engineered systems, or “sprayland” consists of mud that has been sprayed under water for years, creating strips of coastal land. Airplanes then throw Buckthorn bush seeds out in order to vegetate these strips. Bulldozers then come in to create fire escape lines through the vegetation.
Van Eyck said the world sees the Netherlands as experts in water management, but increasingly, “there’s no solution to climate change,” only combinations of engineered hard and soft protections.
Image credit: Dutch Dike, Wikipedia Commons