Integrated river assessment by coupling water quality and ecological assessment models

The European Water Framework Directive has a high impact on current watermanagement in Belgium. Several restoration scenarios have been worked out by thegovernment. To compare the effect of these scenarios, a combination of a water quality(PEGASE) and ecological assessment models (data driven models based on regression trees)has been developed and applied for the major part of the large river systems in Flanders(Belgium). The simulation results illustrate that the currently foreseen investments in waterquality improvement will lead to drastic improvements of the ecological water quality, but arenot enough to meet the target status in most of the streams in Flanders. Moreover, more dataare needed to improve the quality of the ecological assessment models, in particular fromstream systems characterised by a high ecological quality.