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Considering barometric pressure in groundwater flow investigations
Author(s) -
Spane F. A.
Publication year - 2002
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2001wr000701
Subject(s) - aquifer , hydraulic head , groundwater , groundwater flow , elevation (ballistics) , geology , flow (mathematics) , pressure gradient , vadose zone , hydrology (agriculture) , environmental science , pressure head , geotechnical engineering , mechanics , mechanical engineering , oceanography , physics , geometry , mathematics , engineering
Water level elevation measurements in wells are commonly used as a basis to delineate groundwater flow patterns (i.e., flow direction and hydraulic gradient). Barometric pressure fluctuations, however, can have a discernible impact on well water levels. These barometric effects may lead to erroneous indications of hydraulic head within the aquifer. Total hydraulic head within the aquifer, not well water level elevation, is the hydrologic parameter for determining groundwater flow direction and hydraulic gradient conditions. For low‐gradient, unconfined aquifer sites exhibiting variable vadose zone characteristics (e.g., thickness, pneumatic diffusivity), barometric pressure fluctuations can cause temporal changes in lateral flow direction and flow velocity. Discrete water level measurements used to determine the average or long‐term groundwater flow conditions, therefore, may provide nonrepresentative results. Calculation of the barometric response characteristics for individual wells provides the basis to account for the temporal effects of barometric pressure fluctuations from monitor well measurements, so that average, long‐term groundwater flow pattern behavior can be determined.