Research in support of the UN 2023 Water Conference

A promise is a promise. The world must do much better in the second half of the 2030 Agenda timeline to deliver on the 17 SDGs, not least to address the inequalities impacting women and girls by inadequate water, sanitation and hygiene.

Improving sanitation technology and service is imperative for everyone, in every country.

China’s history of large-scale water, sanitation and clean energy investments offers promising insights into the development of new interventions to reduce linear growth faltering among children and adolescents.

The alarmingly slow progress on water-related goals and targets jeopardizes the entire sustainable development agenda. In March 2023, the United Nations (UN) convened the first UN Water Conference in nearly 50 years to create momentum and accelerate progress. The outcome of the conference will feed into the High-level Political Forum on Sustainable Development (HLPF), which will be held in New York on July 10–19, 2023. Nature Water asked five experts about the challenges to meet the goals and where we need to go from here.

Transforming how we understand, value and manage water towards water security and resilience will accelerate progress in achieving the 2030 Agenda. On 22–24 March 2023, a unique United Nations (UN) Conference on water will be held, uniting the world for water. We reflect on this once-in-generation opportunity, and how it can spillover a just and sustainable transformation across all sectors and governance levels.

The United Nation 2023 Water Conference offers a critical opportunity to catalyse actions and innovations that bring increased water security to vulnerable communities across the globe. Researchers have an important role in supporting the delivery of needed on-the-ground impact, but their work must be informed by the priorities and necessities of Global South implementors.

This Perspective reviews key water-related goals and progress achieved since the first UN Water Conference in Mar del Plata (1977) and highlights three priorities for the second UN Water Conference in New York (2023).

A substudy nested within a double-blind cluster-randomized controlled trial in Bangladesh shows that drinking chlorinated water had relatively minor impacts on children’s gut microbiome development in this setting.

The health and non-health impacts of water collection and other water-related work should be monitored and considered in policies and programs to improve women’s lives.

Decentralized water treatment technologies could help in addressing global key water issues. This Perspective reviews the literature on the psychological determinants of acceptance, support and behaviour change related to decentralized water treatment technologies and proposes a user-focused theory of change to guide the promotion of these technologies.

The authors compared the performance of a range of rural water supply types during drought in Ethiopia. They show that prioritising access to groundwater via multiple improved water sources and technologies, such as hand-pumped and motorised boreholes, supported by monitoring and proactive operation and maintenance increases rural water supply resilience.

Local government investment in water infrastructure is associated with rural economic development in the United States. Through the use of interactional models, the economic benefits are shown to be ethnically and racially uneven.

Unaffordable water prices pose a threat to human health and well-being. A socio-hydrological modelling approach that integrates hydrology, water infrastructure, utility decision-making and household behaviour can be used to understand the impacts of droughts on household water affordability

SDG 6.3 targets to half the proportion of untreated wastewater discharged to the environment by 2030 will substantially improve water quality globally, but a high-resolution surface water quality model suggests key thresholds will still not be met in regions with limited existing wastewater treatment.

The importance of ensuring access to clean drinking water is manifested in UN Sustainable Development Goals. Here, a national-level assessment of tap-water safety shows spatial variations across China. The disparity is correlated with natural and anthropogenic factors and linked to public health-risk rates.

Poor access to safe drinking water is a major global sustainability issue. Solar disinfection provides a feasible solution. Here the authors examine the potential of five most typical types of this technology, revealing their unique challenges and opportunities.

Proper water and sanitation access remains an issue for many in the United States. Here the authors estimate and map the full scope of water hardship, including both incomplete plumbing and water quality across the country.

A new study considering data from 7603 households across 28 sites in 22 low- and middle-income countries show that inequality of household water security follows a Development Kuznets Curve.

Recognizing the importance of experiences with water insecurity in the context of food and nutrition is a powerful way to act on the Food and Agriculture Organization’s call to “take water action for food and be the change” on World Food Day.

Access to water and food and their effects on environmental and human health should be assessed and addressed together.

Solar-driven water evaporation shows great potentials for obtaining clean water. An integrated system based on clean water–energy–food with solar-desalination, power generation and crop irrigation functions is a valuable strategy consistent with sustainable development.

Water is the driving force of all nature; a more sustainable future can only be achieved by concerted actions on water starting now.

Anthropogenic pressures and climate change are altering water flows worldwide. Better understanding, new economic thinking and an international governance framework are needed to stave off catastrophe.

