Systems in depth

One section per system: its state at evidence close, its exposures and what the operational series will watch.

6 min read0 figures5 tables20 notesNR-SECTOR-WATER-GLOBAL-2026-BASELINE

Contents
  1. ·Edition home
  2. ·Executive summary
  3. 1Water is where the systems meet
  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
    1. 8.1 Water and energy
    2. 8.2 Water and food
    3. 8.3 Water and health
    4. 8.4 Water and nature
    5. 8.5 Water extremes and cities
  11. AMethodology
  12. BData appendix
  13. CReferences and record
  14. ·Complete edition, for print

8.1Water and energy

Energy uses water and water uses energy. Hydropower and thermal cooling make power supply sensitive to drought and heat; pumping, treatment and desalination make water supply sensitive to energy prices.

≈10%

of withdrawals for energy production14

≈415TWh

used by data centres, 202413

2022analogue

drought cut hydro and cooling in Europe and China

Table 8.1State at baseline
ComponentStateEvidenceStatus
Hydropoweroutput falls with low flows and storage514Reported
Thermal coolingcurtailment when water is scarce or too warm14Reported
Water for computecooling demand rising; volumes not consolidated13Expert input
Energy for waterpumping, treatment and desalination14Reported

Couplings

  • WAT → ENE hydro and cooling
  • ENE → WAT pumping and desalination
  • AIC → WAT data-centre cooling

Evidence to bind in 2027

  • data-centre water use by region
  • hydro exposure to multi-year drought

Related editions

  • GLB Global Systems
  • GS-02 Energy
  • GS-03 Food
  • GS-04 Health
  • GS-11 Biodiversity
  • SR-07 Food–water–energy

8.2Water and food

Food is the largest user of water. Irrigated agriculture depends on groundwater and on glacier- and snow-fed rivers, both of which are declining in key regions.

≈70%

of withdrawals for agriculture2

≈25%

of irrigation water from groundwater4

673million

people facing hunger, 202416

Table 8.2State at baseline
ComponentStateEvidenceStatus
Irrigationabout 70% of withdrawals215Reported
Groundwaterdeclines accelerating in many irrigated aquifers20Reported
Rain-fed yieldsexposed to drought and heat12Reported
Tradefood trade moves virtual water between basins23Inferred

Couplings

  • WAT → FOO irrigation and rain-fed yields
  • FOO → WAT withdrawals and pollution
  • FOO → TRD price transmission

Evidence to bind in 2027

  • aquifer–crop dependence by region
  • concurrent drought across breadbaskets41

Related editions

  • GLB Global Systems
  • GS-02 Energy
  • GS-03 Food
  • GS-04 Health
  • GS-11 Biodiversity
  • SR-07 Food–water–energy

8.3Water and health

Unsafe water, sanitation and hygiene remain a leading preventable cause of death. Floods spread disease; drought concentrates contaminants and strains hygiene.

1.4million

WASH-attributable deaths, 201938

2.0billion

without basic hygiene, 20221

3.5billion

without safely managed sanitation1

Table 8.3State at baseline
ComponentStateEvidenceStatus
Diarrhoeal diseasemost WASH-attributable deaths38Reported
Floodscontamination and disease after events12Reported
Droughtwater quality and hygiene strain12Inferred
Health facilitiesmany lack basic water services1Reported

Couplings

  • WAT → HLT access and quality
  • CLI → WAT → HLT flood and drought
  • ENE → WAT → HLT treatment

Evidence to bind in 2027

  • water quality in fast-growing cities
  • WASH in health facilities

Related editions

  • GLB Global Systems
  • GS-02 Energy
  • GS-03 Food
  • GS-04 Health
  • GS-11 Biodiversity
  • SR-07 Food–water–energy

8.4Water and nature

Freshwater ecosystems regulate floods, filter water and sustain fisheries, and they are declining faster than any other realm.

−85%

freshwater wildlife, 1970–202017

22%

of wetland area lost since 197018

2030target

restore degraded ecosystems30

Table 8.4State at baseline
ComponentStateEvidenceStatus
Speciesfreshwater populations declining fastest17Reported
Wetlandsmore than a fifth lost since 197018Reported
Flowsdams and withdrawals alter river regimes12Reported
Servicesflood regulation and filtration weakened47Inferred

Couplings

  • BIO → WAT regulation and filtration
  • WAT → BIO flows and quality
  • FOO → WAT → BIO withdrawals

Evidence to bind in 2027

  • ecosystem condition of major rivers
  • restoration progress against 2030 targets

Related editions

  • GLB Global Systems
  • GS-02 Energy
  • GS-03 Food
  • GS-04 Health
  • GS-11 Biodiversity
  • SR-07 Food–water–energy

8.5Water extremes and cities

Floods are among the costliest perils, and droughts strain fast-growing cities. Urban water systems sit where extremes and demand meet.

