Norwegian Institute for Air Research
Netherlands Institute for Ecology
Tyndall Centre for Climate Change Research
Institute for Environmental Studies, Free University Amsterdam
University of Plymouth
Centre for Social and Economic Research on the Global Environment
Land-Ocean Interactions in the Coastal Zone
 


Nutrient Dynamics in European Water Systems
Synthesis Results

2. Characterisation of nutrient sources (3 of 4)

 
2.2 Riverine and groundwater nutrient inputs
 

The INCA project (Neal et al., 2002) has developed a generic deterministic model (INCA) that includes land and river processes, and is driven by spatially explicit input data. The model accounts for stocks of ammonium and nitrate in the soil, in groundwater pools and in stream reaches. Figure 2.2(a) illustrates the land and river processes in the INCA model.

One of the valuable functions of INCA is its ability to be used as a management tool, allowing predictions on the effects of changing policies (Jarvie et al., 2002).

Wade et al. (2002) have developed INCA-P; a version of the model for phosphorus. Linking INCA-P with INCA could provide a more complete assessment of the combined impacts of N and P in river systems.
 
Figure 2.2(a). Overview of land and instream processes in the INCA model from Wade et al. (2002)
Figure 2.2(a). Overview of land and instream processes in the INCA model (Wade et al., 2002).
 

The RIVERSTRAHLER (Billen & Garnier, 2000 and Garnier et al., 2002) model from the EROS-21 project synthesises the hydrological network of a river basin by stream order (HYDROSTRAHLER module). This reduces the computational load to a reasonable level. For different sub-basins, nutrient and organic inputs are derived from gross statistics (population density, type and intensity of industrial activity, fertiliser application, land use) (Figure 2.2(b)).

The application of the RIVERSTRAHLER model to the Seine river system allowed quantification of the overall retention of nitrogen by riparian wetlands (Billen & Garnier, 2000). It was shown that 25-55% of the nitrogen coming from below the root zone of agricultural land or from aquifers was retained or eliminated before reaching surface water. The lower retention was found in areas where dense agricultural draining had been installed, thus by-passing riparian wetlands.

Figure 2.2(b). Relationship between specific fluxes of nitrogen and phosphorus and population density. Rivers: Da=Danube, EL=Elbe, Lo=Loire, Mo=Mosel, Rh=Rhine, Sch=Scheldt, Se=Seine (Garnier et al., 2002).
Figure 2.2(b). Relationship between specific fluxes of nitrogen and phosphorus and population density. Rivers: Da=Danube, EL=Elbe, Lo=Loire, Mo=Mosel, Rh=Rhine, Sch=Scheldt, Se=Seine (Garnier et al., 2002).
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