Changes in Runoff and Nutrient Removal by Small Tributaries of the Gulf of Finland as a Result of Possible Regional Climate Change

Using the methods of mathematical modeling, changes in runoff and a related removal of nutrients from three small tributaries of the Gulf of Finland as a result of possible regional climate change in the 21st century are projected. The RCP 2.6 and RCP 8.5 are considered as climatic scenarios: these are the best and the worst scenarios in terms of environmental forcing, respectively. It is shown that the RCP 8.5 will lead to an increase in river runoff by not more than 25% relative to 2006–2015. The RCP 2.6 will result in a 6% reduction in runoff. Real climate changes are likely to follow an intermediate scenario. Consequently, the projection of the climate change consequences will be in the interval between the resulting extreme estimates, and extreme changes in the hydrological regime of the catchments of small rivers and corresponding changes in the nutrient removal should not be expected in the region under consideration.