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Modellierung und Prognose von Nährstoffeinträgen (Stickstoff und Phosphor) ins Grundwasser und in Oberflächengewässer

The fundamental objective of the European Union-Water Framework Directive (EU-WFD, European Parliament and Council of the European Union 2000) is to attain a good status of water resources in the member states of the EU by 2015. The environmental targets for qualitative status of groundwater bodies are specified in the Groundwater Directive (European Parliament and Council of the European Union 2006). Following the time table of implementing the EU WFD, EU member States carried out a review about the qualitative and quantitative status for all river basins in the EU. For river basins, whose good status can not be guaranteed by 2015, catchment-wide uniform operational plans and measurement programs have been drafted.

In Germany, the achievement of the good qualitative status is unclear, or rather unlikely for a number of groundwater bodies and surface waters due to nutrient inputs from diffuse and point sources. Most of all nutrient losses from agriculturally used land have been identified as the main reasons for exceeding the required quality standards, e.g. for nitrate (50 mg NO3/l). For this reason it is evident that implementation of catchment wide measurement programs have to include measures against nutrient pollution.

For large river basins like the Weser basin (ca. 49.000 km2) or on the Federal State level like for instance North Rhine - Westphalia (ca. 34.000 km2) the achievement of good qualitative status of groundwater bodies entails a particular challenge as the complex and regionally varying pedological, hydrological and hydrogeological relationships have to be considered simultaneously.

For this purpose we have developed simulation models, i.e. the reactive N-transport models GROWA-DENUZ/WEKU (Kunkel & Wendland, 2006; 1997) and the P-transport model MEPhos (Tetzlaff 2006). The models display a high spatial resolution (e.g. 100 x 100 m² and even higher), so that the specific site conditions in the study regions are considered adequately. The models GROWA-DENUZ/WEKU and MePhos account for the following nutrient input pathways and nutrient sources:

 

  • Input pathways for nitrogen originating from diffuse sources (agriculture, atmosphere):

    • Into groundwater
    • Into surface waters via direct runoff (separated into natural interflow und drainage runoff)
    • Into surface waters via groundwater runoff

       

  • Input pathways for phosphorous originating from diffuse sources:

    • Into surface waters via drainage runoff,
    • Into surface waters via groundwater runoff, Abfluss,
    • Into surface waters via wash-off,
    • Into surface waters via erosion.

       

  • Nitrogen and phosphorous inputs from point sources are additionally considered in the models, i.e. the inputs via:

    • Separate sewer systems,
    • Municipal wastewater treatment plants,
    • Industrial direct dischargers
    • Strom water overflow discharges.

  

Coupled to agro-economic model approaches (e.g. RAUMIS) the models GROWA-DENUZ/WEKU and MePhos are at present applied in a number of research projects in order to:

  • Analyse the actual nitrogen and phosphorous pollution loads in river basins and at the Federal State scale
  • Identify "hot spot" areas for the introduction of nutrient reduction measures
  • Determine nutrient reduction levels necessary to reach quality targets for groundwater and surface waters
  • Predict the impact of concrete reduction measures in a high spatial resolution.

 

 

Application of GROWA-DENUZ/WEKU-MePHos
in Germany (since 2008)

PeriodFunding InstitutionResearch topic
2008 - 2010NRW (LANUV)Modeling N and P inputs into groundwater and surface waters in NRW
2008 - 2009 Niedersachsen (NLWKN)N inputs into surface waters from diffuse and point sources in Lower Saxony (WAGRICO II)
2006 - 2009 Wesereinzugsgebiet (FGG Weser)Nutrient reduction measures on the water quality of groundwater and surface water in the Weser river basin (AGRUM)
2008 - 2010 Hessen (HLUG)Soil erosion atlas Hessen
2010 - 2012 Sachsen - Anhalt (LHW) Statewide modeling of nutrient inputs (N and P) into surface waters and groundwater in Sachsen - Anhalt
2010 - 2013 Mecklenburg - Vorpommern (LUNG) Statewide modeling of nutrient inputs (N and P) into surface waters and groundwater in Mecklenburg - Vorpommern
2010 - 2013 Schleswig - Holstein (LLUR)Statewide modeling of nutrient inputs (N and P) into surface waters and groundwater in Schleswig - Holstein

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