Preferential Flow Revealed by Hydrologic Modeling Based on Predicted Hydraulic Properties
Frédéric Gérarda,*,
Mark Tinsleya,c and
K. Ulrich Mayerb
a INRA, Centre de Nancy, Unité Biogéochimie des Ecosystèmes Forestiers, Forêt d'Amance, 54280 Champenoux, France
b Univ. of British Colombia, Dep. of Earth and Ocean Sciences, 6339 Stores Road, V6T 1Z4 Vancouver, BC, Canada
c Present address: Chemistry School, Clark Hall, West Virginia Univ., Morgantown, WV 26506
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Fig. 1. Comparison of on-site control measurements of the soil water content at different soil depths. Error bars correspond to the standard deviation. White bars: mean value measured with the trase-system Soil Moisure time domain reflectometry (TDR) probes; light-gray colored bars: mean value measured with the Theta Probe Delta-T Devices; dark-gray colored bars: gravimetric measurements.
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Fig. 2. Variations in precipitation (P, dark solid line), throughfall (Th, square symbols), and potential evapotranspiration (PET, light solid line).
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Fig. 3. Result of the simulations made with predicted hydraulic parameters and using the two types of prediction for hydraulic conductivity: Ks with L = 0.5 (cross), and K0 with L  0.5 (circles). Mean and spread of the soil moisture content as measured by means of six time domain reflectometry probe replicates are shown (thick line: mean; thin lines: mean ± sd).
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Fig. 4. Simulated water content at 60 cm by taking into account the prediction uncertainties given by ROSETTA (light curves) and using Ks and L = 0.5. Cross: simulation with the mean values of hydraulic parameters. Mean and spread of the measured soil moisture content are shown (thick line: mean; thin lines: mean ± sd).
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Fig. 5. Simulated water content at 60 cm using Ks and L = 0.5 and by setting the water table during the wet periods (i.e., winter and fall) at the 2-m depth (open squares) and at the 3-m depth (filled squares). For comparison purposes, results calculated by neglecting the influence of the water table are given (cross). Mean and spread of the measured soil moisture content are shown (thick line: mean; thin lines: mean ± sd).
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Fig. 6. Simulated water content at 60 cm using Ks and L = 0.5 and by setting the water table at the 3-m depth, without readjusting the soil-dependent transpiration parameters (filled squares), after readjustment (open diamonds). For comparison purpose, results calculated by neglecting the influence of the water table are given (cross). Mean and spread of the measured soil moisture content are shown (thick line: mean; thin lines: mean ± sd).
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Fig. 7. Simulated water content with preferential flow (circles), after calibration of the parameters involving in Eq. [11]. For comparison purposes, results calculated without preferential flow and using Ks and L = 0.5 are shown (cross). Mean and spread of the measured soil moisture content are shown (thick line: mean; thin lines: mean ± sd).
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Fig. 8. Influence of the position of the water table on the results of simulations performed with preferential flow at the 15-cm depth (Gray circles: water table set at the 3-m depth in winter and fall, and at the 100-m depth in summer and spring). For comparison purposes, results calculated by setting no influence of the water table are shown (open circles).
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Copyright © 2004 by the Soil Science Society of America.
