Skip to Content

Floods

Texas is no stranger to flooding, but climate change is making these natural disasters more frequent and severe across the entire state. Flooding is easily one of the worst and most deadly global natural disasters, responsible for millions of deaths over the last century1. Floods also cause large amounts of long-term mental trauma, and the damage to infrastructure can take years and billions of dollars to rebuild2-4. Severe flood events are shown to disproportionally affect at-risk and socially vulnerable communities, which adds complexity to implementing adaptation and mitigation strategies5,6.

Floods can be categorized three ways: (1) river flooding when intense rainfall causes the water level to exceed the bank’s capacity, (2) surface (flash) flooding when the ground cannot drain rainfall faster than it accumulates, and (3) coastal flooding where high winds from hurricanes blow seawater inland in surges7. All three types of floods are known to occur in Texas, most significantly impacting urban areas with extensive impervious surfaces that preclude infiltration, especially those along the Gulf Coast1,8. Over 1,000 square miles in Texas are below 5 feet of the tideline without any barrier protection, with 2,400 square miles being below 10 feet, exposing over 365,000 people directly to coastal floods9.

Hurricane Harvey in 2017 was the most intense rainfall event in the United States on record, causing over 100 deaths and $125 billion in damages10. Warmer temperatures from climate change made floods from Hurricane Harvey 15 percent more intense and three times as likely to happen11,12. From 1950 to 2005, Texas had the largest number of inland flood-related deaths in the United States13. The largest number of tidal floods along the Texas coastline were recorded in 202014

The occurrence of extreme rainfall events in Texas is projected to continue becoming more intense and frequent1,15. As average air temperatures increase, the atmosphere’s capacity to hold water vapor rises by 7 percent per 1°C (1.8 °F), so more rain falls in the same period16. This increase in rainfall intensity puts drainage and flood management infrastructure under strain7,17.

Rising sea levels increase storm surges from hurricanes, causing severe floods even if the hurricane fails to make landfall15,8. The increased frequency of extreme rainfall events is expected to make urban floods in Texas 30 to 50 percent more likely to happen in the next two decades than in the last half of the 20th century15,18. Models exploring a future with continued greenhouse gas emissions project a significant intensification of inland surges1. Coastal floods are 33 percent more likely to have a 10 percent chance of occurring during any year by 20501,19.

Flood occurrence and magnitude for inland Texas rivers are expected to regionally increase over time as greater rainfall intensity outweighs drier soils with higher water capacities15,20. Urban expansion along riparian corridors may elevate flood risk depending on infrastructure design, but coastal areas will be at an overall much greater risk8,17,20. The United States faces a 26 percent greater risk of flooding over the next 30 years6. As populations in Texas continue to grow and urban areas expand, more people will be threatened by flooding, especially as coastal areas are desirable to live in and more affordable land often corresponds to lower floodplains with greater risk20-23.

Floods are complex as they depend on weather conditions and location, surface position, and infrastructure design. The best way to prepare for flood events is to learn more about them and what flood risk zone you live in. Explore more about flood risk and climate change through the resources below.

Updated Flood Damage Risk Maps (The Conversation)

Vulnerability and Adaptation to Climate Change: An Assessment of the Texas Mid-Coast

