Over the last decades, significant efforts have been made in Germany to improve the quality of surface waters. These measures have led to significant improvements in the water quality of most rivers and lakes. However, comparably little attention has been paid so far to the enhancement of the morphological structure of surface water bodies such that water of good quality is now often flowing through or residing in water bodies characterised by poor morphological conditions. Consequently, in spite of all the improvements already achieved, the ecological functioning of many water bodies in Germany is still limited.
The European Water Framework Directive (EU-WFD) which entered into force in 2000, aims at improving the ecological state of the European water bodies by the year 2015 (WRRL, 2000; BMU, 2011).
It has been implemented into national German law in 2002 („Novellierung des Wasserhaushaltsgesetzes") and again in 2010 („Neufassung des Wasserhaushaltsgesetzes").
The ecological state is assessed by a number of biological criteria such as the occurrence of a number of sensitive species. The morphological structure plays a key role in this context and a number of methods have been developed in Germany to assess the morphological state of rivers and streams as well as lake shores.