14. Quantitative Evaluation of Hydromorphological Changes in Navigable Waterways as Contribution to Sustainable Management

A quantitative evaluation method called Valmorph (eVALuation of MORPHology) was developed by the German Federal Institute of Hydrology (BfG). It was used to identify hydromorphological changes based on representative hydromorphological indicator-parameters. Information on reference conditions representing the basis for any hydromorphological assessment was derived from historical data analysis. By comparing recent and historical data, an evaluation is possible, in which historical data are assumed to represent natural or near-natural conditions. Outputs of this procedure are critical river sections in terms of hydromorphological attributes. BfG evaluated changes in hydromorphological characteristics for the German part of the inland Elbe River (from the Czech border to the tidal weir at Geesthacht—586 km). This work was done on the request of the Elbe River Basin Association and contributes to the Sediment Management Plan for the Elbe River. For the Elbe River an example is presented using the parameter “structure of the riparian zone”, which is of particular interest because it has a natural function as a source and sink for sediments. Changes in the riparian zone (e.g., bank fixation and groyne fields) have a large effect on river morphology and could also have considerable effects on habitat development and distribution. The evaluation results were summarized in their entirety for the six investigated hydromorphological parameters used as indicators for river sections in a poor hydromorphological condition. This serves as a basis for making well-reasoned decisions on measures and management options to improve hydromorphological characteristics and support the prioritisation of measures in decision-making processes.