Campus Units

Agronomy

Document Type

Article

Publication Version

Published Version

Publication Date

4-2008

Journal or Book Title

Water Resources Research

Volume

44

Issue

4

DOI

10.1029/2008WR006961

Abstract

Most measurement approaches for determining evaporation assume that the latent heat flux originates from the soil surface. Here, a new method is described for determining in situ soil water evaporation dynamics from fine-scale measurements of soil temperature and thermal properties with heat pulse sensors. A sensible heat balance is computed using soil heat flux density at two depths and change in sensible heat storage in between; the sensible heat balance residual is attributed to latent heat from evaporation of soil water. Comparisons between near-surface soil heat flux density and Bowen ratio energy balance measurements suggest that evaporation originates below the soil surface several days after rainfall. The sensible heat balance accounts for this evaporation dynamic in millimeter-scale depth increments within the soil. Comparisons of sensible heat balance daily evaporation estimates to Bowen ratio and mass balance estimates indicate strong agreement (r2 = 0.96, root-mean-square error = 0.20 mm). Potential applications of this technique include location of the depth and magnitude of subsurface evaporation fluxes and estimation of stage 2–3 daily evaporation without requirements for large fetch. These applications represent new contributions to vadose zone hydrology.

Comments

This article is published as Heitman, J. L., Xinhua Xiao, Robert Horton, and T. J. Sauer. "Sensible heat measurements indicating depth and magnitude of subsurface soil water evaporation." Water resources research 44, no. 4 (2008). doi: 10.1029/2008WR006961. Posted with permission.

Rights

Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.

Language

en

File Format

application/pdf

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