Water is where the systems meet

Part I describes systems and their couplings. It ranks no country or basin and assesses no utility or authority.

7 min read2 figures2 tables18 notesNR-SECTOR-WATER-GLOBAL-2026-BASELINE

Contents
  1. ·Edition home
  2. ·Executive summary
  3. 1Water is where the systems meet
    1. 1.1 The questions this part answers
    2. 1.2 The argument
    3. 1.3 Twenty couplings between five systems
    4. 1.4 Reinforcing loops
  4. 2Key findings
  5. 3Systems and sectors at baseline
  6. 4Risks and capability
  7. 5Multi-basin drought under heat
  8. 6Lenses and readings
  9. 7The 2027 agenda
  10. 8Systems in depth
  11. AMethodology
  12. BData appendix
  13. CReferences and record
  14. ·Complete edition, for print

1.1The questions this part answers

Key questions

  • Where is water risk concentrated, in access, scarcity, groundwater or extremes?
  • Which couplings carry water shocks into energy, food and health?
  • Which water capabilities hold under compound stress?
  • What must basin evidence measure first in 2027?

In this part

  • Narrative
  • Headline finding
  • Lead figure
  • Five coupling chapters
  • Twelve-domain reading
  • Sector screens
  • Dependency matrix
  • Risk objects
  • Capability ladder
  • Scenario
  • Three lenses
  • Portfolio

1.2The argument

Water is usually reported as a sector: utilities, irrigation, flood defence. The 2026 evidence reads it as the medium through which almost every other system’s risk travels. Agriculture takes about 70% of withdrawals2, thermal power plants and hydropower depend on flows14, disease follows unsafe water38, and freshwater ecosystems are declining faster than any other realm17.

Access is still unfinished. In 2022, 2.2 billion people lacked safely managed drinking water, 3.5 billion lacked safely managed sanitation and 2 billion lacked basic hygiene facilities at home1. At current rates the world will not reach the 2030 targets for water and sanitation10. Unsafe water, sanitation and hygiene were linked to about 1.4 million deaths in 2019, most of them from diarrhoeal disease38.

Scarcity is now a seasonal condition for half of humanity. Roughly half of the world’s people experience severe water scarcity for at least part of the year222, and global water use has risen by about 1% a year for four decades3. About 739 million children live in areas of high or extremely high water scarcity39.

The water cycle itself is shifting. 2023 was the driest year for global rivers in 33 years, and glaciers lost more than 600 gigatonnes of water, the largest loss in five decades5. Glacier mass loss has accelerated this century21, and groundwater declines have accelerated in many of the world’s aquifers20. Groundwater supplies about half of domestic water and a quarter of irrigation4.

Extremes carry the costs. Floods, severe storms and wildfires caused US$166 billion of the US$224 billion in natural-disaster losses in 20257. Drought is less visible in loss data, but it moves through food prices, hydropower output and public budgets. Water scarcity could cost some regions up to 6% of GDP by 205035.

Governance is shared and incomplete. 153 countries share transboundary rivers, lakes or aquifers, but most do not yet have operational arrangements covering all of them9. The December 2026 UN Water Conference is the first chance since 2023 to set a common direction43.

This edition therefore reads water as the coupling layer of the WEFH+B system. The matrix, risk objects, capability ladder and scenario that follow ask the same two questions: where does a water shock travel next, and who holds the capability to stop it?

Figure 1.1How far is the world from universal water, sanitation and hygiene? People without services, 2022 (billion)

More people lack safe sanitation than safe drinking water. All three gaps are concentrated in the same places, low-income, rural and fragile settings, so they compound each other’s health effects1.

ItemBar, scaled to the largest valueValue
Safely managed sanitation3.5
Safely managed drinking water2.2
Basic hygiene2

Source: as cited in the note to this figure. Year 2022.

Figure ID FIG-SECTOR-WATER-GLOBAL-2026-BASELINE-01-003

1.4million

WASH-attributable deaths, 201938

739million

children in high water scarcity39

≈50%

of people with severe seasonal scarcity2

2030target

universal access under SDG 629

1.3Twenty couplings between five systems

The water-centred matrix types the twenty couplings between the five core systems, read for their water content. Strengths are Nexus estimates from the cited assessments and analogue events; they set the graph that basin evidence will test in 2027.

Figure 1.2Couplings between the five systems

Each line is one coupling from one system to another, drawn by the strength the edition assigns. Strengths are Nexus estimates from the cited evidence and analogue events.

  • Strong
  • Moderate
  • Weak

Source: this edition’s coupling matrix (Table 1.1); status Estimated.

Table 1.1Coupling matrix: from the row system to the column system
From, toWATENEFOOHLTBIO
WAT Water·STRONG
hydro · thermal cooling		STRONG
irrigation · rain-fed yield		STRONG
safe water · sanitation		STRONG
flows · wetlands
ENE EnergyMODERATE
pumping · treatment · desalination		·STRONG
fuel · fertiliser · cold chain		STRONG
air pollution · cooling		MODERATE
land use · mining
FOO FoodSTRONG
≈70% of withdrawals		WEAK
bioenergy feedstock		·STRONG
nutrition · food safety		STRONG
land conversion
HLT HealthWEAK
workforce		WEAK
workforce		MODERATE
labour · disease		·WEAK
residues
BIO BiodiversitySTRONG
regulation · filtration		MODERATE
biomass · hydrology		STRONG
pollination · soils		MODERATE
zoonoses · medicines		·
Strength: strong, moderate or weak; a Nexus estimate (status Estimated) from cited evidence and analogue events. The scale is defined in Annex A.

Transmission paths

  1. 01

    CLI → WAT → ENE

    Drought lowers reservoirs and warms cooling water; hydro and thermal output fall.

