Marine application of the Danish EPA’s Marine Model Complex and Development of a Method Applicable for the River Basin Management Plans 2021-2027. Improved growth conditions in selected estuaries based on 30% reductions in land based nutrient loads.

Paula Canal-Vergés, Anders Erichsen, Mikkel Keller Lees, Karen Timmermann, Mogens Flindt

Research output: Book/reportReportCommissioned

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Abstract

When preparing the Danish River Basin Management Plans 2015-2021 (RMBP 2015-2021),
DHI and Aarhus University (AU) developed a number of mechanistic (DHI) and statistical (AU)
models that were used for calculating chlorophyll-a target values defining the threshold (GM)
between ‘Good Ecological Status’ (GES) and ‘Moderate Ecological Status’. The models were
also used for calculating Maximum Allowable Inputs (MAIs) of total nitrogen (N) from Danish
catchments based on chlorophyll-a threshold values and a proxy for eelgrass depth limit. Hence,
the development aimed at both the model development and the development of a method for
calculating the MAIs.
As part of the political, regulatory package ‘The Food and Agriculture Package from 2015’ an
international evaluation of the procedures used in the RBMP 2015-2021 was conducted. The
evaluation was finalised autumn 2017 with a report (Herman et al. 2017) including a number of
recommendations for improving the scientific background behind the RBMP 2021-2027.
To follow up on the international evaluation, the Danish EPA facilitated a range of R&D projects
with the overall aim to develop methods to calculate robust, transparent and differentiated
chlorophyll-a reference values (and corresponding target values) and MAIs in as many water
bodies as possible for incorporation into the RBMP 2021-2027.
Two central R&D projects relate to the continued model development in the assessment of
reference chlorophyll-a values (and corresponding target values) and final MAI calculations.
Other projects also support different aspects of the final MAI calculations, but here we focus on
those two central R&D projects:
• ‘Recommendations for the continued development of models and methods for use in the
River Basin Management Plan 2021-2027. Follow-up on the international evaluation of
marine models behind the River Basin Management Plan 2015-2021’ (Erichsen &
Timmermann 2018)
• ‘Application of the Danish EPA’s Marine Model Complex and Development of a Method
Applicable for the River Basin Management Plans 2021-2027’.
The outcome of the above research projects is a set of MAIs based on a range of different
assumptions regarding future developments in nutrient loading from neighbouring countries and
the atmosphere as described in Erichsen et al. 2020. In the present technical note, the
assumptions and input data behind management scenario 1 and the corresponding results are
presented. In management scenario 1, it is assumed that all national and international adopted
treaties related to nutrient management, including BSAP (Baltic Sea Action Plan), RBMP 2015-
2021, OSPAR (Oslo/Paris convention (for the Protection of the Marine Environment of the
North-East Atlantic)), and the NEC-directive (National Emission Ceilings directive) have been
implemented.
Original languageEnglish
Number of pages49
Commissioning bodyMiljøministeriet
Publication statusPublished - 2021

Keywords

  • Danish EPA
  • River Basin Management Plans 2021-2027
  • Model complex

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