Document Type : Research Paper
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Abstract
The Guelph Permeameter technique (GP) is one of the proper methods for measuring the saturated hydraulic conductivity (Kfs) above the water table. This study was done by Guelph Permeameter model 2800k1 in 20 auger holes at Research Farm of Abourayhan Campus. Soil texture was determined for the Research Farm, using the hydrometer method. Water outlet flow of the permeameter was measured in four phases under constant ponding heads (H) of 5, 10, 15 and 20 cm, respectively. The field saturated hydraulic conductivity (Kfs) and matric flux potential (Øm), based on successful testing and Guelph analysis, were evaluated by different methods. The results indicated that, in heavy soils, increasing submergence depth of H2 relative to H1, is an appropriate solution for reducing the Guelph's two-head analysis failure in soil hydraulic conductivity estimation. In this study, well shape factor (C) was also calculated by five different methods. Later, the effect of the calculated C factor by various methods was studied in Guelph's two-head analysis. The results showed that using unsaturated effect in the calculations lowers the possibility of obtaining negative values of Kfs and Øm in Xiang Solution. Also, there was a very high correlation between Guelph successful two-head analysis when Xiang and Numeral Solutions were used for calculating C factor (r=0.98).
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