Determining the hydraulic properties of a swelling soil from a transient evaporation experiment

Most methods used to determine the hydraulic properties of swelling soils (i.e., the shrinkage curve [e(v)], the moisture retention curve [h(v)], and the hydraulic conductivity curve [K(v)]) are time consuming because they require measurements of several different parameters (either in separate experiments or by using very expensive equipment). We propose a simple evaporation experiment to simultaneously determine all three soil hydraulic properties. The method is illustrated using samples of a Vertisol from the Senegal River valley. The value of e(v) is determined during the experiment by horizontal and vertical linear deformation measurements, whereas an inverse parameter estimation method is used to determine h(vT) and K(v). This method relies on a water flow model that takes into account the three-dimensional and anisotropic deformation of the soil. The reliability of the estimated parameter values was checked and we compared the results with those obtained by a multistep outflow experiment. Good agreement was found between the results of the different procedures. The sensitivity of the method to deformation was also analyzed. In the soil investigated, the inverse method does not seem to require the use of a water flow model that takes into account deformation. However, a correction for deformation is needed if the characteristic functions are sought in terms of the volumetric water content of the soil.

[1]  Philippe C. Baveye,et al.  Numerical model of 3-dimensional anisotropic deformation and 1-dimensional water flow in swelling soils , 1997 .

[2]  Van Genuchten,et al.  A closed-form equation for predicting the hydraulic conductivity of unsaturated soils , 1980 .

[3]  Ole Wendroth,et al.  Unsaturated hydraulic conductivity from transient multistep outflow and soil water pressure data , 1994 .

[4]  J. Feyen,et al.  ON THE CHARACTERIZATION OF PROPERTIES OF AN UNRIPE MARINE CLAY SOIL II. A METHOD ON THE DETERMINATION OF HYDRAULIC PROPERTIES , 1992 .

[5]  David H. Bailey,et al.  Multiprecision Translation and Execution of Fortran Programs , 1993 .

[6]  J. Feyen,et al.  ON THE CHARACTERIZATION OF PROPERTIES OF AN UNRIPE MARINE CLAY SOIL: I. SHRINKAGE PROCESSES OF AN UNRIPE MARINE CLAY SOIL IN RELATION TO PHYSICAL RIPENING , 1992 .

[7]  John R. Nimmo,et al.  Modeling of soil water retention from saturation to oven dryness , 1994 .

[8]  J. Feyen,et al.  Prediction of dynamic hydraulic properties in a ripening soil , 1993 .

[9]  Jack C. Parker,et al.  Determining Soil Hydraulic Properties from One-step Outflow Experiments by Parameter Estimation: I. Theory and Numerical Studies1 , 1985 .

[10]  J. Bronswijk.  Shrinkage Geometry of a Heavy Clay Soil at Various Stresses , 1990 .

[11]  D. Chen,et al.  A New Simplex Procedure For Function Minimization , 1986 .

[12]  Jan W. Hopmans,et al.  Optimization of Hydraulic Functions from Transient Outflow and Soil Water Pressure Data , 1993 .

[13]  W. Yeh.  Review of Parameter Identification Procedures in Groundwater Hydrology: The Inverse Problem , 1986 .

[14]  T. Talsma.  Moisture Profiles in Swelling Soils , 1974 .

[15]  A. Klute,et al.  The Calibration of the Richards Flow Equation for a Draining Column by Parameter Identification1 , 1981 .

[16]  P. Baveye.  Operational Aspects of the Mechanics of Deforming Porous Media: Theory and Application to Expansive Soils , 1992 .

[17]  A. Klute,et al.  Transport in Soils: The Balance of Momentum1 , 1968 .

[18]  Randel Haverkamp,et al.  Parameter constraints on closed-form soilwater relationships , 1992 .

[19]  Jack C. Parker,et al.  Determining Soil Hydraulic Properties from One‐step Outflow Experiments by Parameter Estimation: II. Experimental Studies , 1985 .