Authors: Mikołaj Piniewski, Sirkka Tattari, Jari Koskiaho, Olle Olsson, Faruk Djodjic, Marek Giełczewski, Paweł Marcinkowski, Marta Ksiezniak, Tomasz Okruszko.
Riverine nutrient loads are among the major causes of eutrophication of the Baltic Sea. This study applied the Soil & Water Assessment Tool (SWAT) in three catchments ﬂowing to the Baltic Sea, namely Vantaanjoki (Finland), Fyrisån (Sweden), and Słupia (Poland), to simulate the effectiveness of nutrient control measures included in the EU’s Water Framework Directive River Basin Management Plans (RBMPs). Moreover, we identiﬁed similar, coastal, middle-sized catchments to which conclusions from this study could be applicable. The ﬁrst modelling scenario based on extrapolation of the existing trends affected the modelled nutrient loads by less than 5%. In the second scenario, measures included in RBMPs showed variable effectiveness, ranging from negligible for Słupia to 28% total P load reduction in Vantaanjoki. Adding spatially targeted measures to RBMPs (third scenario) would considerably improve their effectiveness in all three catchments for both total N and P, suggesting a need to adopt targeting more widely in the Baltic Sea countries.
The objectives of this paper are as follows: (1) Estimation of factors affecting nutrient loads for the purpose of modelling their changes in a 15-year perspective in three medium-sized catchments ﬂowing into the Baltic Sea; (2) Evaluation of the effectiveness of catchment-speciﬁc nutrient load control measures included in the existing RBMPs in a 15-year perspective; (3) Evaluation of how spatial targeting of measures could enhance the effective-ness of RBMPs in three case study catchments.