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This article in SSSAJ

  1. Vol. 58 No. 1, p. 49-56
     
    Received: Aug 11, 1992
    Published: Jan, 1994


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doi:10.2136/sssaj1994.03615995005800010007x

The Feasibility of Recharge Rate Determinations Using the Steady-State Centrifuge Method

  1. John R. Nimmo ,
  2. David A. Stonestrom and
  3. Katherine C. Akstin
  1. Water Resources Division, U.S. Geological Survey, MS-421, 345 Middlefield Rd., Menlo Park, CA 94025

Abstract

Abstract

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.

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