Predicting Nutrient Loads in Two European Catchments

Institute for Environment and Sustainability, Joint Research Centre of the European Commission, TP 460, I-21020 Ispra (VA), Italy. (e-mail: [email protected]) ABSTRACT The hydrological model SWAT was applied to two watersheds, the Ouse (North of UK) and the Vantaanjoki (South of Finland). The Ouse watershed is characterised by heavy husbandry and large application of organic nitrogen and phosphorus on pasture. The Vantaanjoki watershed is dominated by forest and barley. The model performance was evaluated comparing the measured and predicted time series for flow, total nitrogen and total phosphorus at the watershed outlets. The model performed well in predicting water and nutrient losses. The model showed a good sensitivity in predicted nutrient losses for both the agricultural and forested catchments. The model was then used to estimate the contribution of agriculture to the total load of measured nutrient at the outlet of the two river basins. It was highlighted that for a same catchment diffuse contribution to total nutrient load can be highly variable both in time and space.