Globally freshwater ecosystems are considered to be under severe threat from human pressure
and climate change (Vörösmarty et al. 2010). Malmqvist and Rundle (2002) suggest that running
water is the most impacted upon ecosystem on Earth due to being surrounded by dense human
settlements and exploited for domestic and industrial water supply irrigation electricity
generation and waste disposal. For example the progressive over-exploitation of surface water
resources for irrigation and urban uses in the Colorado River Basin has resulted most years in
no runoff reaching the river s delta (Gleick 2003). [ ] Hereafter natural and anthropogenic
driving forces will be referred to as global and regional driving forces respectively. The
future effects of these forces up to the 2050s will be assessed in quantitative scenarios
implemented in a hydrological model. It is believed that using this nomenclature (i.e. global
and regional instead of natural and anthropogenic) better reflects considered environmental
stressors since global-scale driving forces will include not only climatic change but also
changes in CO2 atmospheric carbon dioxide and plant physiological parameters whereas
regional-scale driving forces will include changes in land use agriculture development and
agricultural water management. Hence the difference is that the first group of driving forces
acts globally and independently on the study area whereas the second group includes factors
that are specific to the study area. Furthermore in order to expand on the title of this
thesis impacts in the present study will be assessed not only on the flow regime as such but
also on its ecological functions i.e. on the environmental flow regime. This is motivated
mainly by the semi-natural character of the study area that is unique in Poland and in Europe
but it also underlines the novelty of this thesis as going beyond the pure impacts on the flow
regime in a scenario-modelling framework is rare in hydrological science if achieved at all.
