The outstanding contribution made by the people of the Netherlands to the technology of handling water is admirably demonstrated by the installations in the Kinderdijk-Elshout area. Construction of hydraulic works for the drainage of land for agriculture and settlement began in the Middle Ages and have continued uninterruptedly to the present day. The site illustrates all the typical features associated with this technology – dykes, reservoirs, pumping stations, administrative buildings and a series of beautifully preserved windmills.
The formation of the peat region of the Provinces of Holland and Utrecht began around 4000 BC and continued up to the beginning of the present era. Changes in the drainage of the region consequent upon cultivation resulted in a situation where farmlands lay below the level of the streams that had drained the peat. It therefore became necessary to construct dikes to prevent flooding of the land.
There has been human settlement in the HollandUtrecht peat region since the 11th century AD, on higher land, on the embankments, and along the rivers and watercourses. The medieval developments were mostly subdivided into long strips averaging 14m wide by 1250-l300m long, with farms at their ends.
Reclamation of the Alblasserwaard ( -waard = "land in or along the water"), part of which is the subject of this nomination, began on the northern, western, and southern sides in the 11th century, and later extended to the watercourses that traverse it. A low-level ring dike enclosed all except the western part as early as the 12th century, and this had been extended to include the whole area by 1320. The Alblasserwaard was crossed by two streams, the Alblas and the Giessen, the basins of which developed into De Nederwaard and De Overwaard respectively; the Alblas was extended by a man-made watercourse, the Graafstroom, around 1264.In 1277 Count Floris V of Holland set up a central body to be responsible for the maintenance of the dikes in the Alblasserwaard, known as the Hoogheemsraadschap van den Alblasserwaard (District Water Board for the Alblasserwaard). It consisted of a dike reeve and 13 board members.
Prince Albrecht van Beieren (Bavaria) authorized the digging of a canal for draining De Overwaard from the Giessen to the river Lek at Elshout in 1365. Known as the Grote or Achter W aterschap (Large or Rear Internal Drainage District), it was 17km in length, with 12km of connecting watercourses. Four years later work began on another drainage canal, known as the Nieuw Waterschap, from the Alblas to the Lek. Both systems are still fimctioning today.
In 1612 the internal drainage district of De Nederwaard was granted a permit for the compulsory purchase of 70ha of polder-land to the west of the Nieuw Waterschap in order to increase the capacity of the reservoirs by creating a new elevated reservoir. This also involved raising the water-level in the reservoirs and, as a result, the levels of the roads and low-level inner dukes in the area all had to be raised.
Serious flooding in 1726 led to the decision being taken by the Nederwaard and Overwaard management boards each to build a series of eight "head" drainage mills to deal with the endless battle against water and transfer the water produced at that time by 43 polder mills from the lower to the elevated reservoirs. In 1740 a second sluice was installed at the elevated reservoir to handle the water flow, and in 1766 the elevated reservoir itself had to be enlarged.
However, this form of drainage using windmills proved to be inadequate, since the water-levels in the rivers were often too high, making it difficult to discharge water into them through the sluices from the lower reservoir. By 1860 the 25 mills in De Nederwaard could no longer cope, and so a steamdriven pumping station was installed in 1868, to raise water from the lower to the upper reservoir (successively replaced by modem equipment). A similar decision was taken on De Overwaard.
As a result of this process of modernization, the redundant wind-driven scoop mills were gradually demolished. The Kinderdijk mills came back into use during World War ll, when there was no fuel for the diesel-fuelled pumping station, but closed down again after 1945. Today eight polder mills survive in both De Overwaard and De Nederwaard