The World Meteorological Organization (WMO) has published the first report on the state of the world’s water resources , assessing the effects of climate, environmental and social change on the Earth’s water resources. . The objective of this annual balance sheet is to support the monitoring and management of the world’s freshwater resources at a time characterized by increasing demand and limited supply.
The report provides a summary of the river flow, as well as the main floods and droughts. Perspectives are offered on hotspots in terms of changes in freshwater storage, while highlighting the essential role and vulnerability of the cryosphere (snow and ice).
The report notes that drier-than-normal conditions were recorded across large areas of the planet in 2021, a year in which rainfall distribution was influenced by climate change and a La Niña episode. The area with below-mean stream flow was approximately twice as large as the area above the mean, compared to the 30-year hydrologic mean.
“The impacts of climate change tend to manifest themselves through water, with more intense and frequent droughts, more extreme floods, more irregular seasonal rains and the acceleration of the melting of glaciers, and generate cascading effects on economies, ecosystems and all aspects of our daily lives. However, insufficient knowledge is available on changes in the distribution, quantity and quality of freshwater resources,” said WMO Secretary-General Professor Petteri Taalas.
“The State of the World’s Water Resources report aims to fill this knowledge gap and provide a concise overview of water availability in different parts of the world. These data will guide investments in climate-linked mitigation and adaptation activities, as well as the United Nations campaign to focus on providing universal access within the next five years to early warnings of hazards such as floods and droughts.” added Professor Taalas.
Currently, 3.6 billion people have inadequate access to water for at least one month of the year, and this number is projected to increase to more than 5 billion by 2050. Between 2001 and 2018, UN-Water gave to know that 74% of all natural disasters were related to water. At the recent United Nations climate change conference (27th Conference of the Parties to the United Nations Framework Convention on Climate Change), governments were urged to further integrate water into adaptation initiatives, which It marks the first time that water has been referred to in an outcome document of a Conference of the Parties in recognition of its critical importance.
In the first edition of the report, river flow is examined, that is, the volume of water that flows through a river channel at a given time. Likewise, terrestrial water storage is evaluated, that is, all the water found on the terrestrial surface and subsurface and the cryosphere (frozen water).
The information and supplementary maps are based primarily on modeled data (for maximum geographic coverage) as well as remotely sensed information from the Gravity Recovery Experiment and Climate (GRACE) land-based water storage mission. National Aeronautics and Space Administration (NASA). Model results were validated against observed data, where available.
In the report, the lack of verified and accessible hydrological data is emphasized. The WMO Unified Data Policy seeks to accelerate the availability and sharing of hydrological data, including information on river flows and transboundary river basins.
River flow
Drier-than-normal conditions were recorded in 2021 over large areas of the globe, compared to the average 30-year reference hydrological period.
Among them, it is worth mentioning the Río de la Plata area in South America, where a persistent drought has affected the region since 2019, the south and southeast of the Amazon, and some basins in North America, for example, the of the Colorado, Missouri, and Mississippi rivers.
In Africa, some rivers, including the Niger, Volta, Nile, and Congo, had lower-than-normal flows in 2021. Also, some rivers in parts of Russia, western Siberia, and Central Asia had below-average flows. in 2021.
Higher-than-normal river flows were observed in some basins in North America, northern Amazonia, and southern Africa (Zambezi and Orange), as well as in China (the Amur River basin) and northern India.
Approximately one third of the areas analyzed corresponded to the 30-year average.
Major floods with many casualties have been reported, for example, in China (Henan Province), northern India, western Europe and tropical cyclone-affected countries such as Mozambique, the Philippines and Indonesia.
Ethiopia, Kenya and Somalia have faced several consecutive years of below-average rainfall that have caused a regional drought.
Source: World Meteorological Organization