Toute l'actualitéOn 17 September 2026, the World Meteorological Organization (WMO) published the fifth edition of its State of Global Water Resources report, assessing the state of global water resources in 2025. Based on fifteen hydrological variables – including river discharge, groundwater, soil moisture, lakes, snow, glaciers and terrestrial water storage – this latest edition also provides a retrospective analysis of the past five years. It highlights recurring hydrological anomalies across many regions of the world, simultaneously affecting water flows, available reserves and their distribution over time and space. For businesses, the challenge is therefore no longer simply to assess the current availability of water resources, but to understand to what extent economic activities can remain resilient when hydrological conditions repeatedly diverge from historical reference conditions.
Repeated departures from historical reference conditions
To assess the state of water resources, the WMO compares values observed in 2025 with historical reference periods. One of the report’s most significant findings concerns river discharge. In 2025, around 36% of the world’s watershed area experienced river discharge below the reference range, while 36% remained within it. Globally, 2025 therefore ranked among the driest years in terms of river discharge over the past 35 years.
Taken in isolation, such a result could simply reflect year-to-year variability. However, the WMO’s retrospective analysis reveals that these anomalies have been recurring: over the past seven years, the share of global watershed area with river discharge within the historical reference range has remained between 34% and 38%, compared with an average of 46% over the 1991–2020 period. Recurring deficits have notably been observed across North America, the Amazon and La Plata watersheds, Central and East Africa, Central Asia and the Middle East.
For businesses, repeated departures from historical reference conditions now make it essential to better integrate hydrological variability into investment, location, sourcing and risk management decisions.
Water availability depends on more than precipitation
The amount of rainfall received by an area does not, in itself, determine the actual availability of water. This also depends on the capacity of water to be stored in soils, groundwater, lakes, snow and glaciers, and then released over time.
The report examines Terrestrial Water Storage (TWS), which encompasses these different reserves. Unlike river discharge, which responds relatively quickly to changes in precipitation and snowmelt, this indicator captures slower developments such as groundwater depletion, declining reserves and ice loss.
Since 2014–2016, the WMO has observed a persistent decline in terrestrial water storage, with a growing proportion of land areas recording levels below their historical reference conditions. Overall, the report finds that the world’s land areas are now holding less freshwater than they did previously.
Groundwater provides further evidence of these pressures. In 2025, among monitoring stations with usable data, 65% recorded average annual groundwater levels outside the reference range, while 34% reported below- or much-below-normal levels. Persistent deficits were observed in particular across Central and Eastern Europe, the United States, Mexico, Chile, Brazil, South Africa, India and Australia.
Changes in the cryosphere add another dimension. Between 2023 and 2025, glaciers worldwide lost around 1,400 billion tonnes of water. 2025 was the fourth consecutive year in which every major glaciated region recorded a net loss of mass. Some regions may even have already passed peak water – the point at which the contribution of glacier meltwater reaches its maximum before beginning to decline.
From water stress to hydrological variability
The report also highlights a broader reality: water risk is not limited to water scarcity. The past five years have certainly been marked by major multi-year droughts in the Amazon and La Plata watersheds, the Middle East and the Horn of Africa. At the same time, severe flooding has repeatedly affected West and Central Africa as well as South-East Asia.
These contrasts were particularly evident in 2025. While Eastern Europe, the Mediterranean and the Middle East experienced severe drought, several regions of Africa and Asia faced extreme rainfall and major flooding.
Between 2021 and 2025, around 1,500 water-related extreme events were recorded in the EM-DAT database, causing at least 62,500 deaths. Asia and Africa alone accounted for almost half of all recorded events and more than 80% of associated deaths.
Water risk therefore also encompasses excess water, rainfall seasonality, variations in river flow, the state of water reserves and the alternation between dry and wet periods. For businesses, these different dimensions can affect operational continuity, the availability of certain raw materials, infrastructure performance and the resilience of the areas on which their value chains depend.
The watershed: a key scale for understanding risk
Water is inherently local. An economic activity does not depend on water availability at a global or even national level, but on the functioning of a particular watershed: rainfall patterns, the condition of soils and groundwater, seasonal river flows, competing uses and the ability of the landscape to retain and release water. Two sites withdrawing similar volumes of water may therefore face very different levels of risk depending on their hydrological context.
This calls for an approach to water management that goes beyond volumes alone. Measuring withdrawals, reducing consumption and improving process efficiency remain essential, but are not sufficient to characterise the water vulnerability of an activity. Businesses also need to understand where water is withdrawn, when it is withdrawn, the condition of the area’s different water reserves and how the local hydrological cycle is evolving. The watershed therefore provides a particularly relevant scale for connecting economic dependencies with ecological realities.
Strengthening territorial resilience in the face of increasing water variability
The WMO report is deliberately scientific and retrospective: its primary purpose is to provide a knowledge base that can inform strategies, public policy and investment decisions. Its findings nevertheless point to the need to rethink how water risk is understood.
When departures from historical reference conditions become recurrent, the challenge can no longer consist solely in securing a given volume of water at a particular point in time. It also becomes necessary to strengthen the capacity of territories to absorb both periods of deficit and excess, while preserving the functions that enable water to infiltrate, be stored and circulate over time.
From this perspective, Nature-based Solutions can complement water-efficiency measures and water-management infrastructure by supporting the ecological functioning of watersheds. Soil and ecosystem restoration, vegetation cover and agroforestry practices can therefore be designed not as generic responses, but according to the specific vulnerabilities of each area and the hydrological functions that need to be strengthened. This approach requires a shift from a model focused solely on the immediate availability of water resources towards one centred on territorial water resilience.
The WMO concludes its retrospective analysis with three questions: how are water resources changing globally? Do the observed changes reflect variability, emerging trends or more structural shifts? And do we have sufficient data to determine the answer? For businesses, a further question arises: are their strategies prepared for a context in which departures from historical hydrological reference conditions recur – sometimes in opposite forms – across the areas on which they depend?