Analyses of soil water content variations and GPR attribute distributions

Water flux was investigated in the frame of the project 'preferential flow paths-3D water and solute dynamic in heterogeneous media'. The objective of the study was the non-destructive three-dimensional monitoring and description of heterogeneous flux fields with hydrological and geophysical methods. A large tank filled with homogeneous sand was set up to realize infiltration experiments. We compared the parameter distribution calculated from measurements of a ground penetrating radar system (GPR) with a simulated water content distribution using a two-dimensional numerical model based on the Van Genuchten-Mualem approach in order to assess the effectiveness of the geophysical measure for the characterization of soil water content variations. A statistical examination of both simulated water contents based on independent measured soil properties and reflection amplitudes from radargrams indicated a better conformity between geophysical data and simulated water contents assuming a heterogeneous hydraulic parameter distribution. The heterogeneous nature of the sand body could be confirmed by dye tracer experiments. The analyzed GPR attribute, the distribution of the maximum reflection amplitudes, may serve in future studies as an indicator for the expected water content heterogeneity in sandy soils. (C) 2002 Published by Elsevier Science B.V.

[1]  Harry M. Jol,et al.  The role of ground penetrating radar and geostatistics in reservoir description , 1997 .

[2]  B. Hasholt.  Bernward Hölting: HYDROGEOLOGIE: Einführung in die Allgemeine und Angewandte Hydrogeologie. Stuttgart 1980, X, 340 s., ill., 20 cm, DM26,80. Ferd. Enke Verlag. , 1981 .

[3]  G. E. Archie.  The electrical resistivity log as an aid in determining some reservoir characteristics , 1942 .

[4]  S. A. Hagrey,et al.  Preferential flow: first results of a full-scale flow model , 1999 .

[5]  Rosemary Knight,et al.  GEOSTATISTICAL ANALYSIS OF GROUND-PENETRATING RADAR DATA : A MEANS OF DESCRIBING SPATIAL VARIATION IN THE SUBSURFACE , 1998 .

[6]  Quincy Chen,et al.  Seismic attribute technology for reservoir forecasting and monitoring , 1997 .

[7]  M. Toksöz,et al.  Velocity variations and water content estimated from multi-offset, ground-penetrating radar , 1996 .

[8]  Hannes Flühler,et al.  SUSCEPTIBILITY OF SOILS TO PREFERENTIAL FLOW OF WATER : A FIELD STUDY , 1994 .

[9]  R. Schulin,et al.  Calibration of time domain reflectometry for water content measurement using a composite dielectric approach , 1990 .

[10]  Matthew Charlton,et al.  Small-scale soil-moisture variability estimated using ground penetrating radar , 2000, International Conference on Ground Penetrating Radar.

[11]  J. Robertsson,et al.  Finite‐difference modeling of electromagnetic wave propagation in dispersive and attenuating media , 1998 .

[12]  Immo Trinks,et al.  Monitoring water flow in the unsaturated zone using georadar , 2001 .

[13]  Harry M. Jol,et al.  A comparison of the correlation structure in GPR images of deltaic and barrier‐spit depositional environments , 2000 .

[14]  Feike J. Leij,et al.  The RETC code for quantifying the hydraulic functions of unsaturated soils , 1992 .

[15]  H. Perroud,et al.  Interpretation of reflection attributes in a 3-D GPR survey at Vallee d'Ossau, western Pyrenees, France , 2000 .

[16]  R. Stolt.  MIGRATION BY FOURIER TRANSFORM , 1978 .

[17]  W. M. Schuh,et al.  Spatial variation of root-zone and shallow vadose-zone drainage on a loamy glacial till in a sub-humid climate , 1993 .

[18]  A. Peter Annan,et al.  Ground‐penetrating radar monitoring of a controlled DNAPL release: 200 MHz radar , 1994 .

[19]  A. P. Annan,et al.  Electromagnetic determination of soil water content: Measurements in coaxial transmission lines , 1980 .

[20]  Gary W. Parkin,et al.  Measurement of soil water content below a wastewater trench using ground‐penetrating radar , 2000 .

[21]  Hannes Flühler,et al.  Transport of Chloride Through an Unsaturated Field Soil , 1991 .

[22]  Gary R. Olhoeft,et al.  Observed Migration of a Controlled DNAPL Release by Geophysical Methods , 1995 .

[23]  Jeffrey W. Roberts,et al.  Estimation of permeable pathways and water content using tomographic radar data , 1997 .

[24]  Pascale Senechal,et al.  Geometrical and physical parameter comparison between GPR data and other geophysical data , 2000, International Conference on Ground Penetrating Radar.

[25]  J. Feyen,et al.  Spatial analysis of saturated hydraulic conductivity in a soil with macropores , 1997 .