A nitrogen model for European catchments: INCA, new model structure and equations

摘要

Anew version of the Integrated Nitrogen in Catchments model (INCA) was developedand tested using flow and streamwater nitrate concentration data collected fromthe River Kennet during 1998. INCA is a process-based model of the nitrogencycle in the plant/soil and in-stream systems. The model simulates the nitrogenexport from different land-use types within a river system, and the in-streamnitrate and ammonium concentrations at a daily time-step. The structure of thenew version differs from the original, in that soil-water retention volumes havebeen added and the interface adapted to permit multiple crop and vegetationgrowth periods and fertiliser applications. The process equations are nowwritten in terms of loads rather than concentrations allowing a more robusttracking of mass conservation when using numerical integration. The new versionis able to reproduce the seasonal dynamics observed in the streamwater nitrogenconcentration data, and the loads associated with plant/soil system nitrogenprocesses reported in the literature. As such, the model results suggest thatthe new structure is appropriate for the simulation of nitrogen in the RiverKennet and an improvement on the original model. The utility of the INCA modelis discussed in terms of improving scientific understanding and catchmentmanagement. style="line-height: 20px;">Keywords: modelling, water quality, nitrogen, nitrate, River Kennet, River Thames