Modelling the effects of land use and climate change on the water resources in the eastern Baltic Sea region using the SWAT model

Abstract Combined and separate impact of climate and land use change on the future river runoff was assessed in the eastern Baltic Sea region by using the SWAT (The Soil and Water Assessment Tool) hydrological model. SWAT was applied to assess how plausible changes in climate and land use may affect the river hydrology by the end of the century. The model was calibrated and validated for a period from 1970 to 2010 (41 years) using daily river runoff data. Statistical and visual analysis of the achieved model presented adequate fit to the observed data allowing the reproduction of the current hydrological conditions of the basins for future analysis. The following conclusions from the study were made: 1) a strong linear correlation between forest cover change and annual river flow change was found; 2) the impact of land use change on runoff is important on an annual scale; 3) the scale of a basin is not important on the hydrological response to forest cover change; 4) the combined effect of land use and climate change was found to be non-additive. Findings of this study would help policy makers, to improve land and water management decisions and in formulating strategies to harness the positive impacts of possible overall increase in river runoff in the north-eastern Baltic Sea region.