The UN’s 17 Sustainable Development Goals (SDGs) are highly interrelated. This study finds 319 interactions between SDGs for the case of water pollution in China. Results show that effective pollution control requires accounting for these interactions.

This paper quantifies global urban water scarcity in 2016 and 2050 and explores potential solutions. One third to nearly half of the global urban population is projected to face water scarcity problems.

The impacts of water scarcity depend on physical basin characteristics and global economic dynamics. Here, the authors show scenario assumptions can yield either highly positive or negative economic impacts due to water scarcity, and the drivers of these impacts are basin-specific and cannot be determined a priori.

Ecosystems that provide fresh water for cities also impact sediment flows, flood mitigation and hydropower provision. This Article looks at over 300 cities globally to gauge the interactions of natural ecosystems with built infrastructure.

Global climate change mitigation policies aim to reduce emissions, but can have unintended local consequences. Mitigation in the land sector could impact local water resources, along with food and energy in the Zambezi Watercourse and similar river basins.

There are big uncertainties in the contribution of irrigation to crop yields. Here, the authors use Bayesian model averaging to combine statistical and process-based models and quantify the contribution of irrigation for wheat and maize yields, finding that irrigation alone cannot close yield gaps for a large fraction of global rainfed agriculture.

Clean water is a fundamental resource, yet the economic impacts of pollution, drinking water availability, and greenhouse gas emissions from freshwaters are unknown. Here the authors combine models with economic assessments and find trillions of dollars in savings by mitigating lake methane emissions.

The planetary boundaries framework outlines a safe operating space for humanity according to key Earth system dynamics. This Perspective proposes the addition of a green water planetary boundary based on root-zone soil moisture and demonstrates that widespread green water modifications now present increasing risks to Earth system resilience.

South Asian agriculture depends on water from rains, meltwater and groundwater, but climate change impacts the timing of these water sources’ availability. Projections indicate that meltwater and groundwater will become more important and will need to offset reduced rainfall during drier years.

Pesticide pollution is a risk for two-thirds of agriculture land. A third of high-risk areas are in high-biodiversity regions and a fifth are in low- and lower-middle-income areas, according to environmental modelling combined with pesticide application data.

Water utilities worldwide are facing increasing challenges related to imbalances between water demand and resource availability. Market-based policy tools, such as water pricing and utility subsidy, can be used in combination with information dissemination to reduce residential water consumption.

It is critical to understand different drivers of regional hydroclimate change and to reduce uncertainty in future projections. This study disentangles the effects of CO₂ physiology and deforestation on projected precipitation, surface relative humidity and air temperature in Amazonia using multiple Coupled Model Intercomparison Project Phase 6 experiments.

This study showcases that balancing-oriented hydropower operation supporting variable renewable energy integration provides a more affordable and water-saving clean energy transition than the conventional peak-shaving-oriented operation.

Surface water quality is impacted by climate change and human activities. This study identifies Sub-Saharan Africa as a major future hotspot of surface water pollution by applying a high-resolution global surface water quality model up to 2100.

Climate change is not just about getting drier or getting wetter when it comes to water availability. We should work towards a more comprehensive process understanding of the water cycle that accounts for human actions.

Rivers are important reservoirs of plastic pollution. This study demonstrates that fluvial floods drive macroplastic transport and accumulation in rivers with unique observational evidence during the July 2021 flood along the Dutch Meuse River.

Although we know that microplastic is a huge contaminant of water resources, a connection between its source and its fate is largely missing. Combining a high-resolution microplastic release model with a fate model in rivers and lakes allows the prediction of masses of microplastics in each river section on a country level.

Managing water and climate in tandem would protect water resources, reduce disaster risks, lower greenhouse-gas emissions and assure equitable access.

The socio-political factors influencing societal responses to drought are often overlooked in risk assessments. Here, a social-environmental scenario that bridges natural and social sciences is used to analyse responses of a Southern African city to unprecedented drought.

As climate-induced shocks and stresses increasingly occupy media attention, funding, national and global policy, and technical practice are shifting towards alignment with the United Nations Framework Convention on Climate Change’s (UNFCCC’s) Paris Agreement and away from the more narrowly sectoral Sustainable Development Goals (SDGs). Water resilience is emerging as a critical delivery mechanism for the Paris Agreement as the importance of adaptation and resilience accelerates. The SDGs, in contrast, have been unable to make use of either water resources or climate resilience as enabling tools for cross-sectoral integration and development coherence.

Projections of terrestrial water storage (TWS)—the sum of all continental water—are key to water resource and drought estimates. A hydrological model ensemble predicts climate warming will more than double the land area and population exposed to extreme TWS drought by the late twenty-first century.