References

  1. Kloesel, K., B. Bartush, J. Banner, D. Brown, J. Lemery, X. Lin, C. Loeffler, G. McManus, and others 2018. Chapter 23: Southern great plains. Impacts, risks, and adaptation in the United States: The fourth national climate assessment, volume II. U.S. Global Change Research Program.
  2. Verger, P., M. Rotily, C. Hunault, J. Brenot, E. Baruffol, and D. Bard. 2003. Assessment of exposure to a flood disaster in a mental-health study. Journal of Exposure Science & Environmental Epidemiology 13. Nature Publishing Group: 436–442.
  3. Fernandez, A., J. Black, M. Jones, L. Wilson, L. Salvador-Carulla, T. Astell-Burt, and D. Black. 2015. Flooding and mental health: a systematic mapping review. PloS one 10. Public Library of Science San Francisco, CA USA: e0119929.
  4. Fan, Q., K. Fisher-Vanden, and H. A. Klaiber. 2018. Climate change, migration, and regional economic impacts in the United States. Journal of the Association of Environmental and Resource Economists 5. University of Chicago Press Chicago, IL: 643–671.
  5. Hardy, R. D., R. A. Milligan, and N. Heynen. 2017. Racial coastal formation: The environmental injustice of colorblind adaptation planning for sea-level rise. Geoforum 87. Elsevier: 62–72.
  6. Wing, O. E., W. Lehman, P. D. Bates, C. C. Sampson, N. Quinn, A. M. Smith, J. C. Neal, J. R. Porter, and others 2022. Inequitable patterns of US flood risk in the Anthropocene. Nature Climate Change. Nature Publishing Group: 1–7.
  7. Berghuijs, W. R., R. A. Woods, C. J. Hutton, and M. Sivapalan. 2016. Dominant flood generating mechanisms across the United States. Geophysical Research Letters 43. Wiley Online Library: 4382–4390.
  8. Li, X., G. Zhao, J. Nielsen-Gammon, J. Salazar, M. Wigmosta, N. Sun, D. Judi, and H. Gao. 2020. Impacts of urbanization, antecedent rainfall event, and cyclone tracks on extreme floods at Houston reservoirs during Hurricane Harvey. Environmental Research Letters 15. IOP Publishing: 124012.
  9. Hauer, M. E., J. M. Evans, and D. R. Mishra. 2016. Millions projected to be at risk from sea-level rise in the continental United States. Nature Climate Change 6. Nature Publishing Group: 691–695.
  10. Blake, E. S., and D. A. Zelinsky. 2018. Hurricane Harvey (AL092017). National Hurricane Center tropical cyclone report: 77. https://www.nhc.noaa.gov/data/tcr/AL092017_Harvey.pdf.
  11. Van Oldenborgh, G. J., K. Van Der Wiel, A. Sebastian, R. Singh, J. Arrighi, F. Otto, K. Haustein, S. Li, and others 2017. Attribution of extreme rainfall from Hurricane Harvey, August 2017. Environmental Research Letters 12. IOP Publishing: 124009.
  12. Sebastian, A., A. Gori, R. B. Blessing, K. van der Wiel, and B. Bass. 2019. Disentangling the impacts of human and environmental change on catchment response during Hurricane Harvey. Environmental Research Letters 14. IOP Publishing: 124023.
  13. Ashley, S. T., and W. S. Ashley. 2008. Flood fatalities in the United States. Journal of Applied Meteorology and Climatology 47. American Meteorological Society: 805–818.
  14. Runkle, J., K. E. Kunkel, J. Nielson-Gammon, R. Frankson, S. M. Champion, B. C. Stewart, L. Romolo, and W. Sweet. 2022. Texas State Climate Summary 2022. Vol. 5. Silver Spring, MD.
  15. Nielsen-Gammon, J., S. Holman, A. Buley, S. Jorgensen, J. Escobedo, C. Ott, J. Dedrick, and A. Van Fleet. 2021. Assessment of Historic and Future Trends of Extreme Weather in Texas, 1900-2036. OSC-202101. Texas A&M University.
  16. IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press. In Press.
  17. Qing, Y., S. Wang, B. Zhang, and Y. Wang. 2020. Ultra-high resolution regional climate projections for assessing changes in hydrological extremes and underlying uncertainties. Climate Dynamics 55. Springer: 2031–2051.
  18. Zhao, G., H. Gao, and L. Cuo. 2016. Effects of urbanization and climate change on peak flows over the San Antonio River Basin, Texas. Journal of Hydrometeorology 17: 2371–2389.
  19. Villarini, G., and J. A. Smith. 2013. Flooding in Texas: Examination of temporal changes and impacts of tropical cyclones. JAWRA Journal of the American Water Resources Association 49. Wiley Online Library: 825–837.
  20. Mishra, A. K., V. P. Singh, and M. Özger. 2011. Seasonal streamflow extremes in Texas river basins: uncertainty, trends, and teleconnections. Journal of Geophysical Research: Atmospheres 116. Wiley Online Library.
  21. Berg, M. 2018. Peak flow trends highlight emerging urban flooding hotspots in Texas. Texas Water J. 9: 18–29.
  22. Johnson, K. A., O. E. Wing, P. D. Bates, J. Fargione, T. Kroeger, W. D. Larson, C. C. Sampson, and A. M. Smith. 2020. A benefit–cost analysis of floodplain land acquisition for US flood damage reduction. Nature Sustainability 3. Nature Publishing Group: 56–62.
  23. EPA. 2021. Climate Change and Social Vulnerability in the United States: A Focus on Six Impacts. EPA 430-R-21-003. U.S. Environmental Protection Agency.