Modelling instream nitrogen variability in the Dee catchment, NE Scotland

The Integrated Nitrogen in CAtchments model (INCA) was applied to the River Dee, Aberdeenshire, NE Scotland. To a first approximation the model was ab le to simulate the annual mean streamwater NO3-N concentrations observed al ong the length of the main channel. This provided the basis for using INCA to subsequently explore the effects of N deposition and land use management on streamwater NO3-N concentrations and loads. On an annual timescale, the model predictions suggest that NO3-N concentrations will decrease by 5% fo llowing a 20% reduction in fertiliser application. Furthermore, model resul ts also suggest that a 50% increase in N deposition will cause a 15% increa se in the streamwater NO3-N concentrations. The utility of INCA as a tool f or catchment management is discussed, current limitations are highlighted a nd possible improvements are suggested. (C) 2001 Elsevier Science B.V. All rights reserved.