(Dept. 1) Ecohydrology and Biogeochemistry
The interactions within and between green water (in terrestrial systems) and blue water (lakes, rivers, and subsurface aquifers) affect in complex ways the habitats for organisms and the reactive transport of abiotic components. Aquatic and terrestrial systems are coupled at multiple spatio-temporal scales. The overall goal of the Department of Ecohydrology and Biogeochemistry is to understand the ecohydrological and biogeochemical processes of these connected land- and waterscapes in natural, rural and urban environments. Therefore, our research projects focus on the following core topics:
- Interactions of landscape-freshwater ecosystems
- Physical and biogeochemical drivers under global change
- Water security in disturbed and urban systems
In our research, we integrate different modelling approaches with data collected in field studies, in large-scale manipulation studies, by long-term monitoring and in laboratory experiments. We study ecohydrological and biogeochemical processes using a variety of tracer techniques, particularly stable isotopes, and by measuring naturally dissolved solutes, conservative geogenic ions, trace organic matter, and nutrients. In doing so, we combine basic research with application aspects and aim to record and model the effects of climate and land use changes. With its laboratory infrastructure and expertise in the fields of inorganic and organic analysis as well as isotope measurement, the department performs a central function for the entire institute. To achieve our research goal, we combine our professional expertise from the research disciplines of hydrology, geochemistry, aquatic physics, ecology, environmental engineering, and geography.
Organizational principles of hyporheic exchange flow and biogeochemical cycling in river networks across scales
Understanding organizational principles of hyporheic exchange flow and biogeochemical cycling in landscapes is key for generalizing process knowledge.
At its deepest point, Lake Burgsee has one of the highest methane concentrations ever measured in a natural freshwater lake.
Based on the modelling of nutrient fluxes in the Danube River Basin, the authors estimated the (potential) contribution of the large floodplains to remove nitrate from the Danube and major tributaries. The active floodplains retain 33000 tons per year, or 6.5% of the total nitrogen emissions, which can be increased by 5000 tons if floodplains and water bodies are reconnected.
A hybrid empirical and parametric approach for managing ecosystem complexity: water quality in Lake Geneva under nonstationary futures
A hybrid model which combines a classical 1D lake model with data-driven machine learning was used to predict changes in deepwater oxygen concentrations under varying climatic conditions and nutrient concentrations. The model predicted deepwater oxygen concentrations of Lake Geneva more precisely than a classical approach. Increasing air temperatures have similar effects as phosphorus inputs.
Xylem water in riparian Willow trees (Salix alba) reveals shallow sources of root water uptake by in-situ monitoring of stable water isotopes
The authors monitored stable isotopes in-situ at high resolution in soil and plant water at an urban green space to understand the ecohydrological functioning of the Critical Zone, i.e., the thin, dynamic, life-sustaining skin of the Earth that extends from the canopy top to the active groundwater. At the end of the growing season deeper than upper soil water was used for plant water uptake.