A semi-distributed integrated flow and nitrogen model for multiple source assessment in catchments (INCA): Part II — application to large river basins in south Wales and eastern England

The integrated nitrogen in catchments (INCA) model is applied to two large river basins, the River Tywi in south Wales and the Great Ouse in eastern England. These two catchments have contrasting hydrogeology, land use and climatic regimes and provide an interesting test of the INCA model. The model is calibrated and validated against hydrological and chemical data for the rivers and a sensitivity analysis used to investigate parametric uncertainty. The annual loads estimated by the model are also compared with experimental data taken from nitrogen experiments around the world. Finally, scenario analysis is used to investigate impacts of changes in nitrogen deposition patterns and land use change in upland and lowland river systems.