Minimize disruptions to the timing and quantity of the water cycle

The quantity and timing of freshwater moving through the global hydrologic cycle is impacted significantly by the growing footprint of urbanized landscapes, characterized by surface coverage of impermeable and artificial materials like concrete.

These surfaces accelerate the rate of surface water runoff during rainfall events, resulting in higher flood risk and reducing replenishment of groundwater. And, just as urbanization impacts these flow patterns, changes to local and regional hydrological regimes — driven in large part by climate change — also impact cities. For example, increased rainfall over a city requires that city’s infrastructure to adapt to greater quantities of water over shorter periods of time.

To address the growing complexities associated with urban stormwater runoff in a changing climate, effective management is paramount. Measures to equip governments to more effectively manage these flows include, but are not limited to, use of permeable materials for infrastructure development, installation of green stormwater infrastructure such as bioswales and rain gardens, and deployment of stormwater capture and retention systems designed to slow and store runoff.

However, at the time of publishing, an up-to-date global dataset indicating the extent of adopted stormwater runoff management measures was not available.

In many parts of the world, legislation that protects environmental flows has proven to be an effective strategy for maintaining sufficient such flows. Although it takes different forms, such legislation generally focuses on protecting or mandating the provision of a certain level of environmental flows, often in historically unregulated river ecosystems that are at risk of, or already suffering from, overabstraction.

There is no globally comprehensive dataset that measures the number of countries that have instated legal protections to maintain or increase environmental flows, but case studies from around the world suggest uptake of this policy approach by a diverse array of governments.

For instance, in response to the European Union’s formative 2000 Water Framework Directive, which acknowledges the importance of environmental flow regimes, France, Spain and Romania have embedded environmental flow requirements into national law.

Governments in other countries including Australia, Canada, China, India, Mexico, South Africa, the United States and Zambia have also all legislated some form of environmental flow regulations. Cases vary from South Africa’s wide-reaching National Water Act, which requires specifically earmarked reserves of water for sustaining ecological function across the country, to regulatory approaches in the United States, where environmental flow requirements are often enforced through minimum flow standards at the state level.

Ultimately, in light of the proven benefits of these arrangements, increased uptake of these legislative tools, as well as further research and trial of similar policy mechanisms like water footprint caps, will be instrumental to ensure sufficient levels of environmental flows for people and nature.

Demand for the goods and services that freshwater provides is growing swiftly: By one estimate, water withdrawals around the world have increased almost twice as fast as global population growth. But, given the limitations of the world’s sustainable freshwater supply, enhancing the efficiency of how we use water for agriculture, industry and other services is vital.

Improving water use efficiency reduces the amount of surface and groundwater that is withdrawn for human activities, leaving flows available for aquatic ecosystems, reducing habitat disruption, improving water quality in downstream ecosystems and preventing further degradation, such as waterlogging and salinization, that affects environmental health and people’s well-being. Enhancing efficiency also offers multiple co-benefits, such as reducing emissions from water pumping and distribution, improving soil health and boosting resilience to drought and other climate impacts. It also leads to higher crop yields, better food security and increased economic productivity within the agricultural industry.

It is thus promising that, over the last two decades, the world has seen an increase in water use efficiency, measured by the monetary value added per volume of water withdrawn. The most recent available data shows that global water use efficiency increased from $13 per cubic meter in 2000 to $21 per cubic meter in 2021. Yet, as there are wide differences in water use efficiency across the world (see map view), interventions to enhance efficiency in particularly water-stressed regions, including the Middle East, North Africa and South Asia, should be prioritized.

There is no-one-size-fits-all approach to achieving such gains around the world, but there is evidence that agricultural interventions — including investments in water-efficient irrigation systems and application of mulching and cover crops — water reuse and reclamation in industrial processes, and water pricing mechanisms that incentivize efficient household consumption — can yield tangible improvements.

Some water management experts believe that water resources should be strategically priced in order to incentivize more efficient water usage. Water pricing or tariff schemes involve setting water prices that better internalize the costs that governments and utilities incur to supply sufficient water quantity and quality to agricultural, industrial and domestic users.

There is much evidence that when this price is set close to or at the marginal cost of delivering a unit of water, water use efficiency improves: In other words, because users are incentivized to only pay for the water that they truly need, they typically reduce inefficient, nonessential water uses that they do not value highly.

Historically, water prices, particularly in developed countries, have been understood to be too low to encourage reductions in nonessential consumption. Nonetheless, it is encouraging that the average price of water tariff programs implemented around the world is increasing over time: for instance, the average water price for water deliveries of up to 6 cubic meters per month increased from nearly $4 per cubic meter in 2022 to $8 per cubic meter in 2025, while the price for water deliveries of up to 15 cubic meters per month grew from $10 per cubic meter to $22 per cubic meter over that same period. In one notable success story, a water tariff enacted to reflect the growing value and scarcity of water in Singapore has led to sustained efficiency improvements, with the government continuing to steadily increase the tariff price over time.

There are many ways in which water managers and governments can ensure that prices on water do not disproportionately impact communities living in poverty. Increasing block tariffs — pricing structures in which water users pay much lower rates for a certain quantity of water deemed necessary to meet basic services, and thereafter pay higher rates on additional withdrawals — can help to ensure that poorer users are not priced out of water services. Other proposals aim to make water pricing more equitable, such as rebates to cover water costs for low-income households and “lifeline” water allocations provided at little or no cost to ensure access to basic water services. Despite the importance of monitoring the extent to which water pricing mechanisms around the world meet key equity criteria, however, there is no available data to do so at this time.

Managing water resources and minimizing disruptions to water quantity and timing, particularly in the midst of a changing climate, requires an understanding of the amount and spatial distribution of water flows and stocks and how these variables are changing over time. It is thus paramount that meteorological, water resource and environmental agencies prioritize the development and continuous updating of ground- and satellite-based monitoring systems that can measure surface and groundwater resources in real time and inform resultant water policy decision-making.

As of 2025, 70% of countries publicly reported surface water data, groundwater data or both, demonstrating widespread global efforts to track these critical freshwater stocks. Tracking whether this share is growing over time will be essential to determine whether countries are increasingly prioritizing monitoring efforts.

When constructed and operated with stringent safeguards in place to prevent damaging ecosystem degradation, existing hydropower dams can play a vital role in delivering clean, firm renewable power while also providing benefits for storage, diversion and regulation of water for agricultural, industrial and domestic uses.

However, dams can also threaten freshwater flows and stocks, resulting in unintended and adverse consequences for water quantity and timing. For instance, while structural flood control measures such as levees and channelization may reduce flooding locally in the short term, in some cases they can increase downstream flood risks or lead to more severe impacts when infrastructure fails. Furthermore, the disconnection of rivers from their floodplains, often caused by dams and levees that regulate water flows — particularly high-flow events — can actually increase downstream flood risk while reducing the goods and services provided by fertile, functional floodplains and resilience to climate change.

The growing impacts of climate change are only exacerbating the threats that existing dams can pose to freshwater quantity and timing. One study demonstrated that more frequent heavy rains in the United States are increasing the likelihood of dam failure events, subjecting greater numbers of people and ecosystems to flooding. Yet, as traditional dam safety management assumes stationary climate conditions, many existing dams are not equipped to manage these growing climate risks.

It will thus be increasingly important to equip existing dams with updated operating rules or climate risk screening processes that account for a nonstationary and changing climate. Such measures may include adjusting existing flood estimation procedures and tailoring reservoir release schedules to incorporate changes to flow regimes; however, to date there is no comprehensive global dataset measuring the number and location of dams where such rules have already been implemented.