HESS Opinions: Towards a common vision for the future of hydrological observatories. - Nasta, Paolo; Blöschl, Günter; Bogena, Heye R.; Zacharias, Steffen; Baatz, Roland; De Lannoy, Gabriëlle; Jensen, Karsten H.; Manfreda, Salvatore; Pfister, Laurent; Tarquis, Ana M.; van Meerveld, Ilja; Voltz, Marc; et al. (Hydrology & Earth System Sciences, 2025)