Sebastian Gnann

Project: Groundwater processes in conceptual hydrological models

Supervisors: Dr Nicholas Howden and Dr Ross Woods

Understanding and modelling baseflow and groundwater processes is crucial for various issues related to water quantity and quality and of global importance as baseflow and groundwater are major water resources. This project aims at identifying and quantifying the major controls on catchment scale groundwater processes, such as climate forcing (e.g. precipitation, potential evapotranspiration) and catchment form (geology, vegetation, soils, topography, etc.). We try to describe and model how these controls interact (i.e. how catchments work as natural systems) in a process-based way. This implies identifying the key processes and describing them in an adequate way (ideally simple, but not too simple). Process-based models are required for extrapolation, i.e. predicting beyond the range of what we have observed. This is necessary in the face of environmental change (land use change, climate change) and for predictions in ungauged catchments. Ideally, parameters used in these models should be linkable to physical (observable) attributes, which would allow to define them a-priori (if the relevant information is available) and thus make them transferable to ungauged catchments. One way to approach these challenges is to analyse large samples of catchments to find (dis-)similarities and patterns that might be synthesised to catchment-scale theory (comparative hydrology). This approach is employed in one research project, which focuses on the influence of long-term climate and landscape characteristics on annual baseflow generation. Using many catchments located in the US and the UK, we explore how variations in annual baseflow can be attributed to aridity and catchment form. Besides a better understanding of the environment and more robust predictions, improved process understanding might help to constrain and improve hydrological models (i.e. getting the right answers for the right reasons).

Sebastian graduated from the University of Tuebingen, Germany, with a B.Sc. in Environmental Science and a M.Sc. in Applied & Environmental Geoscience. During his Master’s, he specialised in Hydrogeology and Environmental Physics & Modelling. For his Master’s thesis, he focused on multivariate geostatistics and stochastic modelling of environmental variables.

Research Interests

  • Catchment hydrology
  • Hydrogeology
  • Environmental and hydrological modelling
  • Geostatistics


WISE 2017 Summer School Presentation: Sebastian_Gnann_Jun17[1]

June 2017 Poster: Sebastian Gnann Jun17