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Abstract

Time series of water levels in piezometer nests along a forest-marsh transect near North Inlet, SC, show fluctuations that are attributable to recharge by precipitation and tidal flooding and to removal by evapotranspiration (ET) and seepage out of the soil. Volumes of water associated with these water level changes were estimated by correlating rain-induced water level increases with measured rainfalls. In the forest the ratio of water table rise to rainfall is about 10. This ratio increases with decreasing elevation to about 40 in the mid marsh where the antecedent soil moisture is generally higher. Aquatic SciencesThe relative influence of removal by ET and seepage and recharge by rain and tides varies systematically along the transect. In the mainland forest, loss of water by ET is somewhat less than infiltration, leading to a net recharge of fresh water which eventually discharges in the adjacent mid marsh. With decreasing elevation, the relative importance of recharge by rain decreases as recharge by tidal flooding increases. In the low marsh, however, these mechanisms of loss and recharge can not be discerned in the water level time series because the water table rarely, if ever, drops below the marsh surface.

Large CO2 release and tidal flushing in salt marsh crab burrows reduce the potential for blue carbon sequestration

“…Both values were characterized by large spatial variability (Supporting Information Table S2). The average value of K (75 cm d −1 , i.e., 8.76 × 10 −6 m s −1 ) fell well in the range of previous investigations (10 −7 to 6 × 10 −5 m s −1 ) in North Inlet salt marshes (Gardner and Reeves 2002). If we used the average K at a depth of 0-30 cm in the model, the carbon export rate by porewater exchange could increase by 21% at P1 and five-fold at P2, respectively.…”

Storm‐driven groundwater flow in a salt marsh

“…[6] More than three decades of research has indicated that groundwater flow in salt marsh sediments is dominated by tidal forcing, evapotranspiration (ET) and precipitation, and, in some cases, discharge of fresh groundwater from adjacent forested uplands [Gardner, 1973;Hemond and Fifield, 1982;Dacey and Howes, 1984;Harvey et al, 1987;Nuttle, 1988;Gardner and Reeves, 2002]. Note that uplands in barrier islands are normally sandy, so that rainfall typically infiltrates rather than running off undeveloped uplands.…”

“…This exchange is limited by permeability where fine-grained sediments dominate, or by the 12 h tidal period where higher-permeability sediments are present [Harvey et al, 1987]. Fresh groundwater discharging from adjacent uplands has been observed in confined aquifers below salt marshes [Tobias et al, 2001 ;Gardner and Reeves, 2002 ;Carter et al, 2008], but inundation by saline creek water at high tide typically maintains saline conditions in the surficial marsh muds. Flow within the marsh mud, then, depends on the balance between hydraulic head in the underlying confined aquifer, recharge at the marsh surface, and ET.…”

“…Coastal groundwater flow exerts key controls on coastal water supply; affects the discharge of nutrients, metals, and carbon to the coastal ocean via submarine groundwater discharge (SGD) [Moore, 2010]; and strongly influences the ecology of coastal wetlands through controls on salinity [Morris, 1995;Gardner and Reeves, 2002]. Large storms dramatically alter hydraulic forcing in coastal settings, causing extensive alterations in groundwater flow and transport, but few studies have investigated the impact of small to moderate storms on coastal groundwater flow.…”

Assessing the accuracy of monitoring wells in tidal wetlands

“…[2] Groundwater flow has been shown to play a role in the distribution and productivity of salt marsh plants [Thibodeau et al, 1998;Gardner and Reeves, 2002] and in the exchange of nutrients and radium isotopes between pore and tidal waters [Gardner, 1975;Yelverton and Hackney, 1986;Nuttle and Hemond, 1988;Krest et al, 2000]. Thus, there is increased interest in the hydrology of wetlands.…”