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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]

Changes in the frequency, magnitude, and seasonality of hydrological extremes are one of the expected consequences of climate change. Recent years suggested an increasing risk of drought occurrence and restricted water supply even in usually humid mountain regions. Our research is focused on the evaluation of regional climate change and its effect on hydrological drought characteristics in headwater areas in the Ore Mountains along the Czech/German border. The main aim was to evaluate and compare streamflow regime changes and trends in long‐term hydrological and climatic time series within selected sub‐catchments of the Svatava (Zwota) River, the Rolava River, and the Načetínský Brook (Natzschung). A comparative statistical analysis for the 1967–2018 period was performed using various homogeneity and trend tests. Longer runoff time series with earlier beginnings were examined for two catchments as well. The results pointed to significant, continuous warming in the region which is accompanied by decreasing trends in snow cover depths in the colder half of the year. Drought indices based on runoff data were derived in the Indicators of Hydrologic Alterations (IHA 7.1) software environment. The seasonality of hydrological drought occurrence changed markedly after 1992, when most severe drought events started to concentrate between August and October in the study area. Increasing trends in deficit volumes were found in two catchments characterized by lower elevation. Furthermore, there was a significant decrease in average and minimum flows in spring and summer months in all catchments observed between 1967 and 2018 despite relatively stable amounts of precipitation and land cover. [ABSTRACT FROM AUTHOR]