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The year 2023 was the driest for global rivers in the past 33 years, The State of Global Water Resources report by the World Meteorological Organization (WMO), released on October 7, 2024, revealed. The report highlighted severe stress on global water supplies.
In fact, the past five consecutive years have recorded widespread below-average river flows and reservoir inflows, reducing the amount of water available for communities, agriculture and ecosystems.
With 2023 being the hottest year on record, increasing temperatures and widespread dry conditions contributed to prolonged droughts. Compared to the historical period (1991–2020), rivers mostly faced conditions that were drier-than-average to average for river discharge, the report said.
Similar to 2022 and 2021, more than half of global catchment areas in 2023 showed deviations from near-average conditions for river discharge, predominantly lower than average, with fewer basins exhibiting above- or much-above-average conditions.
In an era of growing water demand, the report showed a rising trend in dry areas over time, with 2023 being the driest year in the last three decades, followed by 2021 and 2015. Below- and much-below-average conditions affected North America (except Alaska), Central America and South America.
Meanwhile, in Asia, large river basins such as those of the Ganga and Brahmaputra experienced lower-than-average conditions across almost their entire territories. Discharge conditions also remained lower than average across the West and Central Asia.
The transition from La Niña (2022-2023) to El Niño (2023) appears to have been a key climatic driver in this record-breaking dry and warm situation, combined with a widespread anomalous warming over the worldwide ocean.
The report, now in its third year, indicated that inflow into reservoirs in 2023 generally reflected the overall discharge conditions, with the global balance being mostly below average or average.
Specifically, reservoirs in India, especially along the west coast, experienced below- and much-below-average inflows. However, the Ganga river basin in India saw above-average reservoir storage.
Reservoir storage is influenced not only by climatic conditions and inflows but also by human regulation of the storage. Even when inflows are low, water can be stored, increasing reservoir volumes but decreasing discharge downstream.
Meanwhile, in Australia, the Murray-Darling river also recorded below-average inflows. In North and South America, reduced water availability was evident, with lower-than-usual inflows into reservoirs, particularly in the Mackenzie river in North America, across Mexico and in the Paraná river in southern Brazil and Argentina.
Across the West and Central Asia, inflows into reservoirs remained lower than usual.
In 2023, average groundwater levels were much below average in 19 per cent of monitored wells, below average in 11 per cent, average in 40 per cent, above average in 10 per cent and much above average in 20 per cent.
A large part of North America, central and northern Chile, western and southern Brazil, southern Europe (Portugal, Spain, most of France), central Europe (Hungary, Austria, Bavaria, northern Poland), as well as western and southern Australia, were regions where average groundwater levels were below or much below average in a high proportion of wells.
Conversely, groundwater levels were above or much above average in a high proportion of wells in New England (United States), the Maritime provinces of Canada, along the Atlantic coast of north-eastern Brazil, northern Europe (the British Isles and Scandinavia), Israel, southern Africa, parts of India, the Republic of Korea, eastern Australia and the North Island of New Zealand.
High precipitation also directly contributes to rising groundwater levels by recharging aquifers and this effect was observed in some parts of India.
The year 2023 ranked just behind 2022 in recent historical records for dry soils. Soil moisture in 2023 was predominantly below or much below average across large areas globally throughout the year.
For example, almost all of North America, South America, North Africa and West Asia experienced much-below-average soil moisture levels, particularly during June, July and August.
During the same period (June-August), almost all of Europe, the Russian Federation, Central Asia and China experienced below- to much-below-average soil moisture conditions.
However, Alaska, north-eastern Canada, India and the north-eastern Russian Federation experienced much-above-average soil moisture conditions.
Currently, 3.6 billion people face inadequate access to water for at least one month every year and this number is expected to rise to more than five billion by 2050, according to United Nations Water.
“…far too little is known about the true state of the world’s freshwater resources. We cannot manage what we do not measure. This report seeks to contribute to improved monitoring, data-sharing, cross-border collaboration and assessments,” said WMO Secretary-General Celeste Saulo.