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Determination of recharge rates using temperature‐depth profiles in wells
Author(s) -
Boyle Joseph M.,
Saleem Z. A.
Publication year - 1979
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/wr015i006p01616
Subject(s) - groundwater recharge , aquifer , geology , groundwater , dimensionless quantity , soil science , hydrology (agriculture) , geotechnical engineering , mechanics , physics
Recharge rates to the shallow dolomite aquifer in northeastern Illinois are determined using a theory which describes the simultaneous transfer of heat and fluid in a porous medium. Temperature‐depth profiles in a nonpumping well are used to determine vertical groundwater velocities of the downward leakage of water recharging the aquifer which is overlain by semiconfining beds of clay‐rich glacial drift. Calculated and observed depths of penetration (19 m) of the annual surface temperature wave, and demonstration of the thermal stability of the well, validate application of the theory, which uses a dimensionless parameter β to relate curvature in temperature‐depth profiles to the magnitude of vertical leakage. Generally, the magnitude of β decreases as the depth interval L within the aquitard increases. The corresponding decrease in the vertical component of groundwater velocity accompanies a gradual coarsening with depth of the aquitard materials. Temperature differences over time at a given depth within a thermally stable well are found to be within the accuracy of the temperature measuring system. Analysis of variations in β Over time shows that the variability can be due to the limitations of the resolution (0.01°C) of the temperature measuring system. Recharge rates determined by analyses of temperature‐depth profiles range from 2.47×10 −9 to 9.86×10 −9 m/s and agree with estimates resulting from water‐budget method.