HESS Opinions: Towards a common vision for the future of hydrological observatories - Nasta, P; Blöschl, G; Bogena, HR; Zacharias, S; Baatz, R; De Lannoy, G; Jensen, KH; Manfreda, S; Pfister, L; Tarquis, AM; van Meerveld, I; Voltz, M; et al. (Hydrology And Earth System Sciences, 2025)