Finnish coastal nutrient load model
The browser-based FICOS model (Finnish Coastal Nutrient Load Model), partially developed at Finnish Environment Institute, helps researchers and authorities in planning, evaluating, and monitoring water management measures. With the FICOS model, it is easy to calculate and compare the effects of load changes on coastal water quality. The model covers the entire Finnish coast up to the economic zone, with some exceptions.
FICOS is a sum of many models
In the FICOS total load model, the load from catchment areas and external marine areas combines with point sources in the marine area, internal loading, and atmospheric loading, which are transported by currents. The user can select the desired modelling resolution through the interface according to the water body division of the Water Framework Directive and the internal resolution of the marine model – one or ¼ nautical mile depending on the area. Point loads can be modified through the interface, and different runs can also be compared with each other. This allows, for example, the examination of the effects of a new polluter on the water quality of the coastal area in the upper 10 meters (surface layer) and the water below it (bottom layer). Even more versatile impacts on loads and model operation can be achieved by using it directly bypassing the interface. The model produces concentrations of total nitrogen and phosphorus, as well as dissolved inorganic nitrogen and phosphorus in both layers, and the concentration of chlorophyll-a and biomass for cyanobacteria and other algae in the surface layer. Results can be viewed directly in the interface or exported for further processing, for example, in a spreadsheet program.
FICOS uses nutrient loads, water flow and temperature data, and solar radiation amounts as inputs. Catchment area load is calculated with the Vemala model. The catchment area load is combined with point sources in the coastal area, atmospheric load, internal load, and external load from the open sea. Currents, water temperature, and salinity have been pre-modeled with an accuracy of up to a quarter nautical mile (about 460 meters) depending on the coastal area, using either the COHERENS or NEMO flow model. The model uses measured load data as input and currently covers the years 2006—2020.
Goal of replicability and modifiability
The model system is designed to be easily modifiable and expandable, and its different parts can even be located on different servers. Sub-models, interfaces, and the user interface can be modified independently of each other, and the model can be replicated to other coastal areas. However, the modeling system requires a lot of computing power, so it is not yet suitable for direct use by the general public.
The modelling tool has been developed through the collaboration of many parties. Syke, the Finnish Meteorological Institute, Åbo Akademi, ELY Centers, and the University of Helsinki have been involved in the work. The main financier and client of the project is the Ministry of the Environment. Significant assistance was also received from the Royal Institute of Technology (KTH) in Sweden during the startup phase. The model has been used in many studies and research projects. The operation of the whole and its sub-models has also been presented to the research community and evaluated in scientific publications.
Scientific articles
- Lignell, R., Miettunen, E., Kuosa, H., Ropponen, J., Tuomi, L., Puttonen, I., Lukkari, K., Korppoo, M., Huttunen, M., Kaurila, K., Vanhatalo, J., and Thingstad, F. 2025. Modeling how eutrophication in northern Baltic coastal zone is driven by new nutrient inputs, internal loading, and 3D hydrodynamics. Journal of Marine Systems, 249: 104049. https://doi.org/10.1016/j.jmarsys.2025.104049 (sciencedirect.com)
- Hyytiäinen, K., I. Huttunen, N. Kotamäki, et al. 2024. Good eutrophication status is a challenging goal for coastal waters. Ambio 53, 579–591. (sciencedirect.com)
- Puttonen, I., K. Lukkari, E. Miettunen, J. Ropponen, and L. Tuomi. 2024. Estimating internal phosphorus loading for a water quality model using chemical characterisation of sediment phosphorus and contrasting oxygen conditions. Science of the Total Environment 942 173717. (sciencedirect.com)
- Tuomi, L., E. Miettunen, P. Alenius, and K. Myrberg. 2018. Evaluating hydrography, circulation and transport in a coastal archipelago using a high-resolution 3D hydrodynamic model. Journal of Marine Systems 180: 24-36. https://doi.org/10.1016/j.jmarsys.2017.12.006 (sciencedirect.com)
- Huttunen, I., M. Huttunen, V. Piirainen, M. Korppoo, A. Lepistö, A. Räike, S. Tattari, and B. Vehviläinen. 2016. A National-Scale Nutrient Loading Model for Finnish Watersheds─VEMALA. Environmental Modeling & Assessment 21:83-109. (link.springer.com)
More Information
Senior Researcher, Jonna Piiparinen, Finnish Environment Institute (Syke), firstname.lastname@syke.fi