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Presenters Notified: November 2012

Program Schedule Posted:November 2012

Abstracts Available: January 2013

Meeting:
17-22 February 2013

Befus, K. M., Department of Geological Sciences, The University of Texas at Austin, USA, kevinbefus@utexas.edu
Cardenas, M. B., Department of Geological Sciences, The University of Texas at Austin, USA, Cardenas@jsg.utexas.edu
Swanson, T. E., Department of Geological Sciences, The University of Texas at Austin, USA, tswanson@mail.utexas.edu
Tait, D., Centre for Coastal Biogeochemistry Research, Southern Cross University, Lismore, douglas.tait@scu.edu.au
Santos, I. R., Centre for Coastal Biogeochemistry Research, Southern Cross University, Lismore, Australia, isaac.santos@scu.edu.au
Erler, D., Centre for Coastal Biogeochemistry Research, Southern Cross University, Lismore, Australia, dirk.erler@scu.edu.au

THERMAL DYNAMICS OF INTERTIDAL SEDIMENT AFFECTED BY DIFFUSE GROUNDWATER DISCHARGE

Terrestrially-originated heat flux is a major component of the coastal energy budget and can regulate habitat quality and biogeochemical reaction rates. We investigate the subsurface thermal regime of a sandy intertidal zone affected by groundwater-seawater interactions. We installed a transect of thirteen piezometers, each containing 4 thermistors, to measure vertical and horizontal water flux and temperature time series below the sediment-water interface. Time-lapse electrical resistivity profiles provided additional insight into the foreshore subsurface hydrodynamics. Together, these observations revealed three thermal patterns in the intertidal sediment corresponding to different hydraulic settings: rapid heat penetration in the variably saturated swash zone, cool subsurface temperatures supported by groundwater, and mean lagoon temperatures set by tidally-induced porewater circulation. Measured groundwater fluxes indicated predominantly seaward flow except during high tides, supporting the significance of terrestrial groundwater gradients and the potential for tidally-driven circulation. The distal piezometers also showed upwards but highly variable vertical groundwater fluxes. One-dimensional heat transport models indicated a predominance of thermal conduction, but a multi-dimensional flow model, taking into account recharge from precipitation, would better allow for analysis of site hydrodynamics.

Poster presentation

Session #:SS46
Date: 2/21/2013
Time: 18:00 - 19:30