1 Illinois Water Resources Center and Illinois State Geological Survey, Prairie Research Institute, University of Illinois Urbana-Champaign, Champaign, Illinois, USA.
2 British Geological Survey, UK Research and Innovation, Wallingford, UK.
3 Applied and Environmental Geology, Hydrogeology Research Group, Department of Environmental Sciences, University of Basel, Basel, Switzerland.
4 Geological Survey of Spain, Spanish National Research Council, Madrid, Spain.