Jahresberichte der Wasserwirtschaft ade! Das Thema ,,Hochwasserschutz bleibt aktuell : Auenregeneration durch Deichrück-verlegung? Bodenkundliche Aspekte, aufgezeigt am Beispiel der Mittelelbe

In the floodplain of the lower Middle Elbe near Lenzen, dike strengthening has become necessary. Therefore it is intended to relocate the dike into the embanked area. In order to document the present state of the alluvial soils and to forecast changes in their balances of water and particulate resp. soluble matter, approx. 900 consistent and 1700 water samples were analysed for nutrients and trace metals. At six sites, which were characteristic of the study area, the dynamic soil parameters (soil-water content, soil-moisture tension, redox potential, soil temperature) were measured from August 1997 to December 1999. As a positive consequence of the planned dike relocation, the water balance of the soils in the relocated dike area will exhibit typical floodplain dynamics. On the other hand, the entries of particulate pollutants will effect sustainable negative changes. Considering all aspects of the prognosis, the protection of processes has to be preferred to the environmental protection. Therefore, the backward relocation of the dike has to be favoured.