Water age dynamics in a Mediterranean catchment and their ecohydrological implications in a changing environment

• Applicant: Dr. Matthias Sprenger
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2018 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 397306994

There is an urgent need to assess the relevant hydrological processes of Mediterranean mountain catchments and their potential altered functioning for the water supply due to land-use and climate changes. I will, therefore, study in collaboration with the host institution from the IDAEA-CSIC in Barcelona, how vegetation, soils and groundwater influence the catchment storage, mixing and release of water via runoff and evapotranspiration in the long-term research catchments in Vallcebre, Spain.The group of IDAEA-CSIC gathered hydrometric and stable isotope (d2H, d18O) data of the different hydrological catchment compartments, including the water of rainfall, throughfall, stemflow, stream, groundwater, soils and vegetation. I plan to use this extensive data set to apply recently proposed methods for travel time estimations to improve our understanding of the water flow and transport within the catchment. I will first test how Storage Selection functions (Rinaldo et al., 2015) can help to describe the highly time variable catchment water fluxes (runoff and evapotranspiration). Then, I aim to apply the new concepts of “young water fraction” (Kirchner, 2016) and “new water fraction” (Kirchner, 2017) to better describe the short-term component of the travel time distribution. These methods have not yet been tested for Mediterranean environments, but the extensive data set for the Vallcebre catchments allows accounting for current questions in catchment isotope hydrology: How can water age studies be improved by high rainfall-runoff sampling frequency and taking throughfall/stemflow, root water uptake and soil water flow into account? Finally, I will include soil water isotope depth profiles to constrain tracer-aided models and relate travel times in the soil to catchment travel times. The latter is a follow up to my PhD thesis and currently ongoing postdoctoral work.

• DFG Programme: Research Fellowships
• International Connection: Spain, USA
• Hosts: Professor Dr. Ryan E. Emanuel, since 8/2018; Dr. Jérôme Latron, from 7/2018 until 8/2018