Deep arid system hydrodynamics 1. Equilibrium states and response times in thick desert vadose zones

Water Resources Research
By: , and 



Quantifying moisture fluxes through deep desert soils remains difficult because of the small magnitude of the fluxes and the lack of a comprehensive model to describe flow and transport through such dry material. A particular challenge for such a model is reproducing both observed matric potential and chloride profiles. We propose a conceptual model for flow in desert vadose zones that includes isothermal and nonisothermal vapor transport and the role of desert vegetation in supporting a net upward moisture flux below the root zone. Numerical simulations incorporating this conceptual model match typical matric potential and chloride profiles. The modeling approach thereby reconciles the paradox between the recognized importance of plants, upward driving forces, and vapor flow processes in desert vadose zones and the inadequacy of the downward‐only liquid flow assumption of the conventional chloride mass balance approach. Our work shows that water transport in thick desert vadose zones at steady state is usually dominated by upward vapor flow and that long response times, of the order of 104–105 years, are required to equilibrate to existing arid surface conditions. Simulation results indicate that most thick desert vadose zones have been locked in slow drying transients that began in response to a climate shift and establishment of desert vegetation many thousands of years ago.

Publication type Article
Publication Subtype Journal Article
Title Deep arid system hydrodynamics 1. Equilibrium states and response times in thick desert vadose zones
Series title Water Resources Research
DOI 10.1029/2001WR000824
Volume 38
Issue 12
Year Published 2002
Language English
Publisher American Geophysical Union
Contributing office(s) Nevada Water Science Center, Toxic Substances Hydrology Program
Description 1308; 15 p.
First page 44-1
Last page 44-15
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