The hyporheic zone describes the interface between ground and surface waters. It plays a significant role in the ecology of streams and their self-cleaning potential. In this project, we investigate the hypothesis that changing climatic drivers significantly endanger the function of the hyporheic zone. Increased temperature leads to increased respiration and formation of oxygen-free areas, and accelerated deposition of fine sediment. Under conditions of stream low water levels (with high proportion of groundwater) reduced substances enter the upper parts of the hyporheic zone and surface water. The contact with atmospheric oxygen leads to formation of areas of preferential oxidation of reduced substances (iron clogging, nitrification).
In this project the effect of climate stressors (fine sediment loading, temperature and discharge regimes) on the N and Fe cycles will be investigated in field experiments on selected streams. To quantify the groundwater exchange flux at various locations the natural tracer radon is used. These measurements will be combined with temperature and geochemical profile measurements in cooperation with other research groups with the aim of identifying the groundwater inflow and outflow areas and thus inferring the spatial and temporal heterogeneity on the scale of a river section.