Research Theme A focuses on the upper boundary of terrestrial hydrosystems.
The goal is to improve the identification and quantification of processes affecting fluxes in and out of soils and plants. At the soil-plant-atmosphere interface, strong gradients are expected to substantially modify mass flux signatures. In this context, the numerical modelling studies performed within the IRTG will strongly interact with ongoing laboratory and field studies.
Research Theme B covers reactive transport within and the biogeochemical zonation of catchments.
It includes model development and application, and will also strongly interact with experimental work in the field and in laboratories within companion projects. The latter is needed for process understanding, conceptualisation, and model calibration and validation.
Research Theme C aims at studying and evaluating major sources of uncertainty that affect coupled process-based catchment models.
As the prediction of water quality throughout the catchment is the ultimate goal of the IRTG, special techniques for uncertainty assessment need to be developed and/or adapted for large-scale models. Inversion and data assimilation techniques will be used for uncertainty reduction. Optimal monitoring is of particular importance for increasingly data-hungry, complex, and less parsimonious process-based models.
Research Theme D focuses on the evolution of catchments over larger time spans.
This includes the simulation of the adaptation of vegetation to the hydrological regime, the change of landscapes due to physical erosion and deposition, and chemical weathering. An improved understanding of catchment evolution also helps characterising existing architectural patterns of landscapes that control present hydrology and thus helps to reduce parameter uncertainty.