State of Global Water Resources 2021
The State of Global Water Resources 2021 report, published by the World Meteorological Organization (WMO) in November 2022, outlines water availability in different parts of the world and assesses the effects of climate, environmental and societal change on the Earth’s water resources.
The aim of this annual stocktake is to support the monitoring and management of global freshwater resources in an era of growing demand and limited supply. The report summarises river flow, major floods and droughts. It provides insights into hotspots for changes in freshwater storage and highlights the crucial role and vulnerability of the cryosphere (snow and ice).
The first edition of the report looks at streamflow – the volume of water flowing through a river channel at any given time. It also assesses terrestrial water storage, i.e. all water on the land surface and sub-surface, as well as in the cryosphere.
According to the report, large areas of the globe recorded drier than normal conditions in 2021 – a year in which precipitation patterns were influenced by climate change and a La Niña event. The area with below-average streamflow was approximately two times larger than the above-average area, in comparison with the 30-year hydrological average.
The information and accompanying maps are largely based on modelled data (to achieve maximum geographical coverage) and, for terrestrial water storage, on remotely sensed information from NASA’s Gravity Recovery and Climate Experiment (GRACE). The modelled results were validated against observed data, wherever available.
The report highlights the lack of accessible verified hydrological data. WMO’s Unified Data Policy seeks to accelerate the availability and sharing of hydrological data, including river discharge and transboundary river basins information.
Read more on the WMO website