Application and Comparison of Particle – Size Distribution Models to Estimate Soil Hydraulic Properties

Masoudi, R. (2009) Application and Comparison of Particle – Size Distribution Models to Estimate Soil Hydraulic Properties. Masters thesis, University of Zabol.

Application and Comparison of.pdf

Download (92kB) | Preview


Water retention curve and hydraulic conductivity are of the main soil hydraulic functions. Determination of these functions is important in many processes such as irrigation and drainage calculations, determining soil moisture deficit and modeling water flow in soil. The water retention curve describes the relationship between soil volumetric water content and the matric potential. The Hydraulic conductivity function describes the relationship between the unsaturated Hydraulic conductivity and soil volumetric water content. Since direct measurements of both functions in laboratory and field conditions are relatively costly and time-consuming considered indirect methods for measuring these functions. One method is to use particle-size distribution and soil bulk density such as Aria and Paris model. Since measured data of particle size distribution is limited, mathematical models can be fitted on available data. The fitted models can be used as input data to Aria and Paris model for estimating soil hydraulic functions. In this research seven parametric models including Jacky, Fredlund, van Genuchten, Gompertz, SL, ONL, ORL and nonparametric model of spline are used to model the particle size distribution curve. The data used were the measured particle size distribution for 24 different soils existing in UNSODA (Unsaturated Soil Database). The models compassion is performed through three criteria, AIC, RMSE and r2. The results showed that nonparametric model of spline, had better performance for estimation than other models. Also in parametric models Jacky model with one parameter had better performance for estimation. On the other hand the linear relationship between the Particle Size Distribution and the Void Size Distribution presented by Aria and Paris is not true in all soil textures. In this research it was true in sand and silt loam soils. As a result the modification of this relation for different soil texture is suggested. It is resulted that the parameter numbers is not the only effective factors to estimate soil hydraulic properties by Aria and Paris model. Besides the best fitted model to the particle size distribution is not necessarily the best model to estimate soil hydraulic properties. Soil texture and nature of model affect also the estimation quality by models.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Particle Size Distribution, Soil Water Characteristic Curve, Unsaturated Hydraulic Conductivity, Aria and Paris Model
Subjects: S Agriculture > S Agriculture (General)
T Technology > TC Hydraulic engineering. Ocean engineering
Depositing User: admin admin1 admin2
Date Deposited: 18 Apr 2016 06:59
Last Modified: 18 Apr 2016 06:59

Actions (login required)

View Item View Item