WMO State of Global Water Resources 2021
Geneva, 29 November 2022
The World Meteorological Organization has published its first State of Global Water Resources report. It provides insights into the availability of freshwater in different parts of the world and highlights major flood and drought events. In its first edition, the assessment is limited to streamflow, terrestrial water storage and the cryosphere. However, it is intended to include groundwater, soil moisture and water quality in the future. The preparation of the 2021 report was largely based on simulated data from hydrological models and remote sensing information from satellite missions. These were compared and validated against observational data. Despite good correlation, the validation between modelled and observed results would benefit substantially from more hydrological information, as WMO Secretary-General Prof. Petteri Taalas pointed out. He called on Member States to share more hydrological information in line with the WMO Unified Data Policy. Thereby he acknowledged the importance and contribution of the Global Data Centres. The report provides world leaders, decision-makers and citizens with information on the state of water resources for the first time and is an important step towards accurate water data and early warning systems in preparation for the United Nations 2023 Water Conference, COP28 and the 2030 Agenda for Sustainable Development.
The classification of hydrological basins for the global streamflow analysis of the assessment was based on the WMO Basins and Sub-Basins dataset of GRDC. In addition, observational river discharge data from GRDC were used for the validation of simulated river discharge data from Global Hydrological Modelling Systems. Data of the International Soil Moisture Network (ISMN) have also been utilised for the assessment report. The head of GRDC, Ulrich Looser, was also involved in the preparation and review of the assessment report. Petteri Taalas states that WMO is committed to extending the variables in future editions of the report to include groundwater, soil moisture and water quality. Here, UNEP’s GEMS/Water Data Centre, operated by ICWRGC and BfG, will also contribute in the future. Most of the global water data centres are part of the Global Terrestrial Network – Hydrology (GTN-H), a joined initiative of WMO and the Global Climate Observing System, coordinated by ICWRGC. In this context it is gratifying that the gaps in water and climate observation systems are also emphasized in the COP27 Cover Decision. Closing Gaps in water data and observations are also discussed as Game Changers for the Water Action Agenda and will support the discussions in the proposed five interactive dialogues of the 2023 UN Water Conference.