166US$ bn

flood, storm and fire losses, 20257

2018analogue

Cape Town supply crisis

108countries

with multi-hazard early warning, 202433

Table 8.5State at baseline
ComponentStateEvidenceStatus
Floodsamong the costliest and most frequent perils724Reported
Urban droughtsupply crises in large cities2Reported
Early warningflood warning demonstrated in real events33Reported
Protection gapflood losses often uninsured7Inferred

Couplings

  • CLI → WAT → cities
  • WAT → FIN uninsured flood losses
  • WAT → HLT after floods

Evidence to bind in 2027

  • flood loss and cover by region
  • urban drought preparedness

Related editions

  • GLB Global Systems
  • GS-02 Energy
  • GS-03 Food
  • GS-04 Health
  • GS-11 Biodiversity
  • SR-07 Food–water–energy

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. 14International Energy Agency (ed.), Water–Energy Nexus. World Energy Outlook 2016 Special Report. IEA, Paris, 2016.back
  2. 13International Energy Agency (ed.), Energy and AI. World Energy Outlook Special Report. IEA, Paris, 2025.back
  3. 5WMO (ed.), State of Global Water Resources 2023. World Meteorological Organization, Geneva, 2024.back
  4. 2UNESCO World Water Assessment Programme (ed.), The United Nations World Water Development Report 2024: Water for Prosperity and Peace. UNESCO, Paris, 2024.back
  5. 4UNESCO World Water Assessment Programme (ed.), The United Nations World Water Development Report 2022: Groundwater, Making the Invisible Visible. UNESCO, Paris, 2022.back
  6. 16FAO, IFAD, UNICEF, WFP and WHO (eds.), The State of Food Security and Nutrition in the World 2025. FAO, Rome, 2025.back
  7. 15FAO (ed.), The State of the World’s Land and Water Resources for Food and Agriculture 2021: Systems at Breaking Point. FAO, Rome, 2021.back
  8. 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
  9. 12R. Caretta, A. Mukherji et al., “Water,” in H.-O. Pörtner et al. (eds.), Climate Change 2022: Impacts, Adaptation and Vulnerability, pp. 551–712. Cambridge University Press, Cambridge, 2022.back
  10. 23A. Y. Hoekstra and M. M. Mekonnen, “The water footprint of humanity,” Proceedings of the National Academy of Sciences, vol. 109, pp. 3232–3237, 2012.back
  11. 41F. Gaupp, J. Hall, S. Hochrainer-Stigler and S. Dadson, “Changing risks of simultaneous global breadbasket failure,” Nature Climate Change, vol. 10, pp. 54–57, 2020.back
  12. 38WHO (ed.), Burden of Disease Attributable to Unsafe Drinking-water, Sanitation and Hygiene: 2019 Update. WHO, Geneva, 2023.back
  13. 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
  14. 17WWF (ed.), Living Planet Report 2024: A System in Peril. WWF, Gland, 2024.back
  15. 18Ramsar Convention Secretariat (ed.), Global Wetland Outlook 2025. Ramsar Convention Secretariat, Gland, 2025.back
  16. 30Convention on Biological Diversity (ed.), Kunming-Montreal Global Biodiversity Framework, Decision 15/4. CBD Secretariat, Montreal, 2022.back
  17. 47IFRS Foundation (ed.), IFRS S2 Climate-related Disclosures. International Sustainability Standards Board, London, 2023.back
  18. 7Munich Re (ed.), Natural disasters in 2025: NatCatSERVICE full-year figures. Munich Re, Munich, January 2026.back
  19. 33WMO and UNDRR (eds.), Global Status of Multi-Hazard Early Warning Systems 2024. WMO and UNDRR, Geneva, 2024.back
  20. 24UNDRR (ed.), Global Assessment Report on Disaster Risk Reduction 2025: Resilience Pays. UNDRR, Geneva, 2025.back

Cite this chapter

Valadbaygi, S. (Ed.). (2026). Chapter 8: Systems in depth. 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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