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Water en land

Landforms   Freshwater regions   Fresh water (biotope)   Lakes (ecology)   Ditches (ecology)   Plant ecology   
Waterway by Holwerd, Friesland, Ecomare

Freshwater regions

Freshwater regions represent only a very small percentage of all the water on earth (0.0075%). Nevertheless, ditches, rivers, canals, ponds, lakes and marshes are characteristic scenic elements in the countryside which often have major natural values. This is particularly true in low lying coastal regions. Management of the inland waters must combine preservation of these nature values with the necessity for maintaining 'dry feet'.

  • Fresh water

    Fresh water is not necessarily 'fresh'. It contains much less salt than seawater, no more than a half gram per liter. Fresh and salt water are continually exchanging water via the water cycle. The fresh water on land originates from the sea as an evaporated product that contains no salt. It returns to the earth as precipitation.

  • Groundwater aquifer

    Fresh water is less dense than saline (salt) water and therefore 'floats' on it. A lens-shaped bubble of fresh groundwater lies on top of the saline water underneath elevations with infiltrated saline groundwater, as found in dunes and salt marshes. This is called a groundwater aquifer. When such an aquifer develops, plants that require fresh water will start growing.

  • Canals

    Canals are wide man-made waterways. They have three functions. Firstly, canals are for water management, particularly for rapid or slow removal of water from a region. Secondly, they serve as channels for transportation of goods and people. Sluices in the channels allow ships to move through areas with different water levels. And thirdly, canals have a recreational purpose, particularly for aquatic sports and hobby fishermen.

  • Lakes

    No large natural lakes can be found in the wadden region and bordering sea clay landforms. This is because the landform developed from an ongoing process of silting up, whereby a marsh was reclaimed as soon as the land rose above the average high-tide level. The largest freshwater lakes in the area are the Lauwersmeer and IJsselmeer, which are unnatural because they became fresh after being closed off with a dike. There are still a few smaller lakes along the streams that flow into the Wadden Sea in Groningen and Niedersachsen (Lower Saxony).

  • Ditches

    In north-western Europe on the average, there is more precipitation than water evaporation out of the ground. This is called a precipitation surplus. If this water is not removed from low lying polders, the land will become inundated and flood. To avoid this problem, polders have a network of ditches, which water managers can pump away when necessary. In earlier days, the wider ditches were also used by the farmers for transportation: cows and hay were brought from pastures to the farm with the help of flatboats and barges.