1. Experimental observation of increased apparent dispersion and mixing in a beach aquifer due to wave forcing
- Author
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Ian L. Turner, Gabriel C. Rau, and Martin S. Andersen
- Subjects
Head oscillations ,Biogeochemical cycle ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,0208 environmental biotechnology ,Aquifer ,Soil science ,02 engineering and technology ,01 natural sciences ,Physics::Geophysics ,020801 environmental engineering ,Physics::Fluid Dynamics ,Transient flow ,Flume ,Infiltration (hydrology) ,TRACER ,Order of magnitude ,Geology ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
Solute dispersion and mixing in beach aquifers is strongly influenced by highly transient flow induced from wave forcing. While transport at the groundwater-ocean interface has been modelled, little is known about the quantitative effect of wave forcing on solute dispersion and mixing in beach aquifers. We use a prototype-scale laboratory flume experiment to conduct tracer transport experiments at two locations within a wave-forced beach aquifer. For the first time we demonstrate by systematic laboratory experimentation that transient conditions in the re-circulation zone due to run-up and beach face infiltration as well as head oscillations caused by wave forcing strongly disperse and mix subsurface solute plumes. Wave forcing can increase the apparent dispersion by an order of magnitude depending on conditions, compared to solute transport without waves. Our findings illustrate that beach aquifer transport models need to consider the additional dispersion to correctly quantify mixing and biogeochemical processes in this highly dynamic zone.
- Published
- 2018