Boundary-Layer Meteorology

, Volume 29, Issue 1, pp 1–20 | Cite as

A two-layer model of soil hydrology

  • L. Mahrt
  • H. Pan
Article

Abstract

A two-layer model of soil hydrology is developed for applications where only limited computer time and complexity are allowed. Volumetric soil water is computed in a thin upper layer for use in calculation of surface evaporation. Storage of water is computed for an underlying deeper layer.

In an effort to identify the influence of significant asymmetric truncation errors in the two-layer model, this model is compared with the 100-level model of Boersma et al. (1983). Comparisons are made for modelled soils with clay, loam and sand properties for various time dependencies of potential evaporation and precipitation. Truncation errors in the resulting two-layer model appear to be modest, at least compared to errors associated with difficulty in estimation of the hydraulic diffusivity and its strong dependence on soil water content.

Minimization of the influence of truncation errors requires: (1) choosing the upper layer to be sufficiently thin, (2) allowing the soil water gradient to control surface evaporation directly and (3) using suitable numerical implementation of the evaluation of internal soil water flux.

Résumé

On propose un modèle d'hydrologie du sol à deux couches, spécialement élaboré pour des applications où le temps de calcul et la complexité doivent être aussi réduits que possible. Le contenu en eau du sol dans la mince couche de surface est utilisé pour évaluer l'évaporation, tandis que la réserve en eau est calculée pour la couche profonde, beaucoup plus épaisse.

Afin d'estimer les erreurs de troncature et leurs effets dans le modèle à deux couches, des comparaisons sont faites avec le modèle à 100 niveaux de Boersma et al. (1983). Ces comparaisons portent sur des sols de natures variées (argile, terres végétales et sable) et incluent divers taux d'évaporation potentielle et de précipitation. Les effets des erreurs de troncature dans le modèle à 2 couches semblent peu importants par rapport à ceux associés à la mauvaise connaissance de la diffusivité hydraulique et de sa dépendance à l'égard du contenu en eau du sol.

