Bart Schultz
The Haarlemmermeer Polder was drained between 1848 and 1852 as an agricultural polder. However, in 1916, permission was obtained to designate 16.5 hectares of land in the Haarlemmermeer Polder for a military airfield. This decision led to enormous development in the polder, as the newly established KLM subsequently opened its first scheduled service from Amsterdam to London from this airfield in 1920. Since then, the airfield has been regularly expanded into the current Schiphol, where a total of no fewer than 67 million passengers departed from or arrived in 2024. Most passengers will not have been aware that this took place at approximately 4 metres below NAP (Amsterdam Ordnance Datum).
Due to its central location in the Randstad, as well as the economic activities developed primarily in relation to Schiphol, urban and industrial areas have expanded enormously, particularly in the northern part of the Haarlemmermeer Polder, resulting in a polder with multiple land use. For instance, the number of inhabitants in Hoofddorp and Nieuw-Vennep, the two largest centres in the polder, was 73,600 in 2020. By 2024, the number of inhabitants had already increased to 112,000.
The value of built-up areas has also increased enormously. For instance, the WOZ value (Valuation of Immovable Property) was 34.4 billion euros in 2020. These rapid developments have also had consequences for water management and flood protection in the Haarlemmermeer Polder, and for the level of safety of the ring dike.
Immediately after the land reclamation, responsibility for water management and flood protection was with the Commission of Management and Supervision, which had also been responsible for the reclamation. In 1855, the Water Authority De Haarlemmermeer Polder was established, which took over the responsibility for the water management and flood protection from the Commission in 1856.
In 1979, the Water Authority Groot-Haarlemmermeer was established as part of a merger of 21 Water Authorities, including the Water Authority De Haarlemmermeer Polder. Subsequently, in 2005, several Water Authorities, including Groot-Haarlemmermeer, merged into the Principal Water Authority of Rijnland. Since then, water management and flood protection in the polder have been the responsibility of this Principal Water Authority.
The choice of the preferred summer water level determined the location and dimensions of the canals and ditches, as well as the depth to which the three steampower pumping stations – Cruquius, Leeghwater, and Lijnden – initially had to be able to pump the open water. The water management system originally consisted of a main canal with six cross canals, as well as a network of ditches and smaller canals. The land division was characterized by longitudinal roads running northeast/southwest at intervals of 2 kilometres, crossed by cross roads every 3 kilometres. The canals and ditches were predominantly constructed alongside the cross roads and parallel to the longitudinal roads at intervals of 1 kilometre.
Originally, a parcel width of 50 metres was proposed. However, primarily for cost-saving reasons, a parcel width of 200 metres and a length of 1 kilometre were chosen. As a result, the parcels totalled 20 hectares and were bordered by a road at the front and a ditch at the rear. It was assumed that after the sale of the land, the farmers would dig the intermediate ditches themselves.
Initially, the pumping station Leeghwater could pump the water down to 3.49 metres below NAP, and the Cruquius and Lijnden to 3.65 metres below NAP. This was based on a land subsidence of 35 centimetres after drying out.
In the early days after the draining, there were quite a few problems due to the excessive distance between the ditches and land subsidence. The open water storage and pumping capacity were insufficient to keep the lower parts of the polder dry. To improve the situation, the Regulation on the re-shooting, opening, or excavating of road and parcel ditches was adopted in 1856. However, fifteen years after draining, the problems had still not been resolved. This can also be illustrated by the saying from the early days of the polder, which goes:
"The first farmer dies,
the second is in need,
and the third has bread."
Because the polder's soil was not level, problems also arose between the highlanders and the lowlanders. The lowlanders had problems with flooding, and the highlanders suffered from water shortages during dry periods. In connection with this, they were given the option at several locations to let water in from the ring canal using siphons. However, this water could also lead to increased flooding for the lowlanders. Therefore, a number of lowlanders were given the option of sub-pumping.
As a result of requests from the landowners of the polder in 1872, lower water levels were also requested for the winter period. Steampower pumping made this possible in principle. At the end of the nineteenth century, the polder water level was maintained at 5.55 metres below NAP, and rises above 5.30 metres NAP occurred only sporadically.
From 1913 to 1952, the water level was raised by 60 – 80 centimetres in October and November - the so-called Sugar Beet Level - so that ships could transport the sugar beets. After 1952, the water level was brought back to the winter level around the end of September. Following various subsequent level reductions, the current target level in the main watercourses is now 5.87 metres below NAP in summer and 6.02 metres below NAP in winter.
Over the years, improvements have also been regularly made to the pumping stations. For instance, steam boilers were initially added. From 1911 onwards, the steam engines in the pumping stations Leeghwater and Lijnden were gradually replaced by diesel or electric engines. As a result, the total pumping capacity reached 8 millimetres per day in 1932, after which the pumping station Cruquius was taken out of operation. After a number of further replacements and improvements, the total pumping capacity amounted to 16.7 millimetres per day at the beginning of the current century.
In 2002, the electric pumping station Koning Willem I was completed, and in 2005, a new pumping station was built next to the pumping station Lijnden. This brought the total pumping capacity to 20.5 millimetres per day.
Schiphol Airport, situated in an area of 2,700 hectares, was initially part of the drainage system of the polder but received separate pumping in 1975, amounting to 16.8 millimetres per day. The pumping station Bolstra was completed in 1992, followed by the pumping station Rijk in 2001. This brought the total pumping capacity for the Schiphol area to 23.2 millimetres per day.
The ring dike around the polder was constructed in such a way that, after settlement, the crest height would be 0.69 metres above NAP, which was the customary height for dikes around drained lakes at that time. At the beginning of the 20th century, the ring dike was maintained at 0.59 metres above NAP. However, lower sections existed in various places, particularly at road intersections. Since 1903, a minimum height of 0.11 metres below NAP has been maintained. Currently, the ring dike has a level of safety with a risk of failure of 1 in 1000 per year. The crest height is at 0.00 metres above NAP, which is therefore lower than the original crest height.
In 2026 the Haarlemmermeer Polder existed for nearly 175 years and has transformed over the years from an agricultural polder into an increasingly urbanized polder. Particularly since the Second World War, significant changes in land use have occurred due to urban development, horticulture, industry, recreational facilities, and Schiphol Airport. Consequently, the polder has provided ample space for new developments on a large scale.
The water management system and flood protection have consistently been adapted to the desired level. Climate change will have a certain impact. Sound care for water management and flood protection will remain of undiminished importance. The question is how long our urbanized society can continue to provide this care adequately.
