Stefanie Lutz, Helmholtz Centre for Environmental Research UFZ Leipzig, Hydrogeology, Leipzig, Germany, Tim H M van Emmerik, Wageningen University and Research Center, Hydrology and Quantitative Water Management Group, Wageningen, Netherlands, Andrea L. Popp, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Duebendorf, Switzerland, Sina Khatami, University of Melbourne, Parkville, VIC, Australia and Wouter Knoben, University of Saskatchewan, Canmore, Canada