The Floodplain Index - a new approach for assessing the ecological status of river/floodplain-systems according to the EU Water Framework Directive.
Chovanec, A.; Waringer, J.; Straif, M.; Graf, W.; Reckendorfer, W.; Waringer-Löschenkohl, A.; Waidbacher, H.; Schultz, H.
A new method was developed to assess the ecological status of river/floodplainsystems. The approach is based on the requirements of biological assessment laid down in the EU Water Framework Directive, and, therefore, focuses on water bodies and their environs while neglecting truly terrestrial floodplain sections. The following indicator groups have been integrated: molluscs, caddisflies, dragonflies, amphibians, and fish. These groups were chosen to describe species associations representative of all types of floodplain waters along the gradient of hydrological connectivity. Key element of the procedure is the Floodplain Index, which is calculated for each site investigated on the basis of species-specific habitat values expressing the species' habitat preferences. Since species compositions vary according to the hydrological conditions, the water bodies of an investigation area can be characterized according to the index values. The distribution of the index values shows if and to which extent the degree of lateral connectivity is disturbed in the floodplain area. The assessment of the ecological status is based on a comparison between a river-type-specific reference condition and the status quo. The method is presented with an example from a Danube floodplain area in the north of Vienna (Austria).