The INCA model was developed over 20 years as part of several EU funded projects, among which EU- INCA, Eurolimpacs, REFRESH and, more recently, MARS. Other projects funded by agencies in the UK, Canada, Norway, Finland and Sweden have also contributed to its development.

INCA is a processed based dynamic model representation of plant/soil system dynamics and instream biogeochemical and hydrological dynamics. The INCA model has been used to assess a wide range of environmental change issues in catchments including land use change, climate change and changing pollution environments including point and diffuse pollution. The model has been applied to a wide range of key European ecosystems.



Across the European Union there are concerns about a wide range of pollutants that affect water resource systems as well as environmental change such as land use change and climate change. With the EU Cap and Farming reforms there has been changing agriculture and land use, and this will continue into the future. As the Water Framework Directive drives new policies, and as climate change is altering hydrological regimes and temperatures, there is increasing need for tools able to predict how these factors will affect water resources, river ecology, agriculture, terrestrial ecosystems and land use. For example, nitrogen (N) and phosphorus (P) in lowland and upland fresh water systems can cause eutrophication, leading to rapid aquatic plant growth. Such increases in growth are often viewed as a nuisance as certain plant species may grow at the expense of others and, within freshwaters, the microbial breakdown of the dead plant matter can lower oxygen levels which is detrimental to invertebrate and fish populations. The problems of freshwater eutrophication are usually associated with lowland, intensively farmed areas where fertilizers provide a significant source of N and P and/or urban areas where domestic and industrial effluent is discharged to the receiving watercourse and groundwater.

Whilst management strategies have been implemented to control N and P in river systems, these have tended to address single issues: either diffuse or point sources, or upland or lowland areas. For example, the N concentrations and loads in rivers reflect the integration of the catchment N sources: fertiliser inputs, atmospheric deposition and sewage discharges. Superimposed on these anthropogenic inputs are contributions from the vegetation and mineralisation (and subsequent nitrification) of organic N in soils. Furthermore, the combination of the multiple catchment N sources has a downstream effect, influencing the options for further water utilization and impacting the water quality of estuarine and marine areas. Thus, given the holistic nature of the N problem, an integrated management approach is required.

The INCA suite of models has been developed to support such an integrated approach.

A great many INCA partnerships have been established so far. The map shows the key partners established across Europe as part of the Eurolimpacs project. Other users outside Europe include partners in Brazil, Australia, Canada, the USA and China.


INCA design

The INCA model has been designed to investigate the fate and distribution of chemicals in the aquatic and terrestrial environment. The model simulates flow and water quality and tracks the flow paths operating in both the land phase and riverine phase. The model is dynamic in that the day-to-day variations in flow and water quality can be investigated following a change in input conditions form point or diffuse sources such as atmospheric deposition, sewage discharges or fertilizer addition. The model can also be used to investigate a change in land use (e.g. moorland to forest or pasture to arable) or a change in climatic conditions. Dilution, natural decay and biochemical transformation processes are included in the model as well as the interactions with plant biomass such as nutrient uptake by vegetation on the land surface or macrophytes in streams.

INCA has been designed to be easy to use and fast, with excellent output graphics and a user-friendly user interface. The menu system allows the user to specify the semi-distributed nature of a river basin or catchment, to alter reach structure and lengths, rate coefficients, land use, velocity-flow relationships and to vary input loads.

INCA provides the following outputs:

-Daily time series of flows, water quality concentrations at selected sites along the river

- Profiles of flow or water quality along the river at selected times;

- Cumulative frequency distributions of flow and water quality at selected sites;

- Tables of statistics for all sites;

- Daily and annual pollution loads for all land uses and all processes.

How to get INCA

The INCA suite a model is delineated in various problem-specific versions. Those include:

INCA-Phosphorus, INCA-Nitrogen, INCA-Carbon, INCA-Sediment, INCA-Pathogens, INCA-Radionuclides, INCA-Mercury and INCA-Contaminants.

Since 2015, the distribution of INCA is managed by the Norwegian Institute for Water Research. In agreement with the INCA development consortium, NIVA will distribute here the most recent version of the INCA software; those version will be added progressively as this website is completed, starting January 2015 with INCA-Phosphorus. Please contact Luca Nizzetto, research scientist, for more information.

The software is available as a Windows executable, which can be executed either with the graphical-user interface or in batch mode. It can be obtained by filling the form specific to each INCA version using the links on the left.


The developers of the original version of INCA are Dan Butterfield, Martyn Futter (Swedish Agricultural University), Andy Wade (University of Reading), and Paul Whitehead (University of Oxford). The software is described in the following publications:

Wade, A.J., Durand, P., Beaujouan, V., Wessel, W.W., Raat, K.J., Whitehead, P.G., Butterfield, D., Rankinen, K. and Lepisto, A. (2002) A nitrogen model for European catchments: INCA, new model structure and equations, Hydrology and Earth System Sciences, 6, 559-582.

Whitehead, P.G., Wilson, E.J. and Butterfield, D. (1998) A semi-distributed Integrated Nitrogen Model for Multiple source assessment in Catchments (INCA): Part I - Model Structure and Process Equations. Science of the Total Environment, 210/211: 547-558.

Whitehead, P.G., Wilson, E.J., Butterfield, D. and Seed, K. (1998) A Semi-distributed Integrated Nitrogen Model for Multiple source assessment in Catchments (INCA): Part II Application to large River Basins in South Wales and Eastern England. Science of the Total Environment, 210/211: 559-583.

Last updated 02.02.2016