Interacting vegetative and thermal contributions to water movement in desert soil

Vadose Zone Journal
By: , and 

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Abstract

Thermally driven water-vapor flow can be an important component of total water movement in bare soil and in deep unsaturated zones, but this process is often neglected when considering the effects of soil–plant–atmosphere interactions on shallow water movement. The objectives of this study were to evaluate the coupled and separate effects of vegetative and thermal-gradient contributions to soil water movement in desert environments. The evaluation was done by comparing a series of simulations with and without vegetation and thermal forcing during a 4.7-yr period (May 2001–December 2005). For vegetated soil, evapotranspiration alone reduced root-zone (upper 1 m) moisture to a minimum value (25 mm) each year under both isothermal and nonisothermal conditions. Variations in the leaf area index altered the minimum storage values by up to 10 mm. For unvegetated isothermal and nonisothermal simulations, root-zone water storage nearly doubled during the simulation period and created a persistent driving force for downward liquid fluxes below the root zone (total net flux ~1 mm). Total soil water movement during the study period was dominated by thermally driven vapor fluxes. Thermally driven vapor flow and condensation supplemented moisture supplies to plant roots during the driest times of each year. The results show how nonisothermal flow is coupled with plant water uptake, potentially influencing ecohydrologic relations in desert environments.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Interacting vegetative and thermal contributions to water movement in desert soil
Series title Vadose Zone Journal
DOI 10.2136/vzj2010.0023
Volume 10
Issue 2
Year Published 2011
Language English
Publisher Soil Science Society of America
Contributing office(s) Nevada Water Science Center
Description 13 p.
First page 552
Last page 564