Regionale Aspekte des Feststoffmanagements als Grundlage für den naturnahen Wasserbau im Mühlviertel und im Bayerischen Wald

Abstract

The aim of near-natural river engineering is to consider natural and near-natural framework conditions and processes in the planning of river engineering projects like flood protection or bank stabilization measures – a context in which the mid to long-term monitoring of sediment and sediment dynamics plays a central part. With regard to natural and anthropogenic changes, deficits and surpluses of sediments can result in massive and sustainable changes in habitat quality of rivers. Especially in the region of the Bohemian Massif, a surplus of coarse sand and fine gravel (grain size 1 to 10 mm) is the cause of regional problems, both in terms of flood protection and freshwater ecology. Basic and applied research conducted in the project “Sediment management in the Mühlviertel and the Bavarian Forest” documented not only the status quo of eight selected catchment areas, but also yielded valuable insights into the causes and interrelations responsible for river bed degradation due to coarse sand inputs. In addition to agricultural and forest management aspects like the open drainage of meadow ditches or the influence of spruce monocultures, the impacts of global warming (increased frequency of heavy rains) and sediment transport dynamics were identified as the major causes of the increasing degradation of aquatic habitats and the need for an integrative sediment management in the investigated rivers. The results presented in this paper deliver important information for future near-natural river engineering measures in order to restore rivers in the region of the Bohemian Massif.