Ecomorphological survey of large rivers - Monitoring and assessment of physical habitat conditions and its relevance to biodiversity.

Abstract

An ecomorphological survey for large rivers above 10 m in width with special emphasis on navigable rivers is presented. It was elaborated on the basis of more than 500 km of survey on 8 different rivers including the major waterways in Germany. The method focuses on three quality elements of a functioning river ecosystem, i.e. hydrodynamics, morphodynamics and habitat structure. In this regard, 17 indicators are used for assessing the ecological functioning. The river system is divided into the riverbed, the riparian zones and the floodplain, each compartment being assessed with a defined group of indicators. The usual survey unit for larger rivers comprises one kilometre, some morphological indicators, however, require survey units related to bankfull width. The assessment is based on a scoring system which was defined independently of the actual survey. With a 5-step classification, the survey complies with EC standards. A preliminary analysis of the correlation between the structures of the fish and invertebrate communities and the ecological status obtained by the survey suggests that the assessment produces plausible results.