Impact of Temperatures on Evaporation from Soils under Different Hydraulic Conditions

A. Ben Neriah, S. Assouline, U. Shavit, M. I. Dragila, N. Weisbrod

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The magnitude, direction and strength of the hydrologic response for a given degree of climate warming, is a critical yet unresolved question in climatology and hydrology. Temperature not only affects potential evaporation (EP), it also affects various properties of the evaporating medium such as hydraulic conductivity, surface tension and retention forces. Actual evaporation of soil solution is a complex process in which meteorological parameters as well as soil and solution properties play a role. This complexity emphasizes the importance of evaluating future evaporation rates under potential conditions related to global warming. Here, we explore the effect ambient temperatures have on the soil solution evaporation process. A set of isothermal laboratory experiments were carried out in a Climate Controlled Laboratory (CCL) at different temperatures, comparing evaporation rates from sand filled columns with different boundary and initial conditions to a DI water filled column (from which EP was deduced). The explored temperatures were 35, 25, 15 and 5°C. It was shown that under a constant-shallow water table, soil evaporation closely follows EP; an increase in ambient temperature results in higher values of both. On the other hand, with a constant-deep water table, the evaporation coefficient (KE) had a decreasing trend with temperature, excluding the low temperature experiment (5°C). Moreover, under these conditions a noticeable decrease in KE over time was observed at both high (35°C) and low (5°C) isothermal temperatures. This is likely due to the development of a dry surface layer. In summary, our experiments, carried out under highly controlled conditions, reveal that evaporation and temperature have a complex non-linear relationship. Thus, the soil water evaporation process needs to be further explored and quantified and KE cannot always be determined from simple empirical equations.
Original languageEnglish
Title of host publicationAmerican Geophysical Union, Fall Meeting 2012
StatePublished - 1 Dec 2012
Event American Geophysical Union, (AGU) Fall Meeting 2012 - San Francisco, San Francisco, United States
Duration: 3 Dec 20127 Dec 2012

Conference

Conference American Geophysical Union, (AGU) Fall Meeting 2012
Country/TerritoryUnited States
CitySan Francisco
Period3/12/127/12/12

Keywords

  • 1818 HYDROLOGY / Evapotranspiration

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