Groundwater  Sea Water Exchange

 
 
  1. Holly Michael (now at USGS)

  1. Hanan Karam

  1. Fred Day-Lewis (USGS)

  1. Alan Garder (WHOI)

Seepage Workers

Drilling from a boat

Novel Pseudo-cylindrical intertidal seepage flux quantifiers

Forty standard seepage meters

Interpretation of discharge zones for saline circulation mechanisms along a transect perpendicular to the shoreline in Waquoit Bay  [Michael et al., Nature, 2005].


Discharge data from August 2003 and February 2004 is presented in the top panel. Color bars represent the approximate extent of each zone of discharge along the transect. Zone 1 (cross-hatching) corresponds to tidal pumping and extends from the shoreline to approximately 28 m into the bay. Zone 2 (red shading) corresponds to nearshore circulation due to tides and waves and extends approximately 3 m from the high tide mark. Dispersive circulation discharges in zone 3 (blue-green shading), along the bayward edge of the fresh discharge. Seasonal saline outflow occurs in zone 4 (purple shading). Seasonal flow has been measured between 13 and 35 m from shore, but the zone likely extends to the shoreline, depicted by the dashed purple bracket, where February measurements were not possible. Discharge measurements reveal that net saline discharge offshore over a tidal cycle (~0.026 m3/s), due only to seasonal saline exchange, is greater than the total saline outflow from other circulation mechanisms (~0.023 m3/s, which may also include some seasonal outflow).

  1. H. A. Michael, A. Mulligan and C. F. Harvey, "Seasonal Water Exchange between Aquifers and the Coastal Ocean,"  Nature,  436, 2005

  1. H. A. Michael, J. Lubetsky and C.F. Harvey, "Characterizing submarine groundwater discharge: a seepage meter study in Waquoit Bay, Massachusetts", GRL, 30(6), 2003.

Waquoit Bay