Analytical framework for the characterization of the space-time variability of soil moisture Academic Article uri icon


  • Hydrologic processes that are components of regional water balance occur on scales considerably smaller than the region itself. Evapotranspiration and percolation during interstorm periods are hydrologic processes whose rates depend on conditions that vary significantly in space due to soil and vegetation heterogeneity as well as moisture redistribution under topography. Infiltration and runoff during storm periods also vary significantly in space due to the spatial variability in surface moisture conditions. In time, these hydrologic processes are switching between climate-limited and soil-controlled regimes during both storm and interstorm periods. The space and time dependence inherent in these components of water balance limit the applicability of lumped or averaged models. These simplified models appear in hydrologic applications whose objectives are to estimate regional water balance. They are also present in the hydrologic parametrization of atmospheric models. In this paper an analytical model of soil-water balance that is distributed in space and time is developed. In order to retain analytical tractability, it is assumed that the space-time variability is statistically homogeneous and isotropic. The surface hydrology is forced with a stochastic model of rainfall that phenomenologically captures the arrival of intense precipitating cells within clusters that are imbedded in squall lines and rainbands. An analysis of the spatial and temporal fluctuations in both the rainfields and soil moisture fields are made in frequency-domain. The effects of averaging operations on these fields are delineated and the consequences for hydrologic and atmospheric models that use lumped water balance expressions are quantified. 1994.

published proceedings

  • Advances in Water Resources

author list (cited authors)

  • Entekhabi, D., & Rodriguez-Iturbe, I.

citation count

  • 100

complete list of authors

  • Entekhabi, Dara||Rodriguez-Iturbe, Ignacio

publication date

  • January 1994