Currently, climate change is considered as an important factor affecting nutrient loads introduced through riverine systems into the Baltic Sea. Although the prospect of a large increase in pollution has long seemed very real, it still does not translate into planning of effective remedial actions. One of the factors limiting the development of such activities is the scale of simulations, focusing generally on catchment outlet profiles. To fill this gap and enable a step forward in understanding responses towards future predictions in a higher resolution scale (subcatchment), we assessed nutrient load contribution using calculation profiles localised along a main watercourse and its tributaries. To track spatial and seasonal changes of total nitrogen and phosphorus under short- and long-term (RCP4.5 and RCP8.5) climate change scenarios we used the digital platform Macromodel DNS/SWAT. Having at our disposal a catchment model with a good performance we could follow not only total load changes in particular subcatchments, but also track localisation of the pollution sources and their direct impact on load estimations. Our results showed an increase of the loads, especially from the agricultural landuse type, up to 34% for TN and 85% for TP in the most extreme scenario. Moreover, forest areas have been noted as highly reactive to the climate changes, and through their localisation able to distinctly alter nutrient outflow. Finally, the contribution of urban areas should be further investigated since the dynamics of nitrogen and phosphorus release from impervious surfaces is noticeably different here than from the other diffuse sources.

Transport of sediment particles from the source of their origin to a deposition area is of utmost importance, especially in catchments very prone to erosion. Especially, since future climate changes are predicted to enhance severity of the sediment transport issues, particularly in catchments with dammed reservoirs, which capacity and water quality can be extremely altered. In the current study we tracked, with a monthly step, two mineral and one mineral/organic sediment fraction delivered from the Carpathian Mts. catchment (Raba River) to the drinking water reservoir (Dobczyce). This was possible by combining SWAT and AdH/PTM models on the digital platform - Macromodel DNS. Moreover, we have applied a variant scenario analysis including RCP 4.5 and 8.5, and land use change forecasts. The results highlighted the differences between the two analyzed hydrological units and showed large variability of the sediment load between months. The predicted climate changes will cause a significant increase of mineral fraction loads (silt and clay) during months with high flows. Due to the location and natural arrangement of the reservoir, silt particles will mainly affect faster loss of the first two reservoir zones capacities, which is consistent with their intended use as traps for larger fractions. The increased mobility of the finer particles (clay) in the reservoir may be more problematic in the future. Mainly due to their binding pollutant properties, and the possible negative impact on drinking water abstraction from the last reservoir zone.