stones; large woody debris (LWD), roots or aquatic plants can also have a supporting effect. Degradation stretch A degradation stretch is a river section that by definition meets none of the criteria to be a beam origin nor a beam path. Transverse structures such as weirs or dams can be obstacles for aquatic organisms but also canalised (artificial) river sections possibly prohibit organism to drift and migrate. See also River ecosystem Integrated water resources management Aquatic ecosystem References Environmental engineering Hydraulic engineering Hydrology Aquatic ecology Water and politics Water resources management