As subsoil moisture disappears floods and droughts will be more severe

As subsoil moisture disappears—due to factors such as drought, land use change, or climate warming—both floods and droughts generally become more severe and frequent.carbonbrief+3​

Why Subsoil Moisture Matters

Subsoil moisture acts as a buffer in the landscape, helping absorb, store, and gradually release water, which mitigates both extremes. When this buffer is depleted:preventionweb+1​

• Droughts worsen because the land is unable to retain enough water during dry periods, rapidly drying out the soil and vegetation.climateinstitute+1​

• Floods can become more intense because dry or degraded soils often lose permeability and become less able to absorb rainfall, leading to faster, greater surface runoff.consciousplanet+2​

Mechanisms for More Intense Extremes

• Runoff and Erosion: Degraded soils with little moisture cannot absorb heavy rains, causing higher rates of erosion and flash floods, especially after prolonged dry spells.pmc.ncbi.nlm.nih+1​

• Hydrological Feedback Loop: Low soil moisture increases land surface temperature, which further dries the soil and increases atmospheric demand for moisture, causing drought to intensify and persist.nature+1​

• Flood Magnitude and Timing: Changes in antecedent soil moisture alter how rainfall translates into river flow, with dry soils often producing erratic flood responses, while saturated soils can make floods much worse.frontiersin+1​

Examples and Regional Risks

• Healthy soil holds water and mitigates extremes, while damaged or drying soils accelerate both flood risk during storms and drought severity during rainless periods.consciousplanet+1​

• In regions experiencing long-term soil moisture decline, such as parts of Canada, this effect is contributing to more unpredictable water resource availability and amplifying the consequences of climate change.carbonbrief+1​

Implications for Water Management

• Protecting and restoring soil health is critical for moderating both drought and flood impacts under changing climate conditions.

• Understanding regional soil moisture changes is increasingly seen as vital for forecasting and managing droughts and floods.preventionweb+1​

In summary, declining subsoil moisture intensifies both floods and droughts by undermining the soil’s natural regulating functions, increasing risks for agriculture, water resources, and communities.climateinstitute+3​

1. https://www.carbonbrief.org/global-soil-moisture-in-permanent-decline-due-to-climate-change/
2. https://www.preventionweb.net/news/auburn-researcher-finds-soil-moisture-key-understanding-drought-flood-risks
3. https://consciousplanet.org/en/save-soil/news/soil-and-water-unravelling-the-nexus
4. https://climateinstitute.ca/news/fact-sheet-climate-change-and-drought/
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC8349632/
6. https://www.nature.com/articles/s41467-025-56109-0
7. https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2023.1285766/full
8. https://rmets.onlinelibrary.wiley.com/doi/10.1002/joc.70007
9. https://hess.copernicus.org/articles/29/2185/2025/
10. https://www.sciencedirect.com/science/article/pii/S0038071724000932
11. https://www.c2es.org/content/drought-and-climate-change/
12. https://www.sciencedirect.com/science/article/pii/S0341816223004691
13. https://www.bbc.com/news/articles/cy4dgp1p3p1o
14. https://www.un.org/en/climatechange/science/climate-issues/water
15. https://practical.engineering/blog/2023/9/5/o75wujpyzgaik4rqe7pebwkb8w7svt
16. https://www.reading.ac.uk/news/2025/Research-News/Heatwaves-could-worsen-as-soil-moisture-changes---study
17. https://www.nature.com/articles/s43247-025-02470-3
18. https://repository.library.noaa.gov/view/noaa/55434/noaa_55434_DS1.pdf
19. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023EF003987
20. https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-11/