Twenty-three unsolved problems in hydrology (UPH)–a community perspective

Blöschl, G. and Bierkens, M.F.P. and Chambel, A. and Cudennec, C. and Destouni, G. and Fiori, A. and Kirchner, J.W. and McDonnell, J.J. and Savenije, H.H.G. and Sivapalan, M. and Stumpp, C. and Toth, E. and Volpi, E. and Carr, G. and Lupton, C. and Salinas, J. and Széles, B. and Viglione, A. and Aksoy, H. and Allen, S.T. and Amin, A. and Andréassian, V. and Arheimer, B. and Aryal, S.K. and Baker, V. and Bardsley, E. and Barendrecht, M.H. and Bartosova, A. and Batelaan, O. and Berghuijs, W.R. and Beven, K. and Blume, T. and Bogaard, T. and Borges de Amorim, P. and Böttcher, M.E. and Boulet, G. and Breinl, K. and Brilly, M. and Brocca, L. and Buytaert, W. and Castellarin, A. and Castelletti, A. and Chen, X. and Chen, Y. and Chifflard, P. and Claps, P. and Clark, M.P. and Collins, A.L. and Croke, B. and Dathe, A. and David, P.C. and de Barros, F.P.J. and de Rooij, G. and Di Baldassarre, G. and Driscoll, J.M. and Duethmann, D. and Dwivedi, R. and Eris, E. and Farmer, W.H. and Feiccabrino, J. and Ferguson, G. and Ferrari, E. and Ferraris, S. and Fersch, B. and Finger, D. and Foglia, L. and Fowler, K. and Gartsman, B. and Gascoin, S. and Gaume, E. and Gelfan, A. and Geris, J. and Gharari, S. and Gleeson, T. and Glendell, M. and Gonzalez Bevacqua, A. and González-Dugo, M.P. and Grimaldi, S. and Gupta, A.B. and Guse, B. and Han, D. and Hannah, D. and Harpold, A. and Haun, S. and Heal, K. and Helfricht, K. and Herrnegger, M. and Hipsey, M. and Hlaváčiková, H. and Hohmann, C. and Holko, L. and Hopkinson, C. and Hrachowitz, M. and Illangasekare, T.H. and Inam, A. and Innocente, C. and Istanbulluoglu, E. and Jarihani, B. and Kalantari, Z. and Kalvans, A. and Khanal, S. and Khatami, S. and Kiesel, J. and Kirkby, M. and Knoben, W. and Kochanek, K. and Kohnová, S. and Kolechkina, A. and Krause, S. and Kreamer, D. and Kreibich, H. and Kunstmann, H. and Lange, H. and Liberato, M.L.R. and Lindquist, E. and Link, T. and Liu, J. and Loucks, D.P. and Luce, C. and Mahé, G. and Makarieva, O. and Malard, J. and Mashtayeva, S. and Maskey, S. and Mas-Pla, J. and Mavrova-Guirguinova, M. and Mazzoleni, M. and Mernild, S. and Misstear, B.D. and Montanari, A. and Müller-Thomy, H. and Nabizadeh, A. and Nardi, F. and Neale, C. and Nesterova, N. and Nurtaev, B. and Odongo, V.O. and Panda, S. and Pande, S. and Pang, Z. and Papacharalampous, G. and Perrin, C. and Pfister, L. and Pimentel, R. and Polo, M.J. and Post, D. and Prieto Sierra, C. and Ramos, M.-H. and Renner, M. and Reynolds, J.E. and Ridolfi, E. and Rigon, R. and Riva, M. and Robertson, D.E. and Rosso, R. and Roy, T. and Sá, J.H.M. and Salvadori, G. and Sandells, M. and Schaefli, B. and Schumann, A. and Scolobig, A. and Seibert, J. and Servat, E. and Shafiei, M. and Sharma, A. and Sidibe, M. and Sidle, R.C. and Skaugen, T. and Smith, H. and Spiessl, S.M. and Stein, L. and Steinsland, I. and Strasser, U. and Su, B. and Szolgay, J. and Tarboton, D. and Tauro, F. and Thirel, G. and Tian, F. and Tong, R. and Tussupova, K. and Tyralis, H. and Uijlenhoet, R. and van Beek, R. and van der Ent, R.J. and van der Ploeg, M. and Van Loon, A.F. and van Meerveld, I. and van Nooijen, R. and van Oel, P.R. and Vidal, J.-P. and von Freyberg, J. and Vorogushyn, S. and Wachniew, P. and Wade, A.J. and Ward, P. and Westerberg, I.K. and White, C. and Wood, E.F. and Woods, R. and Xu, Z. and Yilmaz, K.K. and Zhang, Y. (2019) Twenty-three unsolved problems in hydrology (UPH)–a community perspective. Hydrological Sciences Journal, 64 (10). pp. 1141-1158. ISSN 0262-6667

Abstract

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.