What is M³ about?

The Water Framework Directive (WFD) schedule has set the definition of the programme of measures (POM) in 2009 as a milestone in the endeavor of achieving good ecological status of waters by 2015. The definition of the POM for achieving good ecological status in water bodies should ideally be the optimized combination of measure implementation costs and ecological effects. In real life, the POM will be the result of a political compromise and the level of detail in the planning and the arguments or the data that support the choice of a specific measure will be highly variable. Hence, there is a need for scientific accompanying actions that will guide and benchmark the intended measures in the course of their realization. This is especially true for the less obvious environmental pressures on water bodies. However, so far there are only very few tools for evaluating measures with respect to their effect on the ecological status of surface water bodies.

A good deal of the pollution causing poor ecological status of waters is of diffuse origin, i.e. the activities and processes generating the pollution are distributed in space and can show substantial local and temporal variability. The characterization of the magnitude and spatial distribution of diffuse pollution relies on loading models. These models attempt to quantify the sources by linking mean emission values to the type of emission sources and their distribution in the catchment. This approach might, however, be biased due to a poor comparability with the nature and scale of the case studies underlying the calibration or setup of the model.

Direct measurement of source emissions is impracticable due to the multitude of sources and their non-steady emission behavior. Therefore, the realism or accuracy of pollution load predictions by the models can only be validated through immission measurements in the water bodies themselves, whose location, sampling frequency and observation period need to be chosen in a manner that they can capture the pollutant mass flows in a representative and accurate way. As there is no unique sampling scheme for pollutants with different environmental behavior, monitoring immission situations is a major challenge for water authorities. Poor accuracy and precision of immission situation characterization can lead to erroneous conclusions on most effective measures to be taken or can inhibit the clear proof of improvement of the immission situation after the measure implementation as compared to a reference state.

The efficiency of programs of measures can be simulated with emission and immission models. Yet the confidence in model predictions needs to be quantified in order to allow for sound decision support. Tools for analyzing the uncertainty of input data and how errors propagate through models have been elaborated in scientific projects. Yet, there are no ready-made solutions to decide on the optimal design of monitoring and its interplay with model performance in order to achieve maximal accuracy.

The M3 project will use existing tools and test them in the field with monitoring data of variable density in catchments of different scale and pollutant load. The chosen river basins are subject to different environmental pressures, are located in three different Member States with differing programs of measures and are covered by distinct monitoring programs. In this way, reliability of model predictions for different program of measures will be demonstrated and it will be shown that the concept is applicable in different Member States and within different river basins.