Harmonised Inventory of Point and Diffuse Emissions of Nitrogen and Phosphorus for a Transboundary River Basin
The European Water Framework Directive (WFD) demands for all river systems and the coastal zones of the European seas to reach a good ecological status within the next decade. In addition to the fact that there is an urgent need for the definition of “good ecological status”, one of the most important tasks will be to evaluate the present status of the ecosystems and the point and diffuse sources of the polluting emissions into these systems. Based upon this analysis of the present state and comparison with the target state, appropriate measures have to be developed in order to reach the necessary good ecological status. Costs can then be estimated for the implementation of the measures. During the last decade significant progress was made with this process for national rivers, especially for the nutrients phosphorus and nitrogen. However, it has been unclear which tools and models can be used for the analysis of large transboundary river systems where it is especially necessary to establish far as possible a unified database and harmonised model approach. Without this unification and harmonisation there is a risk that evaluation of the present situation, and the subsequent development of proposed measures, will differ greatly due to the application of different tools for the individual regions of the river system. An analysis of the Odra river basins (Behrendt et al., 2003) showed that the MONERIS model for the estimation of the point and diffuse nutrient emissions into medium and large river systems can be used also for such a task outside of German river systems. But the Odra is a relatively simple example of a European transboundary river system since the basin is dominated by one country (Poland) and the hydrological conditions are actually similar to some river systems of Eastern Germany. The analysis of the point and diffuse emissions within the Danube basins is, compared to the Odra, a much more difficult task since the Danube is the second largest river system in Europe and about 7 times larger than the Odra. Furthermore, a total of thirteen countries have to be taken into account with a wide range of socio-economic conditions, while the hydrological situation differs very much in parts of the Danube basin in comparison to German river basins. In order to address these issues a project funded by the German Environmental Agency was started in 2000. The project was focused on three objectives. Firstly, the tools and models that have been developed for each emission source needed to be tested in the Danube basin for their description of the nutrient flow from the emission sources to the riverine transport systems. Secondly, a harmonised spatial digital database for the whole Danube basin was to 1 Introduction 2 be prepared which could be used by the International Commission for the Protection of Danube River (ICPDR) for further analysis. Thirdly the established harmonised database was to be used in combination with the model to estimate possible changes of the nutrient state of the Danube river based on upon different scenarios for diffuse and point emissions. For the achievement of these objectives it was necessary to incorporate scientists from the most of the Danube countries into the study team and to cooperate very closely with the different working groups of the ICPDR as EMIS and TNMN. One year after the begin of this project the EU-project daNUbs (“Nutrient management in the Danube Basin and its impact on the Black Sea”; EVK1-CT-2000-00051) was started. Within the daNUbs project our group has the task of the estimation of the nutrient emissions by point and diffuse sources within the different subcatchments of the Danube and the nutrient load within the main river system as the input for the Danube Water Quality Model (DWQM). The estimation of the nutrient emissions should be done for the present state but also for different scenarios for the further development. The cooperation within the framework of the daNUbs project and the financial support of this project was an urgent help for us to solve the manifold problems in relation to the database as well as the modification of the model approaches to such a large river basin with different climatic, hydrological and socio- economic conditions. Especially the application of the model MONERIS to different case studies in the Danube river basin by different national groups and coordinated by the University of Technology Vienna was and will be very helpful also for the modelling of the whole river basin. Therefore we can conclude that the results presented in this report were only be possible in relation to the spatial resolution as well as the quality of the calculations by the combination of the work within both projects. The following research report shows all of the results, which may be interesting for other scientists working in this field as well as the further work of the International Commission for the Protection of Danube River. Additionally we will derive tasks for further developments regarding the database and the modelling tools to get a better description of the present status of the nutrient emissions into the river system of Danube and availability to estimate changes of the status in the past and in the future.
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