Do the WFD monitoring programmes provide sufficient data for modelling?

According to the WFD Guidance Document on Monitoring, monitoring can support various objectives. Depending on these objectives the monitoring can be characterised as (a) surveillance monitoring, (b) operational monitoring, or (c) investigative monitoring with increasing requirements to the monitoring programmes. The document does not directly specify the need for using models and the associated data needs, but considers modelling a supporting tool. The present paper analyses to which extent the WFD monitoring programmes can be expected to provide sufficient data for the expected modelling in the WFD implementation process - based on the principles laid down in the WFD guidance documents. We proposed an analysis of the required confidence versus the actual confidence acquired. If the available data alone is not sufficient to achieve the required confidence modelling may be considered, in this case the data requirements are defined by the data required for modelling and as such, the WFD monitoring programme does in principle provide sufficient data for modelling.