Three years ago, the Hunze en Aa’s water board raised the bottom of three Drenthe deeps in an attempt to improve nature in and around the stream and to use the stream valleys for water collection. About 40 centimeters of sand with wood material has been introduced.
One of those deeps is the Anlooërdiepje. The idea was that the sand would spread naturally in the stream. This is now being investigated by measuring the radioactivity in the stream bed.
“By nature, streams have depths and shallows,” says Peter Paul Schollema, ecologist at the Hunze en Aa’s water board. “If there is a tree somewhere, you often see a deep bowl in the outer bend with all kinds of fish. In the inner bend it is much shallower and more silty.”
“That mosaic of different habitats, as we call it, that variation between sand, silt and wood, ensures that many different creatures and plants can live in such a system. After introducing that sand material, we use these measurements to check whether variation between depths and shallows has been maintained.”
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