Assessment of future climate and land use changes on streamflow and phosphorus transport in a Swedish agricultural catchment

Sammanfattning

Despite efforts to reduce nutrient excess in surface waters in the last decades, eutrophication continues to be an important environmental problem in Europe. The presence of excess phosphorus (P) in waters, together with nitrogen (N), is one of its main causes. It is crucial to understand how P may respond to future environmental change to adopt adequate management strategies to fight this problem in the long term. The present study explored this direction of research by testing the effects of future climate, weather and land use on streamflow and total P using hydrologic and water quality modelling in Sävjaån catchment (722km2), central Sweden. The scenarios represented future changes in the period 2071-2100 derived from representative concentration pathway (RCP) emission scenarios, changes in extreme precipitation patterns and land use changes. Results showed higher maximum P loads when more extreme precipitation events were combined with high emission scenarios (RCP 4.5 and 8.5). Besides, extreme precipitation increase caused significant differences between maximum and minimum annual P loads, suggesting an increased uncertainty in future projections. Lastly, results indicated a shift in the seasonal distribution in loads, with decreases in winter and spring loads associated with less snowfall and increases in autumn and especially summer loads.