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This article in SSSAJ

  1. Vol. 56 No. 4, p. 1042-1050
    Received: Oct 30, 1990

    * Corresponding author(s):
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Inverse Method for Determining Soil Hydraulic Functions from One-Step Outflow Experiments

  1. J. C. van Dam ,
  2. J. N. M. Stricker and
  3. P. Droogers
  1. Contribution from the Dep. of Hydrology, Soil Physics, and Hydraulics, Agricultural Univ., Nieuwe Kanaal 11, 6709 PA, Wageningen, the Netherlands



Optimization of the parameters describing the soil hydraulic functions θ(h) and K(h), in which θ is the volumetric water content, h is the soil water pressure head, and K is the unsaturated hydraulic conductivity, in a transient-flow experiment is a promising method to derive soil hydraulic information. Laboratory outflow experiments are a typical example. However, estimates from one-step outflow experiments, using only cumulative outflow data in the objective function, are often unreliable and non-unique. Using the MVG model for θ(h) and K(h), the sensitivity of parameters to outflow data is shown to depend on their actual values. The one-step outflow method was applied on samples of four soils of different texture. Additionally, the soil hydraulic functions of these soils were measured by alternative, direct methods. From the validation, it appeared that cumulative outflow data have to be supplemented with θ(h) data to get reliable estimations.

This study was financed by the EC (contract EV4C-0054-NL) as part of the research project Spatial Variability of Land Surface Processes.

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