- The INCA approach has been very good in producing a user friendly and widely available piece of software dealing with nitrogen impacts in catchments. The bringing together of field workers, hydrobiogeochemists and modellers has been a good and challenging one with "cross peer reviewing" (Colin Neal, pers. comm.).
- While seasonal trends in nitrate concentrations was well represented by INCA simulations, extremely high flows and associated intermittent high nitrate concentrations were often poorly simulated. This problem is likely to remain for a deterministic model as INCA.
- The impacts of the nutrients on the aquatic environment are linked to biological functioning in a connected fashion and there is a major need for an integrated (nitrogen (N), phosphorus (P), silicon (Si))-INCA model to examine their relative importance and potential nutrient limitation.
- The absence of biological processes within the river stream as in the INCA model makes it difficult to apply in case of slow-flowing lowland eutrophic rivers where the role played by plant uptake may become significant.
- The RIVERSTRAHLER model is one of the few available tools for modelling nutrient cycling and ecological functioning of entire drainage networks as a function of the properties of their watershed.
- The successful RIVERSTRAHLER application to the Seine (Billen & Garnier, 2000, Billen et al., 2001) has proven the suitability of this modelling approach for management issues. The
- Danube-RIVERSTRAHLER application requires additional input data for further validation of the model.
- The pragmatic approach used in the RANR project highlights potential solutions for areas where input data are scarcely distributed.
- Most of the models investigated here have been developed for temperate climate zones and may not be directly suitable for extremely dry climates.
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