Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Seasonal oscillations in water exchange between aquifers and the coastal ocean


Ground water of both terrestrial and marine origin flows into coastal surface waters as submarine groundwater discharge, and constitutes an important source of nutrients, contaminants and trace elements to the coastal ocean1,2,3,4,5. Large saline discharges have been observed by direct measurements3,6,7,8,9,10 and inferred from geochemical tracers11,12,13, but sufficient seawater inflow has not been observed to balance this outflow. Geochemical tracers also suggest a time lag between changes in submarine groundwater discharge rates12,14 and the seasonal oscillations of inland recharge that drive groundwater flow towards the coast. Here we use measurements of hydraulic gradients and offshore fluxes taken at Waquoit Bay, Massachusetts, together with a modelling study of a generalized coastal groundwater system to show that a shift in the freshwater–saltwater interface—controlled by seasonal changes in water table elevation—can explain large saline discharges that lag inland recharge cycles. We find that sea water is drawn into aquifers as the freshwater–saltwater interface moves landward during winter, and discharges back into coastal waters as the interface moves seaward in summer. Our results demonstrate the connection between the seasonal hydrologic cycle inland and the saline groundwater system in coastal aquifers, and suggest a potentially important seasonality in the chemical loading of coastal waters.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Saline groundwater circulation in a simple coastal groundwater system with a Ghyben–Herzberg interface.
Figure 2: Simulated total fresh and saline fluxes across the sea floor per metre length of shoreline.
Figure 3: Submarine groundwater discharge into Waquoit Bay, Massachusetts.


  1. Johannes, R. E. The ecological significance of the submarine discharge of groundwater. Mar. Ecol. Prog. Ser. 3, 365–373 (1980)

    ADS  Article  Google Scholar 

  2. Moore, W. S. The subterranean estuary: a reaction zone of ground water and sea water. Mar. Chem. 65, 111–125 (1999)

    CAS  Article  Google Scholar 

  3. Simmons, G. M. Importance of submarine groundwater discharge (Sgwd) and seawater cycling to material flux across sediment water interfaces in marine environments. Mar. Ecol. Prog. Ser. 84, 173–184 (1992)

    ADS  CAS  Article  Google Scholar 

  4. Slomp, C. P. & Van Cappellen, P. Nutrient inputs to the coastal ocean through submarine groundwater discharge: controls and potential impact. J. Hydrol. 295, 64–86 (2004)

    ADS  CAS  Article  Google Scholar 

  5. Burnett, W. C., Bokuniewicz, H., Huettel, M., Moore, W. S. & Taniguchi, M. Groundwater and pore water inputs to the coastal zone. Biogeochemistry 66, 3–33 (2003)

    CAS  Article  Google Scholar 

  6. Kim, G., Lee, K. K., Park, K. S., Hwang, D. W. & Yang, H. S. Large submarine groundwater discharge (SGD) from a volcanic island. Geophys. Res. Lett. 30 doi:10.1029/2003GL018378 (2003)

  7. Michael, H. A., Lubetsky, J. S. & Harvey, C. F. Characterizing submarine groundwater discharge: a seepage meter study in Waquoit Bay, Massachusetts. Geophys. Res. Lett. 30 doi:10.1029/GL016000 (2003)

  8. Robinson, M., Gallagher, D. & Reay, W. Field observations of tidal and seasonal variations in ground water discharge to tidal estuarine surface water. Ground Wat. Monit. Remediat. 18, 83–92 (1998)

    Article  Google Scholar 

  9. Smith, L. & Zawadzki, W. A hydrogeologic model of submarine groundwater discharge: Florida intercomparison experiment. Biogeochemistry 66, 95–110 (2003)

    CAS  Article  Google Scholar 

  10. Taniguchi, M., Ishitobi, T. & Saeki, K. Evaluation of time-space distributions of submarine ground water discharge. Ground Wat. 43, 336–342 (2005)

    CAS  Article  Google Scholar 

  11. Crotwell, A. M. & Moore, W. S. Nutrient and radium fluxes from submarine groundwater discharge to Port Royal Sound, South Carolina. Aquat. Geochem. 9, 191–208 (2003)

