HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Chan, T. P. Articles by Govindaraju, R. S. Search for Related Content PubMed Articles by Chan, T. P. Articles by Govindaraju, R. S. GeoRef GeoRef Citation Agricola Articles by Chan, T. P. Articles by Govindaraju, R. S. Related Collections Soil Hydrology Vadose Zone Processes and Chemical Transport

Estimating Soil Water Retention Curve from Particle-Size Distribution Data Based on Polydisperse Sphere Systems

School of Civil Engineering, Purdue University, 500, Stadium Mall Drive, West Lafayette, IN 47907-2501

View larger version (23K): [in a new window]   Fig. 1. Schematic of the polydisperse sphere systems in two dimensions: (left) impenetrable hard spheres and (right) overlapping spheres.

View larger version (19K): [in a new window]   Fig. 2. Particle-size distributions: (a) with constant y and varying µy (thicker lines for µy = 2, thinner line for µy = 4); (b) with constant µy and varying y (thicker lines for y = 0.5, thinner line for µy = 0.8). The cumulative mass fraction (cmf) is plotted as dash–dot line. cdf, cumulative distribution function; pdf, probability density function.

View larger version (23K): [in a new window]   Fig. 3. Particle-size distribution of Beerse podzol II sand (code no. 4061) plotted on a normal probability scale (y axis). Data points falling on a straight line follow a lognormal distribution. The solid line represents the best-fit curve given by Eq. [29].

View larger version (35K): [in a new window]   Fig. 4. Measured and estimated cumulative mass fractions for all 119 sandy soils. The dashed line is a linear regression of the data points. The R2 and RMSE imply the goodness of fit of the dashed line.

View larger version (14K): [in a new window]   Fig. 5. Comparison of the proposed totally impenetrable spheres (TIS) and fully penetrable spheres (FPS) models' (a) effective pore-size distribution and (b) water retention curve.

View larger version (20K): [in a new window]   Fig. 6. The water retention curves of the totally impenetrable sphere models with varying y.

View larger version (29K): [in a new window]   Fig. 7. Estimated and measured normalized water contents for all 119 soils. The scaling factor is treated as a fitting parameter in obtaining the totally impenetrable spheres (TIS) and fully penetrable spheres (FPS) model estimates. VG, van Genuchten model.

View larger version (17K): [in a new window]   Fig. 8. Wagram sand (code no. 1142): (a) measured particle-size distribution data and the lognormal distribution fit (solid line); (b) measured water retention curve and the proposed models with fitted . Considerable change in the water content occurs in the high saturation range, perhaps indicating a secondary pore system. TIS, totally impenetrable spheres model; FPS, fully penetrable spheres model; and VG, van Genuchten model.

View larger version (40K): [in a new window]   Fig. 9. Scaling factor vs. the mean parameter µy and the standard deviation parameter y of the lognormal distribution. The dashed line indicates the theoretical value of . TIS, totally impenetrable spheres model; FPS, fully penetrable spheres model.

View larger version (54K): [in a new window]   Fig. 10. Estimated and measured normalized water contents for all 119 soils. The scaling factor is fixed at 4. A wider scatter of data points is expected as a result. TIS, totally impenetrable spheres model; FPS, fully penetrable spheres model.

View larger version (24K): [in a new window]   Fig. 11. The RMSE of the totally impenetrable spheres (TIS) model prediction on water retention data vs. the mean parameter µy of the lognormal particle-size distribution.

View larger version (23K): [in a new window]   Fig. 12. The measured and estimated soil water retention curves of Troup loamy sand (code no. 1012) (a) with fitted and (b) with theoretical . The fitted value is higher than the theoretical one. TIS, totally impenetrable spheres model; FPS, fully penetrable spheres model; and VG, van Genuchten model.

View larger version (24K): [in a new window]   Fig. 13. The measured and estimated soil water retention curves of Kootwijk sand (code no. 4520) (a) with fitted (b) with theoretical . The proposed TIS model does not match the shape of the measured retention curve very well. TIS, totally impenetrable spheres model; FPS, fully penetrable spheres model; and VG, van Genuchten model.

View larger version (23K): [in a new window]   Fig. 14. The measured and estimated soil water retention curves of Beerze podzol II sand (code no. 4061) (a) with fitted (b) with theoretical . The TIS model provides a very good fit to the data. TIS, totally impenetrable spheres model; FPS, fully penetrable spheres model; and VG, van Genuchten model.