Spatial and Temporal Changes in Nutrient Source Contribution in a
Lowland Catchment within the Baltic Sea Region under Climate Change
Scenarios
Abstract
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.