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This study focuses on changes of biogeochemical parameters related to variable rainfall-runoff conditions and to land cover types for eight headwater catchments in Central Europe. Linear regression, Spearman rank correlation, principal component analysis and C/Q (concentration – discharge) hysteresis loops revealed the main relationships. The presence of peatbogs and waterlogged spruce forests had a decisive influence on the biogeochemistry (COD = chemical oxygen demand measured using the permanganate methodMn, humins, Fe, P-PO43− TP = total phosphorus, N-NO3−). The strongest positive correlation of organic matter and Fe is represented in a catchment with the largest area of damaged forest (70%), but with a smaller proportion of waterlogged areas (8%). High flow rates influence greater release of organic matter and N-NO3−. The catchment with the highest (80%) peatbog cover and the catchment that had undergone revitalization showed similar behaviour in terms of water biogeochemistry. The type of rainfall-runoff event affected the velocity of pH changes, whereas the variability in electric conductivity was also controlled by the catchment characteristics and hydrological preconditions. [ABSTRACT FROM AUTHOR]

• Pan evaporation has been rapidly growing in the Czech Republic since 1990. • The mean evaporation between 2001 and 2018 was 18% higher than the 1971–2000 average. • Future projections suggest a further increase in evaporation by up to 54%. • Increased evaporation has already enhanced the severity of recent droughts. Evaporation from open water surfaces is often estimated based on the pan evaporation (E pan), which is an essential measure for estimating atmospheric evaporative demand. Within the Central European region, E pan appears to be slightly underestimated in the case of the hydrological balance of water bodies. In the context of the recent multi-year period of drought, significant losses of surface water deposits were observed in countries of Central Europe. In spite of the 'evaporation paradox' phenomenon, E pan is not generally decreasing as expected by many studies from past decades. Recorded observations from the Czech Republic show an increase in E pan , which is associated with an increase in global radiation and vapor pressure deficit. The vast majority of meteorological stations show a strong or very strong increase in E pan during April, June, July and August. During the 1971–2018 period, the annual mean E pan has been increasing by an average of 2.97 mm yr−1. For the period 2001–2018, the mean E pan was 18% higher (519 mm) than the 1971–2000 average (440 mm). Our simulations of future scenarios, using regional climate models, predicted a growth in E pan of up to 27–54%. Such an increase in evaporation would cause serious consequences for surface water availability and agricultural production during the periods of drought in the Czech Republic, as the drought period 2014–2018 has clearly demonstrated. [ABSTRACT FROM AUTHOR]