Paper Information

Journal:   JOURNAL OF AGRICULTURAL SCIENCES   MARCH 2008 , Volume 13 , Number 1 (SUPPLEMENT); Page(s) 103 To 114.
 
Paper: 

COMPARISON OF SOME METHODS FOR ESTIMATION OF UNSATURATED SOIL HYDRAULIC CONDUCTIVITY

 
 
Author(s):  FOOLADMAND H.R., KAVEH F., ZAND PARSA SH., BOUSTANI F., MOAFPOURIAN GH.R.
 
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Abstract: 

In this research, Gardner method was used for measurement of unsaturated soil hydraulic conductivity by measuring the volume of outflowing water with respect to time in pressure plates apparatus for five pressures of 03, 1, 5, 10 and 15 bar. The predictive methods of van Genuchten, Saxton et al., and Zand-Parsa were used for estimating the unsaturated soil hydraulic conductivity for 20 soil samples. The soils were collected from Marvdasht and Fasa regions in Fars province, and had different textures groups. The results showed that Saxton et al.'s method was the least accurate of three above named methods in predicting unsaturated hydraulic conductivity in most soils. On the other hand, van Genuchten method had the least differences with measured data. Therefore, on the basis of limited data gathered in this experiment we can conclude that van Genuchten method is the superior method due to its simplicity and wide testing across the world. However, since the Zand-Parsa method in many soils tested by- us gave closer results to experimental values than van Genuchten method, therefore, Zand-Parsa method, which is based on specific liquid-vapour interfacial area around the soil particles, can be used as a new approach for estimation unsaturated soil hydraulic conductivity. Zand-Parsa method uses the van Genuchten equation for estimation soil moisture characteristics curve, and the thickness of water layer and the specific liquid-vapour interfacial area around soil particles could be determined at each water content.
One advantage of Zand-Parsa method is estimating unsaturated soil hydraulic conductivity function without needing a value for soil saturated hydraulic conductivity, which is in contrast to the van Genuchten and all other empincal methods of estimating soil unsaturated hydraulic conductivity.

 
Keyword(s): UNSATURATED SOIL HYDRAULIC CONDUCTIVITY, ZAND-PARSA METHOD, VAN GENUCHTEN METHOD
 
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