Groundwater Availability

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Summary

  • Despite increasing precipitation, land surfaces in the Great Lakes region are expected to become drier overall due to rising temperatures and evaporation rates.
  • More frequent droughts could affect soil moisture, surface waters, and groundwater supply. 
  • The seasonal distribution of water availability will likely change. Warmer temperatures may lead to more winter rain and earlier peak streamflows.

Groundwater (i.e., water found underground) is a critical source of water in the Great Lakes region: there is as much groundwater as there is water in Lake Michigan. 1 Though counterintuitive, some areas may experience reduced water supplies during summer months, even as annual total precipitation is expected to increase throughout the region. As temperatures rise, increasing evaporation may outpace increases in precipitation and elevate drought risk, particularly in areas that are already susceptible. 2 While decreases in summer groundwater supply are predicted overall, model projections of water availability and groundwater recharge (i.e., downward movement of water from the surface to replenish groundwater) vary widely on the timing, magnitude, and location of such changes. 3 4

An image of a crop irrigation system.

Groundwater Supply and Soil Moisture

Higher temperatures and evaporation rates decrease soil moisture and groundwater supply. 5 6 7 8  9 Parts of the region could see as much as a 30-percent decrease in soil moisture that would be strongest in summer, when groundwater recharge could be decreased most severely. More low-flow periods and droughts will become more likely. 10 11 12

Water Usage Conflicts

Reduced water availability could create greater disputes over limited water resources, as has happened in other parts of the United States, and responding to changes in water supply and demand distribution would be costly. 13 For example, some projections suggest Minnesota could suffer a loss of wetlands from increased evapotranspiration. In that case, diminished water supplies would have to be shared more heavily between human use and wetland protection. 14 

Surface Runoff

Runoff may become flashier (i.e., high volume amounts in short periods of time, rather than spread out over a longer period) and more sporadic, decreasing at times due to less soil moisture and groundwater, but increasing at other times due to more intense precipitation. 15 This carries significant implications for public health, water quality, and marine wildlife.

More intense precipitation events can lead to increased transport of pathogens that cause gastrointestinal illness into drinking-water sources. This puts populations that rely on untreated groundwater (such as smaller, rural communities) at increased risk of disease, especially following large rainfall events. Climate-change-related seasonal precipitation changes are projected to increase the rate of gastrointestinal illness in the region, without appropriate adaptive measures. 16

Seasonal Distribution

The seasonal distribution of water availability will most likely change. Between 1920 and 1995, input into Lake Michigan and Huron has shifted to autumn and winter due to increasing over-lake precipitation in the autumn and increasing runoff during the winter, resulting in less runoff and lake-level rise in the spring. 17 In Lake Superior, however, decreased runoff has been observed during the autumn and summer, and no change in runoff has been seen in winter and spring, suggesting seasonality in Lake Superior lake levels has decreased. 18 Warmer temperatures are expected to affect winter precipitation in the future. More winter rain could mean earlier peak flows, more runoff in autumn and winter, and less runoff in the spring. 19 20 21 22 23 Stream flow could be highly variable in the early- and mid-century (2010-2069) but increase by late-century (2070-2099). This would include an increase in winter and spring flows, and more variability and flashiness in summer flows, reflecting more extreme precipitation events. 24 

Land Use and Water Supply

Land use affects the long-term water budget of the region as well as the response of runoff to individual precipitation events. Natural landscapes more effectively buffer moisture, making it available to plants for longer and delaying the eventual runoff of water that does not undergo evapotranspiration. Grassland experiences less evapotranspiration than other land cover types, while forests allow the greatest amount of water to percolate into the surface soil. Especially in southern sections of the Great Lakes region, land cover has evolved from natural forests and grasslands to agricultural, suburban, and urban development. Impervious surfaces, such as asphalt and concrete, inhibit water percolation through the surface and direct precipitation into localized, high-volume flows. Cultivated agricultural land has high evapotranspiration, but also high surface runoff, and these conditions will amplify extreme streamflows during intense precipitation for agricultural and built environments. 25

