Case study 1 - Rijnland Water System

Rijnland is a polder area in the western part of the Netherlands, bordering the North Sea ( Figure 4.1 ). The total area is about 1000 km 2 of which 72% is occupied by low-lying land-reclamation areas, 15% by free draining areas and 8% by dunes. A storage basin consisting of inner connected canals and lakes, occupies 45 km 2 . The storage basin serves to collect all the excess water of the Rijnland area, before it is discharged to the main water system of the Netherlands and finally to the North Sea. The low-lying areas would be subject to flooding if they were not protected by dikes and the excess water not pumped to the storage basin. The water level in the storage basin is kept between predefined bounds, mainly by the daily operation of four large pumping stations: Halfweg, Katwijk, Spaarndam and Gouda. The total capacity of these four pumping stations is 154 m 3 /s (13.3 mm/day). In case of extreme events also pumping station Leidschendam may be used to discharge water to the Delfland Water Board (8 m 3 /s).