Model structure

MONERIS (MOdelling Nutrient Emissions in RIver Systems) is a semi-empirical, conceptual model for the quantification of nutrient emissions from point and diffuse sources in river catchments (BEHRENDT ET AL., 2000; 2002a; 2002b). MONERIS now has a new model surface programmed in C#, which we implemented in 2012, (previously EXCEL/VBA was used for all calculations). In MONERIS results are presented for total nitrogen (TN), total phosphorus (TP) and dissolved silicium (Si). Furthermore, a scenario manager has been developed to calculate the effects of measures on the nutrient emissions for different pathways and spatial units.

The model is based on data for runoff and water quality for the study area, along with a Geographical Information System (GIS), thus bringing together digital maps as well as statistical information for different administrative levels. The application of MONERIS allows regionally differentiated quantification of nutrient emissions into a river system on the level of an analytical unit. The results can be visualised in GIS generated maps.

Figure 1 gives an overview of the main pathways and processes in MONERIS. There are seven pathways for nutrient emission into surface waters:

  • point sources (from municipal waste water treatment plants and direct industrial discharge)
  • atmospheric deposition on water surface areas
  • groundwater
  • tile drainages
  • urban areas (sealed)
  • erosion
  • overland flow (dissolved nutrients
Whereas point emissions from waste water treatment plants and industrial sources are directly discharged into the rivers, diffuse emissions into surface waters come from different pathways, represented by separate flow components. The direct and diffuse components must be separated, since the underlying processes and the nutrient concentrations are different

The model facilitates beneath the calculations of emissions into surface waters, calculations of nutrient retention in surface waters, and allows a comparison between the calculated and the observed loads.
Fig.1: Pathways and processes for nutrient emission into surface waters  (Venohr et al., 2011).


The Model MONERIS is realised in C#, it is built up of the following parts.


    • MONERIS Preprocessing
Until you perform a nutrient modelling process in a new catchment, you must prepare the input data using the Preprocessing tool. It simplifies the preparation of the modelling process due to the supporting handling of input data by a Geographical Information System (GIS) and a direct connection to necessary calculation Databases.

    • MONERIS 3.0
This Data file contains source code, user interface, also the connection to necessary calculation Databases. MONERIS IN.mdb is the data base containing input data. All consistent and changeable data relating to each analytical unit are stored in it. It contains climatically, hydrology, administrative and project-meta-data. In MONERIS OUT.mdb calculation results and constants are stored.