References

  1. IJC. 2010: Groundwater in the Great Lakes Basin. International Joint Commission, Washington, DC, Ottawa, ON, and Windsor, ON.
  2. Pan, Z., and S. C. Pryor, 2009: Overview: Hydrologic regimes. In Understanding Climate Change: Regional Climate Variability, Predictability, and Change in Midwestern USA, S. Pryor, ed., Indiana University Press, 88-99.
  3. Wuebbles D.J. (2006) Executive Summary Updated 2005: Confronting Climate Change in the Great Lakes Region. Union of Concerned Scientists.
  4. Croley T.E.I. (2003) Great Lakes Climate Change Hydrological Impact Assessment: IJC Lake Ontario—St. Lawrence River Regulation Study. Technical Memorandum. Water Resources Management Decision Support. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI 126:84.
  5. Frelich L., Phillips-Mao L., Galatowitsch S. (2009) Regional climate change adaptation strategies for biodiversity conservation in a midcontinental region of North America. BIOLOGICAL CONSERVATION 142:2012.
  6. Hayhoe K., Weubbles D.J. (2008) Climate Change and Chicago: Projections and Potential Impacts. Report for the City of Chicago.
  7. Hayhoe K. (2007) Past and future changes in climate and hydrological indicators in the U.S. Northeast.
  8. Climate Dynamics 28:381–407.   Karl T.R., Melilo J.M., Peterson T.C. (2009) Global Climate Change Impacts in the United States. USGCRP.
  9. Wuebbles D.J. (2006) Executive Summary Updated 2005: Confronting Climate Change in the Great Lakes Region. Union of Concerned Scientists.
  10. Wuebbles D.J. (2006) Executive Summary Updated 2005: Confronting Climate Change in the Great Lakes Region. Union of Concerned Scientists.
  11. Hayhoe K. (2007) Past and future changes in climate and hydrological indicators in the U.S. Northeast. Climate Dynamics 28:381–407.
  12. Karl T.R., Melilo J.M., Peterson T.C. (2009) Global Climate Change Impacts in the United States. USGCRP.
  13. Frederick K., Schwarz G. (2000) Socioeconomic Impacts of Climate Variability and Change on US Water Resources. USGCRP Discussion Paper 00-21:87.
  14. Frelich L., Phillips-Mao L., Galatowitsch S. (2009) Regional climate change adaptation strategies for biodiversity conservation in a midcontinental region of North America. BIOLOGICAL CONSERVATION 142:2012.
  15. Croley T.E.I. (2003) Great Lakes Climate Change Hydrological Impact Assessment: IJC Lake Ontario—St. Lawrence River Regulation Study. Technical Memorandum. Water Resources Management Decision Support. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI 126:84.
  16. Uejio, C. K., Christenson, M., Moran, C., & Gorelick, M. (2017). Drinking-water treatment, climate change, and childhood gastrointestinal illness projections for northern Wisconsin (USA) communities drinking untreated groundwater. Hydrogeology Journal, 25(4), 969-979.
  17. Argyilan E., Forman S.L. (2003) Lake level response to seasonal climatic variability in the Lake Michigan–Huron system from 1920 to 1995. Journal of Great Lakes Research 29:488–500.
  18. Lenters J.D. (2004) Trends in the Lake Superior Water Budget Since 1948: A Weakening Seasonal Cycle. Journal of Great Lakes Research 30:20.
  19. Argyilan E., Forman S.L. (2003) Lake level response to seasonal climatic variability in the Lake Michigan–Huron system from 1920 to 1995. Journal of Great Lakes Research 29:488–500.
  20. Cherkauer K.A., Sinha T. (2010) Hydrologic impacts of projected future climate change in the Lake Michigan region. Journal of Great Lakes Research 36:33-50. DOI: 10.1016/j.jglr.2009.11.012.
  21. Mortsch L.D. (2000) Climate Change Impacts on the Hydrology of the Great Lakes -St. Lawrence System Canadian Water Resources Journal 25:121-179. DOI: 10.4296/cwrj2502153.
  22. Shmagin and Johnston, 2008   Croley T.E.I. (2003) Great Lakes Climate Change Hydrological Impact Assessment: IJC Lake Ontario—St. Lawrence River Regulation Study. Technical Memorandum. Water Resources Management Decision Support. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI 126:84.
  23. Allen, J.D., Hung, V. (2000). Water Ecology FOCUS: Climate Change and River Flows, in Sousounis, P.J., Bisanz, J.M. [Eds], Preparing for a changing climate– The potential consequences of climate variability and change, Great Lakes overview. USGCRP, pp. 51-54.
  24. Cherkauer K.A., Sinha T. (2010) Hydrologic impacts of projected future climate change in the Lake Michigan region. Journal of Great Lakes Research 36:33-50. DOI: 10.1016/j.jglr.2009.11.012.
  25. Lofgren, B. and A. Gronewold, 2012: Water Resources. In: U.S. National Climate Assessment Midwest Technical Input Report. J. Winkler, J. Andresen, J. Hatfield, D. Bidwell, and D. Brown, coordinators.