    CAS  Article  Google Scholar 

  12. Moore, W. S. Large groundwater inputs to coastal waters revealed by Ra-226 enrichments. Nature 380, 612–614 (1996)

    ADS  CAS  Article  Google Scholar 

  13. Moore, W. S. & Church, T. M. Submarine groundwater discharge — Reply. Nature 382, 122–122 (1996)

    ADS  CAS  Article  Google Scholar 

  14. Kelly, R. P. & Moran, S. B. Seasonal changes in groundwater input to a well-mixed estuary estimated using radium isotopes and implications for coastal nutrient budgets. Limnol. Oceanogr. 47, 1796–1807 (2002)

    ADS  Article  Google Scholar 

  15. Moore, W. S. High fluxes of radium and barium from the mouth of the Ganges-Brahmaputra river during low river discharge suggest a large groundwater source. Earth Planet. Sci. Lett. 150, 141–150 (1997)

    ADS  CAS  Article  Google Scholar 

  16. Bear, J., Cheng, A. H.-D., Sorek, S., Ouazar, D. & Herrera, I. in Seawater Intrusion in Coastal Aquifers — Concepts, Methods and Practices (ed. Bear, J.) (Kluwer Academic, Dordrecht, 1999)

    Book  Google Scholar 

  17. Eltahir, E. A. B. & Yeh, P. A. J. F. On the asymmetric response of aquifer water level to floods and droughts in Illinois. Wat. Resour. Res. 35, 1199–1217 (1999)

    ADS  Article  Google Scholar 

  18. Changnon, S. A., Huff, F. A. & Hsu, C.-F. Relations between precipitation and shallow groundwater in Illinois. J. Clim. 1, 1239–1250 (1988)

    ADS  Article  Google Scholar 

  19. Tapley, B. D., Bettadpur, S., Ries, J. C., Thompson, P. F. & Watkins, M. M. GRACE measurements of mass variability in the Earth system. Science 305, 503–505 (2004)

    ADS  CAS  Article  Google Scholar 

  20. Payne, R. Falmouth monthly climate reports. (accessed 30 July 2004).

  21. US Geological Survey National Water Information System (NWISWeb). (accessed 30 July 2004).

  22. Cooper, H. H. A hypothesis concerning the dynamic balance of fresh water and salt water in a coastal aquifer. J. Geophys. Res. 64, 461–467 (1959)

    ADS  Article  Google Scholar 

  23. Li, L., Barry, D. A., Stagnitti, F. & Parlange, J. Y. Submarine groundwater discharge and associated chemical input to a coastal sea. Wat. Resour. Res. 35, 3253–3259 (1999)

    ADS  CAS  Article  Google Scholar 

  24. Kohout, F. Cyclic flow of salt water in the Biscayne aquifer of southeastern Florida. J. Geophys. Res. 65, 2133–2141 (1960)

    ADS  Article  Google Scholar 

  25. Valiela, I. et al. Transport of groundwater-borne nutrients from watersheds and their effects on coastal waters. Biogeochemistry 10, 177–197 (1990)

    CAS  Article  Google Scholar 

  26. Diersch, H. J. G. Interactive, graphics-based finite-element simulation system FEFLOW for modeling groundwater flow, contaminant mass, and heat transport processes. (WASY Ltd., Berlin, Germany, 2002)

  27. Lee, D. R. Device for measuring seepage flux in lakes and estuaries. Limnol. Oceanogr. 22, 140–147 (1977)

    ADS  CAS  Article  Google Scholar 

Download references


We thank the WBNERR staff and the many MIT and WHOI faculty and students, USGS personnel, and others who assisted in the field. This work was supported by a graduate research fellowship from the US National Science Foundation.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Charles F. Harvey.

Ethics declarations

Competing interests

Reprints and permissions information is available at The authors declare no competing financial interests.

Supplementary information

Supplementary Notes

This provides further numerical modelling results and additional data and analysis from the field site at Waquoit Bay, Massachusetts. The material is organized as one Supplementary Table and 12 Supplementary Figures: numerical modeling (Supplementary Table S1 and Supplementary Figures S1–S5), conceptualization (Supplementary Figure 6), field instrumentation (Supplementary Figure S8), and field site (Supplementary Figures S7 and S9–S12). (PDF 949 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Michael, H., Mulligan, A. & Harvey, C. Seasonal oscillations in water exchange between aquifers and the coastal ocean. Nature 436, 1145–1148 (2005).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing