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Heterogeneity Affects Intertidal Flow Topology in Coastal Beach Aquifers
Author(s) -
Geng Xiaolong,
Michael Holly A.,
Boufadel Michel C.,
Molz Fred J.,
Gerges Firas,
Lee Kenneth
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl089612
Subject(s) - intertidal zone , aquifer , biogeochemical cycle , geology , saltwater intrusion , groundwater , groundwater flow , mixing (physics) , hydrology (agriculture) , environmental science , oceanography , soil science , ecology , geotechnical engineering , physics , quantum mechanics , biology
Intertidal aquifers are hotspots of biogeochemical cycling where nutrients and contaminants are processed prior to discharge to the ocean. The nature of the dynamic subsurface mixing zone is a critical control on mitigating reactions. Simulation of density‐dependent, variably saturated flow and salt transport incorporating realistic representations of aquifer heterogeneity was conducted within a Monte Carlo framework to investigate influence of nonuniform permeability on intertidal groundwater flow and salt transport dynamics. Results show that heterogeneity coupled with tides creates transient preferential flow paths within the intertidal zone, evolving multiple circulation cells and fingering‐type salinity distributions. Due to heterogeneity, strain‐dominated (intense mixing) and vorticity‐dominated (low mixing) flow regions coexist at small spatial scales, and their spatial extent reaches peaks at high tide and low tide. Such topological characteristics reveal complex tempo‐spatial mixing patterns for intertidal flow with localized areas of high and low mixing intensities, which have implications for intertidal biogeochemical processing.