title: Influence of seasonal variations in sea level on the salinity regime of a coastal groundwater-fed wetland.
abstract: Seasonal variations in sea level are often neglected in studies of coastal aquifers; however, they may have important controls on processes such as submarine groundwater discharge, sea water intrusion, and groundwater discharge to coastal springs and wetlands. We investigated seasonal variations in salinity in a groundwater-fed coastal wetland (the RAMSAR listed Piccaninnie Ponds in South Australia) and found that salinity peaked during winter, coincident with seasonal sea level peaks. Closer examination of salinity variations revealed a relationship between changes in sea level and changes in salinity, indicating that sea level-driven movement of the fresh water-sea water interface influences the salinity of discharging groundwater in the wetland. Moreover, the seasonal control of sea level on wetland salinity seems to override the influence of seasonal recharge. A two-dimensional variable density model helped validate this conceptual model of coastal groundwater discharge by showing that fluctuations in groundwater salinity in a coastal aquifer can be driven by a seasonal coastal boundary condition in spite of seasonal recharge/discharge dynamics. Because seasonal variations in sea level and coastal wetlands are ubiquitous throughout the world, these findings have important implications for monitoring and management of coastal groundwater-dependent ecosystems.
authors.affiliation: School of the Environment, Flinders University, Adelaide, SA, 5001, Australia.
authors.forename: Cameron
authors.initials: C
authors.lastname: Wood
authors.forename: Glenn A
authors.initials: GA
authors.lastname: Harrington
mesh_terms: D005618:Fresh Water / Q000737:chemistry*; D060587:Groundwater / Q000737:chemistry*; D008962:Models, Theoretical; D009792:Oceans and Seas; D054712:Salinity; D012621:Seasons; D012623:Seawater / Q000032:analysis / Q000737:chemistry; D013021:South Australia; D014872:Water Movements; D053833:Wetlands