Classification of quality of the water body structure
A classification of quality of the water body structure (see table below) developed by the Working Group of the Federal States on Water Issues (LAWA) describes a change in water structural quality in terms of deviation from its potential natural state (reference condition). Maps of water landscapes served to define reference conditions. On small to medium-sized watercourses, the morphological structure is assessed using either the “overview method” or the “on-site method”. The latter has been further developed for the classification of medium-size to large watercourses. These methods were used to draw up the map of water body structure.
The “overview method” uses and assesses parameters calculated on the basis of aerial pictures, existing maps and data, geological and soil maps, and especially topographical map M 1:25.000, as well as by consulting local experts. The local scale procedure is limited to exceptional cases. It is possible to assessing usually sections of 1 kilometer or more.
Unlike the overview method, the “on-site method” of small to medium-sized watercourses relies on data taken from the field (assessments of 100 meter sections). The procedure for classification and assessment of small and medium watercourses as well as mapping of medium to large watercourses generally is based on 25 individual parameters. They can be classified into 14 functional units and are aggregated into 6 main parameters, which can again be grouped into the three areas bed, banks, and land. Mapping of medium to large watercourses largely corresponds to the procedure used for small and medium watercourses, but it has been expanded to include several parameters concerning the riparian meadow.