Evaluation of Different Representations of the Particle-size Distribution to Predict Soil Water Retention. (3313)
Authors:
A. Nemes* - USDA-ARS HRSL, Beltsville, MD W.J. Rawls - USDA-ARS HRSL, Beltsville, MD Y.A. Pachepsky - USDA-ARS AWPL, Beltsville, MD
Abstract:
Detailed particle-size distribution (PSD) data or parameters derived from it are used in almost all pedotransfer functions (PTFs) to estimate soil hydraulic properties.
Most commonly, PSD is represented by the sand, silt and clay content of a soil.
However, a number of standards exist and are in use internationally to describe PSD and particle-size classes. Additionally, some authors use derived particle-size information, such as the geometric mean diameter and its standard deviation
(GMD) as input. We compared the usefulness of some of the most common representations of the PSD in estimating water retention using Group Method of Data Handling and data of three databases. We simulated the cutoff limit between silt and sand content being at 0.02 mm, 0.05 mm and at 0.063 mm – as used in many countries and also used the GMD as predictor. We could not point out one particular representation of the PSD that would clearly provide better results in estimating water retention. Using GMD to represent the entire PSD curve with two parameters did not result in significantly different estimates of water retention, than models that use distinct particle-size classes as input. We found no evidence
suggesting that using interpolated data would reduce the accuracy of the estimation of water retention.
Speaker Information: Attila Nemes, USDA-ARS HRSL, Beltsville, MD, USDA-ARS Hydrology and Remote Sensing Lab.10300 Baltimore Ave., Bldg 007, BARC-West, Beltsville, MD 20705-2350; Phone: (301) 504 5707; E-mail:
Session Information: Wednesday, November 3, 2004, 4:00 PM-6:00 PM Presentation Start: 4:00 PM (Poster Board Number: 2806)
Keywords: soil water retention; pedotransfer function; particle-size distribution; Group Method of Data Handling
