Evaluation of the SWAT model as an integrated management tool in the Švihov drinking water supply catchment

Švihov dam, the largest drinking water source in the Czech Republic and Central Europe, has problems with eutrophication. The Švihov dam catchment spreads over 1200 km2 and supplies over 1.5 million people in the capital of Prague and the Central Bohemian region with drinking water. Due to intensive agricultural activities and a lack of wastewater treatment plants in small settlements, the water quality is deteriorating. As a result, corrective measures need to be taken. Technological Agency of the Czech Republic supported this research which proposes different scenarios for a reduction of water quality degradation in the dam. The Trnávka dam watershed was chosen for study purposes as it occupies one quarter of the Švihov dam watershed. Hydrological balance was established using measured data. Point and non-point sources of nutrients were determined by field research and included in a Soil and Water Assessment Tool (SWAT) model. This study aims to propose complex watershed management to improve the state of the environment in the entire area and to reduce eutrophication. Different management practices would reduce nutrient loads of streams and increase water quality which is the critical factor in dam eutrophication. This research brings methodology and systematic approach to integrated management, and can be applied not only for the Švihov dam, but also for other watersheds, including those which function as drinking water supply.