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Dry year with low reservoirs and low river flows

A conditional statement under stated assumptions, never a prediction.

3 min read0 figures0 tables4 notesNR-COUNTRY-CHE-2026-BASELINE

Contents
  1. ·Edition home
  2. ·Executive summary
  3. 1Switzerland’s risk starts in the mountains and runs through water
  4. 2Key findings
  5. 3Systems and sectors at baseline
  6. 4Risks and capability
  7. 5Dry year with low reservoirs and low river flows
    1. 5.1 Assumptions
    2. 5.2 The cascade, step by step
    3. 5.3 The scenario as a table of steps
  8. 6Readings from the other desks
  9. 7The 2027 agenda
  10. 8Systems in depth
  11. AMethodology
  12. BData appendix
  13. CReferences and record
  14. ·Complete edition, for print

5.1Assumptions

Scenario SCN-CHE-DRT-01: what is assumed, and what is held constant.

Baseline
the 2026 reference state in this edition
Drivers
a snow-poor winter followed by a dry spring and summer, with low reservoir fill and low Rhine flow into the autumn
Analogues
the 2026 drought19208; summer 2003 Rhine flow at Basel20
Interventions
none modelled; the specification describes the unmitigated case
Run state
narrative specification; quantified Foundry run scheduled for Q1 2027

5.2The cascade, step by step

  1. 1

    CLI → WAT

    snow deficit and dry spring lower rivers, lakes and groundwater

    2026

  2. 2

    WAT → ENE

    hydropower falls; 2025 output was down 22.5%

    2025 · 2026

  3. 3

    ENE → FIN

    import needs and exposure to foreign supply rise in winter

    not bound

  4. 4

    WAT → FOO

    pastures and farm liquidity strained; CHF 54 million in loans offered

    2026

  5. 5

    CLI → BIO

    forests and streams under stress; dead trees were 7.2% to 15.4% of trees by region

    2018–202226

  6. 6

    CLI → HLT

    hot, dry summers raise heat deaths

    2022–2024

5.3The scenario as a table of steps

How the shock in scenario SCN-CHE-DRT-01 would travel through Switzerland’s coupled systems, step by step, under the assumptions the edition states.

StepWhat happensSource
01 Climate to waterSnow deficit and dry spring lower rivers, lakes and groundwater. Analogue or source: 2026.Edition CHE, scenario SCN-CHE-DRT-01, step 1
02 Water to energyHydropower falls; 2025 output was down 22.5%. Analogue or source: 2025 · 2026.Edition CHE, scenario SCN-CHE-DRT-01, step 2
03 Energy to financeImport needs and exposure to foreign supply rise in winter. Analogue or source: not bound.Edition CHE, scenario SCN-CHE-DRT-01, step 3
04 Water to foodPastures and farm liquidity strained; CHF 54 million in loans offered. Analogue or source: 2026.Edition CHE, scenario SCN-CHE-DRT-01, step 4
05 Climate to biodiversityForests and streams under stress; dead trees were 7.2% to 15.4% of trees by region. Analogue or source: 2018–2022 [26].Edition CHE, scenario SCN-CHE-DRT-01, step 5
06 Climate to healthHot, dry summers raise heat deaths. Analogue or source: 2022–2024.Edition CHE, scenario SCN-CHE-DRT-01, step 6

A teaching model of a conditional scenario under the edition’s stated assumptions: not a forecast, not a prediction and not a warning. Sources: Switzerland 2026, scenario SCN-CHE-DRT-01 (2026); Switzerland 2026, references (NR-CIT-1) (2026).

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. 19FOEN (ed.), statement to Keystone-SDA on drought: historic lows at eleven stations in July 2026; about one-fifth of stations at a record low for the period from 1 April to 31 July. Published by blue News, 13 August 2026. Observation year 2026. https://www.bluewin.ch/en/news/drought-causes-swiss-water-levels-to-drop-to-record-lows-li.3561545, accessed 2026-11-03. Press report of a federal statement.back
  2. 20L. Jorio (ed.), “Drought in Switzerland: Europe’s water tower runs dry” (Lake Zurich lowest since records began in 1951 on 19 August 2026; Lake Constance 394.97 m on 11 August, 27 cm below the previous 1991–2020 low; Rhine at Basel in July below summer 2003). swissinfo.ch, 21 August 2026. Observation year 2026. https://www.swissinfo.ch/eng/climate-adaptation/drought-in-switzerland-europes-water-tower-runs-dry/91913797, accessed 2026-11-03. Press report; FOEN is the cited data source.back
  3. 8SRF and swissinfo.ch (eds.), “Swiss reservoir water levels lowest in 20 years” (46% full, 16.4 points below the 20-year average, per the SFOE weekly report; reservoirs cover about 20% of winter-half demand). swissinfo.ch, 17 July 2026. Observation year 2026. https://www.swissinfo.ch/eng/climate-adaptation/swiss-reservoir-water-levels-lowest-in-20-years/91760665, accessed 2026-11-03. Press report of SFOE figures.back
  4. 26FOEN and WSL (eds.), Swiss National Forest Inventory, fifth survey (LFI5), interim results for survey years 2018–2022 (dead trees 7.2% to 15.4% of trees by region). Bern and Birmensdorf, 9 September 2024. Observation years 2018–2022. https://www.bafu.admin.ch/de/schweizerisches-landesforstinventar-lfi, accessed 2026-11-03.back

Cite this chapter

Valadbaygi, S. (Ed.). (2026). Chapter 5: Dry year with low reservoirs and low river flows. In Switzerland Systems Risk and Resilience Report 2026: The State of Switzerland’s Interdependent Systems (Baseline Edition 2026, Report No. NR-COUNTRY-CHE-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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Sector signature

The sectors behind Switzerland.

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

Select corners · hover lines6 / 15 relations

Context

Hydropower reservoir

A dam stores water for power and flood control, and reshapes the river’s sediment, fish passage and wetlands downstream.

W · E · I · F · H · B

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

Strongest relations in play

  • Energy → Infrastructure · power for transport and telecoms0.8
  • Water → Energy · cooling water and hydropower0.6
  • Water → Biodiversity · environmental flows0.6
  • Infrastructure → Water · pipes, dams and treatment works0.6
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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