La réduction de l'influence de ces erreurs de troncature nécessite: (1) le choix d'une couche supérieure suffisamment fine; (2) le contrôle direct de l'évaporation vers l'atmosphère à partir de la répartition verticale du contenu en eau du sol; (3) l'utilisation d'une procédure particulière pour évaluer le flux d'eau entre les deux couches du sol.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Bailey, W. G. and Davies, J. A.: 1981, ‘The Effect of Uncertainty in Aerodynamic Resistance on Evaporation Estimates from the Combination Model’, Boundary-Layer Meteorol. 20, 187–199.Google Scholar
  2. Barton, I. J.: 1979, ‘A Parameterization of the Evaporation from Non-saturated Surfaces’, J. Appl. Meteorol. 18, 43–47.Google Scholar
  3. Black, T. A., Tanner, C. B., and Gardner, W. R.: 1970, ‘Evapotranspiration from a Snap Bean Crop’, Agron. J. 62, 66–69.Google Scholar
  4. Boersma, L., Ungs, M. J., and McCoy, E. L.: 1983, Transfer Problems in Soils, Ag. Exp. St., Oregon State University, Corvallis, 97331, U.S.A.; see also: W. F. Ames (ed.), Proceedings IMACS World Congress on Systems Simulation and Scientific Computation. 8–13 August, 1982. Montreal, Canada. International Association for Mathematics and Computers in Simulation.Google Scholar
  5. Budyko, M. I.: 1956, Teplovoi Balans Zemnoi Poverkhnosti, Gidrometeoizdat, Leningrad; Heat Balance of the Earth's Surface, translated by N. A. Stepanova, U.S. Weather Bureau, Washington, D.C., 1958.Google Scholar
  6. Camillo, P., Guerney, R., and Schmugge, T. J.: 1983, ‘Soil and Atmosphere Boundary Layer Model for Evapotranspiration and Soil Moisture Studies’, Water Resources Res. 19, 371–380.Google Scholar
  7. Campbell, G. S.: 1974, ‘A Simple Method for Determining Unsaturated Conductivity from Moisture Retention Data’, Soil Science 117, 311–314.Google Scholar
  8. Clapp, R. B. and Hornberger, G. M.: 1978, ‘Empirical Equations for some Soil Hydraulic Properties’, Water Resources Res. 14, 601–604.Google Scholar
  9. Davies, J. A. and Allen, C. D.: 1973, ‘Equilibrium, Potential and Actual Evaporation from Cropped Surfaces in Southern Ontario’, J. Appl. Meteorol. 12, 649–657.Google Scholar
  10. Day, P. R. and Luthin, J. N.: 1956, ‘A Numerical Solution of the Differential Equation of Flow for a Vertical Drainage Problem’, Soil Sci. Soc. Am. Proc. 20, 443–447.Google Scholar
  11. Deardorff, J. W.: 1977, ‘A Parameterization of Ground-Surface Moisture Content for Use in Atmospheric Prediction Models’, J. Appl. Meteorol. 16, 1182–1185.Google Scholar
  12. Eagleson, P. S.: 1982, ‘Dynamic Hydro-Thermal Balances at Marcroscale’, 289–360. Proceedings of World Meteorological Organization, Presented at JSC Study Conference on Land Surface Processes in Atmospheric General Circulation Models. January 5–10, 1981.Google Scholar
  13. Feddes, R. A., Bresler, E., and Neuman, S. P.: 1974, ‘Field Test of a Modified Numerical Model for Water Uptake by Root Systems’, Water Resources Res. 10, 1199–1206.Google Scholar
  14. Gardner, W. R.: 1960, ‘Dynamic Aspects of Water Availability to Plants’, Soil Sci. 89, 63–73.Google Scholar
  15. Gardner, W. R., Hillel, D., and Benyamini, Y.: 1970, ‘Post-Irrigation Movement of Soil Water, 2. Simultaneous Redistribution and Evaporation’, Water Resources Res. 6(4), 1148–1153.Google Scholar
  16. Hanks, R. J. and Bowers, S. A.: 1962, ‘Numerical Solution of the Moisture flow Equation for Infiltration into Layered Soils’, Soil Sci. Soc. Am. Proc. 26, 530–534.Google Scholar
  17. Hanks, R. J., Klute, A., and Bresler, E.: 1969, ‘A Numeric Method for Estimating Infiltration Redistribution, Drainage, and Evaporation of Water from Soil’, Water Resources Res. 5, 1064–1069.Google Scholar
  18. Hillel, D.: 1980, Fundamentals of Soil Physics, Academic Press, 413 pp.Google Scholar
  19. Jackson, R. D.: 1973, ‘Diurnal Changes in Soil Water Content during Drying’, Field Soil Water Regime 33, 37–55.Google Scholar
  20. Jersey, Gilbert R.: 1982, ‘Incorporation of a Simple Evapotranspiration Parameterization in an Efficient Model of the Atmospheric Boundary Layer’, Masters thesis, Dept. of Meteorology, The Pennsylvania State University. University Park, PA.Google Scholar
  21. Marsh, P., Rouse, W. R., and Woo, M.-K.: 1981, ‘Evaporation at a high Arctic Site’, J. Appl. Meteorol. 20, 713–716.Google Scholar
  22. Marshall, T. J. and Holmes, J. W.: 1979, Soil Physics, Cambridge University Press, Cambridge, 345 pp.Google Scholar
  23. McCumber, M. C. and Pielke, R. A.: 1981,‘Simulation at the Effects of Surface Fluxes of Heat and Moisture in a Mesoscale Numerical Model’, J. Geophys. Res. 86, 9929–9938.Google Scholar
  24. Mukammal, E. I. and Neumann, H. H.: 1977, ‘Application of the Priestly-Taylor Evaporation Model to Assess the Influence of Soil Moisture on the Evaporation from a large Weighing Lysimeter and Class A Pan’, Boundary-Layer Meteorol. 12, 243–256.Google Scholar
  25. Nimah, M. N. and Hanks, R. J.: 1973, ‘Model for Estimating Soil Water, Plant, and Atmospheric Interrelations: I. Description and Sensitivity’, Soil Sci. Soc. Amer. Proc. 37, 522–527.Google Scholar
  26. Passioura, J. B. and Cowan, I. R.: 1968, ‘On Solving the Non-linear Diffusion Equation for the Radial Flow of Water to Roots’, Agric. Meteorol. 5, 129–134.Google Scholar
  27. Rouse, W. R., Mills, P. F., and Stewart, R. B.: 1977, ‘Evaporation in High Latitudes’, Water Resources Res. 13(6), 909–914.Google Scholar
  28. Seaton, K. A., Landsberg, J. J., and Segley, R. H.: 1977, ‘Transpiration and Leaf Water Potentials of Wheat in Relation to Changing Soil Water Potential’, Aust. J. Agric. Res. 28, 355–367.Google Scholar
  29. Thornthwaite, C. W. and Mather, J. R.: 1955, ‘The Water Balance’, Publications in Climatology 8, 1, Laboratory of Climatology, Centerton, NJ, 86 pp.Google Scholar
  30. Williams, R. J., Boersma, K., and van Ryswyk, A. L.: 1978, ‘Equilibrium and actual Evapotranspiration from a Very Dry Vegetated Surface’, J. Appl. Meteorol. 17, 1827–1832.Google Scholar

Copyright information

© D. Reidel Publishing Company 1984

Authors and Affiliations

  • L. Mahrt
    • 1
  • H. Pan
    • 1
  1. 1.Department of Atmospheric SciencesOregon State UniversityCorvallisUSA

Personalised recommendations