Climate change impacts precipitation patterns, and thus the risk for drought. Damages from drought in Europe will increase with losses more than €65 billion per year in a scenario without climate mitigation; keeping warming below 2 °C avoids most impacts.

Shanghai is a city facing the challenge for flood defence under climate change. This study proposes engineering solutions for mitigation flood risks in Shanghai by incorporating regret theory and decision science into the dynamic-adaptation-pathways framework.

Without targeted climate adaptation, impacts of climate change threaten achievement of all 169 SDG targets. Fuldauer et al. provide an actionable framework to assess these impacts and help systematically align national adaptation plans with the SDGs.

Adequate water availability is key to human and ecosystem sustainability. Here, the authors show that seasonally variable regimes become more variable, and the combined influence of seasonality and magnitude of climate variables will affect future water availability.

This work identifies the world’s most vulnerable basins to social and ecological impacts from freshwater stress and storage loss: a set of 168 hotspot basins for global prioritization that encompass 1.5 billion people, 17% of global food crops, 13% of global GDP, and hundreds of significant wetlands.

The development of hydropower offers a renewable energy source that can help reduce society’s dependence on fossil fuels. A global assessment of the unused profitable hydropower potential can be performed by incorporating strict constraints to identify hydropower station locations with reduced environmental and societal impacts.

A cross-scale analysis of paired-stressor effects on biological variables of European freshwater ecosystems shows that in 39% of cases, significant effects were limited to single stressors, with nutrient enrichment being the most important of these in lakes. Additive and interactive effects were similarly frequent (ca. 30% each), this frequency being independent of the spatial scale of analysis for lakes but increasing with scale for rivers.

Satellite imagery for the period 2000–2018 reveals that population growth was greater in flood-prone regions than elsewhere, thus exposing a greater proportion of the population to floods.

River floods have direct and indirect consequences for society, and can cause fatalities, displacement and economic loss. This Review examines the physical and socioeconomic causes and impacts of disastrous river flooding, and past and projected trends in their occurrence.

Water resources are threatened by human activities and climate variability. This Review discusses trends in water storage and availability and examines ways to enhance water-resource resilience through green and grey solutions.

Droughts pose a threat to water availability for food production, enhancing urban conflicts. This study explores the drought–conflict nexus by accounting for the effects of droughts on the food-security pillars of availability, economic access and stability.

In the context of the March 2023 United Nations (UN) Water Conference, this note urges the leaders of UN Member States to deliberate the waters they share.

The United Nations 2023 Water Conference is a unique opportunity to create momentum to combat the global water crisis.

The opinions and desires of young researchers and youth action groups should be considered when planning solutions to water-related challenges at local and global scales.

The Indus river basin in South Asia is water stressed, energy insecure and intensively farmed, and research on this region often lacks a systemic approach to the issues. This study shows how the path to development in the region could be made less costly and more environmentally friendly by fostering transboundary cooperation.

The Nile River system is faced with challenges including increasing water demands, political tensions, and future climate and socio-economic uncertainties. Cooperative adaptive management can help increase synergies, balance trade-offs and bring various benefits to riparian countries.

Academics, funders and publishers need to support interdisciplinary research processes in which social sciences are placed on an equal footing with the natural sciences and engineering.

Global groundwater resources are under strain, with cascading effects on producers, food and fibre production systems, communities and ecosystems. In this Perspective, the authors call for a major shift in research, extension and policy priorities to build polycentric governance capacity and strategic planning tools to sustain aquifer-dependent communities.

Hydropower dams in the Lower Mekong basin have profound impact on the riverine ecosystems. Here the authors use strategic dam planning and power system modelling to show that there are economically and technically feasible alternatives to these dams with solar energy and power trading.

The Grand Ethiopian Renaissance Dam will be hugely beneficial to Ethiopia, but has raised tensions with neighbouring countries that rely on flow from the Blue Nile. Sterl et al. present scenarios for dam operation coupled with solar and wind power generation that could mitigate some of these concerns.

A multi-objective optimization water–energy model explores the effect of dam re-operation strategies to minimize hydrological alterations in the Lower Mekong. Dam re-operation provides a feasible opportunity for the restoration of key elements of hydrological variability without hindering hydropower production.

While fears of ‘water wars’ have been publicized in recent years, this Article illustrates the complexities surrounding resource availability and socio-political dynamics that may induce, or prevent, conflicts over water in arid landscapes.