Water quality in watercourses with long-term changes in the hydrological regime

The PERUN project (SS02030040) is evaluating water quality data in selected watercourses with major changes in long-term hydrological characteristics. For the purpose of this paper, time series of basic physicochemical parameters will be evaluated, which at some monitoring sites start as early as the 1960s. The evolution of concentrations, their relationship to stream flows, and the objectives of good ecological status given by the Water Framework Directive will be assessed. Problem areas with significant discharges of wastewater and the occurrence of dry periods will be characterised, and the statistical significance of trends in concentrations of physico-chemical parameters will be tested at selected sites with long time series. The typical behaviour of these chemical substances will be described.