    Reported 2022 drought, Europe and China

  2. 02

    CLI → WAT → FOO

    Multi-basin drought cuts irrigated and rain-fed yields.

    Inferred 2010–2012 droughts

  3. 03

    WAT → HLT

    Floods contaminate supplies and spread disease.

    Reported major floods since 2010

  4. 04

    FOO → WAT → BIO

    Irrigation expansion depletes aquifers and river flows.

    Reported aquifer declines20

  5. 05

    WAT → FIN

    Flood losses fall on the uninsured and on public budgets.

    Reported 2025 losses7

1.4Reinforcing loops

A shock entering either system of a loop can return amplified through the other.

Table 1.2Pairs of systems where both directions are rated strong
LoopFirst directionSecond direction
WAT and FOOWater to food: irrigation · rain-fed yieldFood to water: ≈70% of withdrawals
WAT and BIOWater to biodiversity: flows · wetlandsBiodiversity to water: regulation · filtration
FOO and BIOFood to biodiversity: land conversionBiodiversity to food: pollination · soils
A causal-loop reading of the matrix (Sterman, Business Dynamics, 2000): structural, from estimated strengths, not a measured feedback.

Notes

Numbers are the edition’s reference numbers, so a note reads the same in every chapter. The full list, with every source and its licence, is in Annex C. Annex C, references

  1. 2UNESCO World Water Assessment Programme (ed.), The United Nations World Water Development Report 2024: Water for Prosperity and Peace. UNESCO, Paris, 2024.back
  2. 14International Energy Agency (ed.), Water–Energy Nexus. World Energy Outlook 2016 Special Report. IEA, Paris, 2016.back
  3. 38WHO (ed.), Burden of Disease Attributable to Unsafe Drinking-water, Sanitation and Hygiene: 2019 Update. WHO, Geneva, 2023.back
  4. 17WWF (ed.), Living Planet Report 2024: A System in Peril. WWF, Gland, 2024.back
  5. 1WHO and UNICEF (eds.), Progress on Household Drinking Water, Sanitation and Hygiene 2000–2022: Special Focus on Gender. Joint Monitoring Programme, New York and Geneva, 2023.back
  6. 10UN-Water (ed.), Blueprint for Acceleration: Sustainable Development Goal 6 Synthesis Report on Water and Sanitation 2023. United Nations, Geneva, 2023.back
  7. 22M. M. Mekonnen and A. Y. Hoekstra, “Four billion people facing severe water scarcity,” Science Advances, vol. 2, e1500323, 2016.back
  8. 3UNESCO World Water Assessment Programme (ed.), The United Nations World Water Development Report 2023: Partnerships and Cooperation for Water. UNESCO, Paris, 2023.back
  9. 39UNICEF (ed.), The Climate-Changed Child: A Children’s Climate Risk Index Supplement. UNICEF, New York, 2023.back
  10. 5WMO (ed.), State of Global Water Resources 2023. World Meteorological Organization, Geneva, 2024.back
  11. 21R. Hugonnet, R. McNabb, E. Berthier et al., “Accelerated global glacier mass loss in the early twenty-first century,” Nature, vol. 592, pp. 726–731, 2021.back
  12. 20S. Jasechko, H. Seybold, D. Perrone et al., “Rapid groundwater decline and some cases of recovery in aquifers globally,” Nature, vol. 625, pp. 715–721, 2024.back
  13. 4UNESCO World Water Assessment Programme (ed.), The United Nations World Water Development Report 2022: Groundwater, Making the Invisible Visible. UNESCO, Paris, 2022.back
  14. 7Munich Re (ed.), Natural disasters in 2025: NatCatSERVICE full-year figures. Munich Re, Munich, January 2026.back
  15. 35World Bank (ed.), High and Dry: Climate Change, Water, and the Economy. World Bank, Washington, DC, 2016.back
  16. 9UNECE and UNESCO (eds.), Progress on Transboundary Water Cooperation: Global Status of SDG Indicator 6.5.2 and Acceleration Needs, 2024. United Nations, Geneva and Paris, 2024.back
  17. 43S. Valadbaygi (ed.), Reports, The Foundational Edition, Volumes I and II. Reports series, Edition 2026–2030, V1.0. The Global Centre for Risk and Innovation (GCRI) for the Nexus Consortium, Toronto, 2026.back
  18. 29United Nations General Assembly (ed.), Transforming our World: The 2030 Agenda for Sustainable Development, resolution 70/1. United Nations, New York, 2015.back

Cite this chapter

Valadbaygi, S. (Ed.). (2026). Chapter 1: Water is where the systems meet. In Global Water Risk and Resilience Report 2026: The State of the World’s Water System (Baseline Edition 2026, Report No. NR-SECTOR-WATER-GLOBAL-2026-BASELINE) [Draft under review]. The Global Centre for Risk and Innovation (GCRI).

Every citation form of the whole report, BibTeX and RIS included, is on the edition home. Cite this report

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The sectors behind Global Water.

A reading aid: the sectors the findings run through and how strongly they depend on each other.

Select corners · hover lines6 / 15 relations

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Water and its partners

Water gives irrigation to food (0.8), cooling water and hydropower to energy (0.6) and environmental flows to biodiversity (0.6).

W · E · I · F · H · B

Sectors
4 of 6
Relations
6 of 15
Coupling
0.43 share of total

Strongest relations in play

  • Food → Biodiversity · land conversion0.6
  • Water → Energy · cooling water and hydropower0.6
  • Water → Food · irrigation0.8
  • Water → Biodiversity · environmental flows0.6
Teaching values for a typical city-region, not measurements for any place. Coupling is the summed strength of the relations in play, as a share of all fifteen.
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