Modified Retention Functions for Arid Vadose Zone Studies
M.J. Fayer, B.J. Andraski, and E.A. Jacobson
Abstract
Much of the western United States has an arid climate that makes it
suitable for waste disposal. The objective of this study was to
highlight the availability of new water retention functions that can be
used in vadose zone simulation studies at arid sites. These functions,
described by Rossi and Nimmo (1994) and Fayer and Simmons (1995), can
represent water retention under both dry and wet conditions with just a
few parameters. The functions were incorporated into an existing 1-D
finite difference model that included liquid water flow, water vapor
diffusion, plant transpiration, and heat flow. Simulations are presented
to illustrate the use of these functions at three field sites: 1) an
unvegetated site in the Amargosa Desert in Nevada, 2) a site vegetated
with Bromus tectorum (cheatgrass) in Washington, and 3) a gravel-covered
lysimeter in Washington. Results showed that the use of the new
retention functions improved the predictions of near-surface matric
potential at site 1, water contents at site 2, and water content and
drainage at site 3.
This abstract was published in the proceedings from the 1998 Soil
Science Society of America Conference, p. 187.