How to deal with cost-efficiency aspects at the set-up of programmes of measures

The achievement of good ecological and chemical status of rivers is the main objective of the European Water Framework Directive (WFD). According to Annex III of the WFD, necessary measures within a possible field of action are to be chosen taking into account their cost efficiency and cost effectiveness. One of these fields of action is, for example, river morphology. In view of the given deficits in the morphological structures of the German rivers, concepts for morphological improvement have been drawn up for many rivers, resulting in the elaboration of a multitude of different appropriate measures. In order to evaluate these measures with respect to the objectives of the WFD, a methodology was developed that showed the relationships between the assessed efficiency of measures, the length of the river stretch being influenced by these measures, and the estimated costs. Result is a cost-efficiency quotient that can serve as a supporting factor in helping to set the right priorities. The methodology was tested in a subcachtment of the Ruhr River basin and proved to be useful for the given purpose. In general, the applied methodology is not limited to morphological measures, but also applicable to other fields of action in the sector of water and river basin management.