Abstract: Synthesis of work at River Vltava catchment
Using a model chain comprising a hydrological model, catchment-scale model for phosphorus and nitrogen biogeochemistry and a lake stratification and aquatic ecosystem model we quantified nutrient sources and water quality in a large central European catchment (the upper River Vltava in the southern Czech Republic) from 1960–2010. The model chain was then employed to analyse the impacts of future climate change and various potential trends in socio-economic development in the catchment on nutrient status and eutrophication of surface waters and also to suggest cost-optimum measures for achieving compliance of with the EU Water Framework Directive (WFD) standards for good ecological status.
The climate change predicted for the period 2031-2060 with data from three regional climate models of different sensitivity to CO2 emissions showed well discernible effects on seasonal patterns of river flow and nutrient concentrations in stream and lakes. However, climate change impacts were low when compared to the much greater influence of human activity in the catchment. The best cost-effective set of mitigation measures to decrease phosphorus concentrations below the WFD standards included a high-efficiency P removal at most wastewater treatment plants combined with phosphorus-balanced fish production in fishponds and reduction of P losses from agricultural areas. However, following consultations with major stakeholders of the catchment, these mitigation measures were shown to be problematic due to their high costs and inconsistencies in the national legislation in the water management and surface water quality regulations.