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Calibration of Base Flow Separation Methods with Streamflow Conductivity
Author(s) -
Stewart Mark,
Cimino Joseph,
Ross Mark
Publication year - 2007
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/j.1745-6584.2006.00263.x
Subject(s) - base flow , streamflow , surface runoff , conductivity , hydrology (agriculture) , calibration , subsurface flow , environmental science , drainage basin , hydraulic conductivity , geology , soil science , groundwater , soil water , chemistry , physics , geography , geotechnical engineering , ecology , cartography , quantum mechanics , biology
The conductivity mass‐balance (CMB) method can be used to calibrate analytical base flow separation methods. The principal CMB assumptions are base flow conductivity is equal to streamflow conductivity at lowest flows, runoff conductivity is equal to streamflow conductivity at highest flows, and base flow and runoff conductivities are assumed to be constants over the period of record. To test the CMB assumptions, fluid conductivities of ground water, surface runoff, and streamflow were measured during wet and dry conditions in a 12‐km 2 stream basin. Ground water conductivities at wells varied an average of 6% from dry to wet conditions, while stream conductivities varied 58%. Shallow ground water conductivity varied significantly with distance from the stream, with lowest conductivities of 87 μS/cm near the divide, a maximum of 520 μS/cm 59 m from the stream, and 215 μS/cm 22 m from the stream. Runoff conductivities measured in three rain events remained nearly constant, with lower conductivities of 35 μS/cm near the divide and 50 μS/cm near the stream. The CMB method was applied to the records from 10 USGS stream‐gauging stations in Texas, Kentucky, Georgia, and Florida to calibrate the USGS base flow separation technique, HYSEP, by varying the time parameter 2 N *. There is a statistically significant relationship between basin areas and calibrated values of 2 N *, expressed as N = 0.46 A 0.44 , with N in days and A in km 2 . The widely accepted relationship N = 0.83 A 0.2 is not valid for these basins. Other analytic methods can also be calibrated with the CMB method.