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The Feasibility of Recharge Rate Determinations Using the Steady‐State Centrifuge Method
Author(s) -
Nimmo John R.,
Stonestrom David A.,
Akstin Katherine C.
Publication year - 1994
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1994.03615995005800010007x
Subject(s) - groundwater recharge , centrifuge , hydraulic conductivity , hydrology (agriculture) , san joaquin , geology , soil science , volumetric flow rate , vadose zone , soil water , geotechnical engineering , mechanics , aquifer , groundwater , physics , nuclear physics
The establishment of steady unsaturated flow in a centrifuge permits accurate measurement of small values of hydraulic conductivity ( K ). This method can provide a recharge determination if it is applied to an unsaturated core sample from a depth at which gravity alone drives the flow. A K value determined at the in situ water content indicates the long‐term average recharge rate at a point. Tests of this approach have been made at two sites. Unsaturated K values were measured easily for sandy core samples from a site in the San Joaquin Valley of California. The results indicate that a better knowledge of the matric pressure profiles is required before a recharge rate can be determined. Fine‐textured cores from a site in southeastern Washington required new developments of apparatus and procedures, especially for making centrifuge measurements with minimal compaction of the samples. Measured K values led to preliminary recharge rate determinations that are reasonable considering the known hydrology and topography of the site.