Land drainage strategies to cope with climate change in the Netherlands.

Since the Middle Ages the Dutch have reclaimed many lakes and parts of the sea, creating polders. Drainage is required to use the land: for the inhabitants, for agriculture and for nature. Traditionally drainage was by gravity: through open (and later pipe) drains excess rainfall was transferred into open collector drains, from where the water was pumped out to a river, lake or the sea. Since the 1950s, land use has been changing towards a more diverse and intensive agriculture, more attention for nature, recreation and continuing urbanization. On top of this, the climate is changing: significant increases in precipitation, both average and extreme. Until recently, the solution to more excess water was to increase pump capacity. Yet the combined problems of climate change, sea level rise, subsidence and urbanization require more structural changes in water management. Drainage systems have to be modified to enable the shift from a strategy of rapid removal of all excess water to one that continuously controls water levels individually in each agricultural plot. A new approach of ‘retention, storage and controlled removal’ is being used to develop climate adaptation scenarios for the three hydro-ecological zones in the Netherlands, i.e.: (1) the man-made polder areas with marine clay soils along the North Sea coast and the former Zuider Sea; (2) the low-lying peat lands in the west and north; and (3) the sandy and loamy soils areas in the centre, south and east. New approaches for tailor-made drainage solutions following this strategy are being tested in various pilot areas in the three zones. Although the research is still ongoing, this paper presents the lessons learned to date related to the challenges, risks and limitations associated with the introduction of these new drainage strategies for coping with climate change in the Netherlands. [ABSTRACT FROM AUTHOR]