Björn Tetzlaff

Forecasting the effects of EU policy measures on the nitrate pollution of groundwater and surface waters

We used the interdisciplinary model network AGRUM [corrected] to predict the actual mean nitrate concentration in percolation water at the scale of the Weser river basin (Germany) using an area differentiated (100 m x 100 m) approach. AGRUM [corrected] combines the agro-economic model RAUMIS for estimating nitrogen surpluses and the hydrological models GROWA/DENUZ for assessing the nitrate leaching from the soil. For areas showing predicted nitrate concentrations in percolation water above the European Union (EU) groundwater quality standard of 50 mg NO3-N/L, effective agri-environmental reduction measures need to be derived and implemented to improve groundwater and surface water quality by 2015. The effects of already implemented agricultural policy are quantified by a baseline scenario projecting the N-surpluses from agricultural sector to 2015. The AGRUM [corrected] model is used to estimate the effects of this scenario concerning groundwater and surface water pollution by nitrate. From the results of the model analysis the needs for additional measures can be derived in terms of required additional N-surplus reduction and in terms of regional prioritization of measures. Research work will therefore directly support the implementation of the Water Framework Directive of the European Union in the Weser basin.

Sustainable use of water resources in Europe and the role of integrated modelling of phosphate fluxes.

Sustainable management of European water resources is advanced by the implementation of the Water Framework Directive. To achieve its aims the directive requires the realisation of cost-efficient programmes of measures. In this context, also measures for reducing phosphate inputs have to be taken, which demands models as quantification tools for the status quo analysis as well as for scenario analyses. An area-differentiated model approach (MEPhos) for the systematic quantification of P-inputs from point and diffuse sources via eight different pathways is presented. Based on the modelling results, source areas of high P-emissions can be localised and management options proposed.

Der Modellverbund AGRUM als Instrument zum landesweiten Nährstoffmanagement in Niedersachsen

Seit dem Jahr 2000 bestehen in der Europaischen Union durch die Wasserrahmenrichtlinie Wasserqualitatsziele fur Grundwasser sowie Oberflachen- und Kustengewasser. Fur Niedersachsen wurden alle relevanten diffusen und punktuellen Nahrstoffeintrage, -frachten und der erforderliche Reduktionsbedarf mit dem AGRUM-Modellverbund, bestehend aus dem Agrarsektormodell RAUMIS, dem Modellsystem GROWA/WEKU/DENUZ/MEPHOS sowie dem Nahrstofftransportmodell MONERIS, abgebildet. Aufbauend auf dem Basisjahr 2007 wurde die Eintragssituation 2021 simuliert. Berucksichtigt wurden unter anderem die Dungevorordnung (DuV 2006) sowie die Agrarumweltprogramme 2007 bis 2013, die weitere Entwicklung der Agrarmarkte und der Agrarpolitik. Die Ergebnisse zeigen, dass unter Berucksichtigung der bisherigen Masnahmen die Wasserqualitatsziele in Niedersachsen bis 2021 nicht flachendeckend erreicht werden. Als erganzende Masnahmen zeigen Agrarumweltmasnahmen, die auf eine Reduktion der Stickstoffbilanzuberschusse zur Verbesserung der Wasserqualitat abzielen, in einigen Regionen gute Reduktionspotenziale. In anderen Regionen ware eine Ausweitung auf die gesamte landwirtschaftliche Flache jedoch nicht ausreichend, um die Qualitatsziele zu erreichen. Insbesondere in diesen Regionen ist aufgrund einer intensiven landwirtschaftlichen Produktion, hoher Produktionserlose und des Flachennutzungsdrucks eine Zunahme der bisherigen Forderflachen nicht realistisch. Es mussen daher weitere Handlungsoptionen in Betracht gezogen werden, um die gesetzten Ziele zu erreichen.

National inventory of artificially drained lands in germany

With regard to the creation of river basin plans and programmes of measures according to the EU-Water Framework Directive, the importance of model-supported analyses of nutrient inputs into aquatic systems and the localization of source areas is increasing. Especially in lowland regions artificial drainage installations play a major role, but little information exists about their location within larger river basins. Therefore, artificially drained lands were identified by interpreting aerial photographs and typical site conditions of the drained plots were derived. Then, a GIS-based approach was developed, which allows the delineation of artificially drained lands by combining various site conditions like soil properties and land use type. The approach has been applied to Germany (357000 km²) and validity has been checked with small-scale drainage installation maps.