A Simulation Analysis of Thermal Effects on Evaporation From Soil
- 1 August 1984
- journal article
- Published by American Geophysical Union (AGU) in Water Resources Research
- Vol. 20 (8) , 1087-1098
- https://doi.org/10.1029/wr020i008p01087
Abstract
The Richards equation, which expresses the conservation of water in an isothermal soil, has a more general form in a nonisothermal soil. In using the latter, it is necessary to know soil temperature, and modeling becomes considerably more complicated. A detailed, numerical simulation model quantifies the thermal effects for two hypothetical soils under two climates. During characteristic 4‐day climatic sequences, in a season of soil heating, diffusion of vapor due to thermally induced vapor concentration gradients suppresses evaporation. The suppression is greatest (5–15% in this set of experiments) under arid conditions. Under these conditions, such thermal vapor diffusion also distorts the usual diurnal pattern of evaporation. Evaporation is generally more sensitive to isothermal than to thermal vapor diffusion. Variations in time and depth of the soil temperature cause corresponding variations in the water transport coefficients. These, in turn, result in biases (2–5%) and diurnal distortions of evaporation rates. Liquid flow attributable to the dependence of matric potential on temperature accounts for about 1% of evaporation in our experiments. In simulations of 1 month duration for each combination of soil and climate, the joint neglect of all thermal effects mentioned above introduces an error of only about 1% in the average evaporation rate and does not distort its time distribution significantly.This publication has 24 references indexed in Scilit:
- Comparison of Field‐measured and Calculated Soil‐heat FluxesSoil Science Society of America Journal, 1976
- In situ Measurement of Gas Diffusion Coefficient in SoilsSoil Science Society of America Journal, 1976
- Diurnal Soil‐Water Evaporation: Comparison of Measured and Calculated Soil‐Water FluxesSoil Science Society of America Journal, 1974
- Measurement of the Transport Coefficients for Coupled Flow of Heat and Moisture in a Medium SandSoil Science Society of America Journal, 1974
- On the Interaction of Water and Heat Transport in Frozen and Unfrozen Soils: I. Basic Theory; The Vapor PhaseSoil Science Society of America Journal, 1974
- On the Interaction of Water and Heat Transport in Frozen and Unfrozen Soils: II. The Liquid PhaseSoil Science Society of America Journal, 1974
- Soil Water Evaporation, Isothermal Diffusion, and Heat and Water TransferSoil Science Society of America Journal, 1970
- Evaporation of Water From Soils As Influenced By Drying With Wind or RadiationSoil Science Society of America Journal, 1967
- Soil Moisture Transport Due to Thermal Gradients: Practical AspectsSoil Science Society of America Journal, 1966
- Water movement in porous materials: Part 2 - The separation of the components of water movementBritish Journal of Applied Physics, 1963