Modelling impacts of land use change and climate change on nitrate-nitrogen in the River Don, North East Scotland

The river quality model QUASAR (Quality Simulation Along Rivers) has been applied to the River Don system in North East Scotland. This mass balance model for nitrogen has been used to estimate the impacts of land use change and climate change on river water quality. Changing agricultural patterns have been simulated and indicate increased nitrogen levels in the river as catchment land use changes. Climate change will alter flow regimes, temperature and nitrogen mineralization patterns. Simulation runs for a range of scenarios illustrate the impacts of climate change with the most significant effect being mineralization of nitrogen in the soil feeding through into the river system. These higher nitrogen levels are reduced slightly by the increased temperatures and decreased summer flows, both of which enhance denitrification processes.