In many regions of the world, groundwater is the most important drinking water resource and is also of great importance in agriculture and industry. Ecosystems such as wetlands, rivers and lakes are also dependent on groundwater. As a hydrogeologist, I develop methods for simulating and analysing groundwater systems. I am particularly interested in changes in water quantity and water quality at springs and in groundwater monitoring wells.

Groundwater in climate change

In my research, I am interested in the effects of climate change on the quantity and quality of groundwater and how these differ from direct human interventions and natural influences. In order to better understand the influence of indirect effects of climate change, such as climate-induced changes in vegetation or land use, I combine hydrogeological methods of groundwater research with approaches from other disciplines and work together with partners from different research areas.

For example, projects in the Earth System Sciences (ESS) programme of the Austrian Academy of Sciences (ÖAW) were carried out together with colleagues from agricultural sciences and ecology as well as with practitioners from the fields of water management and agriculture: The Integrative Groundwater Assessment project investigated how groundwater systems in an alpine and pre-alpine environment respond to extreme hydrological events such as droughts or floods in terms of water quantity and chemical quality as well as ecological status (final report available here); the ClimGrassHydro project aimed to understand how the ecohydrology of grassland and thus groundwater recharge is affected by the individual and combined effects of global warming, severe drought and elevated CO₂ concentration in the atmosphere (final report available here).

Karst groundwater

Karst aquifers are formed in soluble rocks such as limestone or gypsum. Water flowing through fractures in such rocks widens the existing pathways due to the dissolution of rock, thus creating highly conductive karst conduits. However, the karst conduit system only represents a small part of the total porosity of the aquifer. Most of the storage volume is provided by fractures that are not significantly widened and/or the porous rock matrix. Karst aquifers are important water resources that supply a significant proportion of the world's population with drinking water. Due to the high flow velocities in highly the karst conduits, pollutants introduced into karst aquifers can spread rapidly. Effective protection and sustainable use of these vulnerable water resources therefore requires in-depth knowledge of the structure and functioning of these aquifers. In my research on this topic, I use process-based modelling approaches to interpret field observations at springs or tracing tests.

Selected publications on process-based characterisation and modelling of karst aquifers:

Kavousi, A., Reimann, T., Wöhling, T., Birk, S., Luhmann, A.J., Kordilla, J., Noffz, T., Sauter, M., Liedl, R. (2023): Joint inversion of groundwater flow, heat, and solute state variables: a multipurpose approach for characterisation and forecast of karst systems. Hydrogeology Journal 31 (4): 1005-1030. doi: 10.1007/s10040-023-02631-8

Abirifard, M., Birk, S., Raeisi, E., Sauter, M. (2022): Dynamic volume in karst aquifers: Parameters affecting the accuracy of estimates from recession analysis. Journal of Hydrology, 612, 128286. doi: 10.1016/j.jhydrol.2022.128286

Mayaud, C., Wagner, T., Benischke, R., Birk, S. (2014): Single event time series analysis in a binary karst catchment evaluated using a groundwater model (Lurbach system, Austria). Journal of Hydrology 511: 628-639. doi: 10.1016/j.jhydrol.2014.02.024

Birk, S., Hergarten, S. (2010): Early recession behaviour of spring hydrographs. Journal of Hydrology 387: 24-32. doi:10.1016/j.jhydrol.2010.03.026

Geyer, T., Birk, S., Liedl, R., Sauter, M. (2008): Quantification of temporal distribution of recharge in karst systems from spring hydrographs. Journal of Hydrology 348 (3): 452-463. doi:10.1016/j.jhydrol.2007.10.015

Hergarten, S., Birk, S. (2007): A fractal approach to the recession of spring hydrographs. Geophysical Research Letters 34, L11401, doi:10.1029/2007GL030097.

Geyer, T., Birk, S., Licha, T., Liedl, R., Sauter, M. (2007): Multi-tracer test approach to characterise reactive transport in karst aquifers. Ground Water 45 (1): 36-45. doi: 10.1111/j.1745-6584.2006.00255.x.

Birk, S., Liedl, R., Sauter, M. (2006): Karst spring responses examined by process-based modelling. Ground Water 44 (6): 832-836. doi: 10.1111/j.1745-6584.2006.00175.x.

Birk, S., Geyer, T., Liedl, R., Sauter, M. (2005): Process-based interpretation of tracer tests in carbonate aquifers. Ground Water 43 (3): 381-388.