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A Flux Detection Probe to Quantify Dynamic Groundwater‐Surface Water Exchange in the Hyporheic Zone
Author(s) -
Thomle Jonathan,
Strickland Chris,
Johnson Tim C.,
Zhu Yue,
Stegen James
Publication year - 2020
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/gwat.13001
Subject(s) - hydraulic conductivity , porosity , hyporheic zone , groundwater , soil science , flux (metallurgy) , tracer , permeability (electromagnetism) , pore water pressure , flow velocity , hydrology (agriculture) , surface water , geology , water flow , environmental science , soil water , flow (mathematics) , materials science , geotechnical engineering , mechanics , chemistry , membrane , biochemistry , physics , environmental engineering , nuclear physics , metallurgy
A new probe was designed to quantify groundwater‐surface water exchange in the hyporheic zone under dynamic stage condition. Current methods focus on either vertical pore water velocity or Darcy flux measurements. Both parameters must be understood to evaluate residence time and mass flux of constituents. Furthermore, most instruments are not well suited for monitoring instantaneous velocity or flux under dynamic exchange conditions. For this reason, the flux detection probe (FDP) was designed that employs electrogeophysical measurements to estimate in situ sediment porosity, which can be used to convert pore water velocity to Darcy flux. Dynamic pore water velocity is obtained by monitoring fluid conductivity and temperature along the FDP probe. Pressure sensors deployed at the top and bottom of the probe provide the additional information necessary to estimate vertical permeability. This study focuses on the use of a geophysical method to estimate pore water velocity, porosity, and permeability within a controlled soil column where simulated river water displaces simulated groundwater. The difference between probe derived and theoretical pore water velocity using natural tracers such as electrical conductivity and temperature was −4.9 and 3.9% for downward flow and 1.1 and 12.8% for upward flow, respectively. The difference in porosity calculated from mass and volume packed in the soil column and probe measure porosity ranged between −3.2% and 1.5%. Also, the calculated hydraulic conductivity differed from probe derived values by −8.9%.