European and international examples on joint use of monitoring and modelling, both in groundwater, surface water and ecology, were presented. After this the participants were put into groups, presenting their national monitoring programmes for each other briefly and on the basis of this discussing the potentials in joining forces with modelling.

The following paradox appeared from this workshop: monitoring and modelling are at the same time inextricably linked, while having their own “raison d’être” independently. However, in the scientific community the joint use of monitoring and modelling is a natural thing – but here data collection/monitoring often is done as a campaign design especially to the chosen model. The challenge is to bring this joint use forward to the implementers of the WFD – and to convince modellers, that the current practice of data collection must form a basis for modelling and thus for potential collaboration on a joint development of a better monitoring system, by the use of models.

Good reasons to use monitoring in itself for the WFD are to obtain real world data on status and trends. Good reasons for using models in itself for the WFD are to analyse implications of government policies. However, models need monitoring to calibrate, improve and to be able to predict trends.

The following were pointed out as situations, where monitoring and modelling should join:

• To improve data analysis/quality assurance: outlier detection, accident reporting, etc.

• To extract more information from the data: trend detection, intervention analysis, interpolation in time and space

• To improve the conceptual understanding of a given water system

• To assess effects of pressures

• To include interactions between groundwater and surface water

• To group water bodies in a representative manner (e.g. for 1000 lakes, measure in 10)

• To define reference conditions

• To describe temporal and spatial variability (e.g. eliminate redundant sampling points)

• To optimise monitoring networks to get more informative data thus reducing costs

From the different inputs at the workshop it became obvious that the individual countries stand at very different ground with respect to the implementation of the monitoring objectives of WFD. Achieving the WFD objectives and sticking to the deadlines is not an easy task!

The workshop was held in Ghent, Belgium, in April 2005.