Open Science in hydrology – 100 years of precursors and actual tectonics from the IAHS perspective

IAHS has developed over the last 100 years with a key role for the discipline, the community and society. IAHS and committed individuals have defended values, implemented mechanisms, facilitated partnerships and catalysed outcomes which were precursors of the now-called Open Science paradigme. Actual developments within IAHS (including agenda-setting, synthesis, editorial and curating initiatives), across cooperations with sister associations and other learned societies (water-related, interfacing geosciences within IUGG, generic or systemic aspects within ISC), and across tangible partnerships with UN agencies and programmes (UNESCO IHP, WMO, and the wider UN Water dynamics) are strong contributions to the ongoing tectonic of Open Science in the field of hydrology. A panoramic view of these historical roots and actual developments shall allow to identify strengths, weaknesses and paths for IAHS and the hydrological community to contribute to the paradigme shift that is required, as called by the multilateral UNESCO recommendation on Open Science (2021), and knowing the increasing societal need for reinforced hydrological knowledge and methods in the frame of Agenda 2030 and beyond.