How old is streamwater? Open questions in catchment transit time conceptualization, modelling and analysis

McDonnell, J. J.; McGuire, K.; Aggarwal, P.; Beven, K. J.; Biondi, D.; Destouni, G.; Dunn, S.; James, A.; Kirchner, J.; Kraft, P.; Lyon, S.; Maloszewski, P.; Newman, B.; Pfister, L.; Rinaldo, A.; Rodhe, A.; Sayama, T.; Seibert, J.; Solomon, K.; Soulsby, C.; Stewart, M.; Tetzlaff, D.; Tobin, C.; Toch, P.; Weiler, M.; Western, A.; Worman, A.; Wrede, S. 2010. How old is streamwater? Open questions in catchment transit time conceptualization, modelling and analysis. Hydrological Processes. 24: 1745-1754.