|Sadeghzadeh, Kourosh - UNIV. OF MARYLAND|
|Shirmohammadi, Adel - UNIV. OF MARYLAND|
|Montas, Hubert - UNIV. OF MARYLAND|
Submitted to: ASAE Annual International Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 28, 2003
Publication Date: July 28, 2003
Citation: Sadeghzadeh, K., Shirmohammadi, A., Montas, H., Sadeghi, A.M. 2003. Applicability of Philip's three-parameter type infiltration equation in layered soils. Proceedings of the ASAE Meetings. Paper No. 033107. Technical Abstract: Infiltration equations are widely used in infiltration simulation through porous media in hydrology, agriculture, watershed management and design of irrigation and drainage networks. Particularly in surface irrigation systems, accurate determination of infiltration equations' parameters has a determinant role in the design of furrow, average infiltration rate, deep percolation, and runoff and distribution pattern efficiency. The most important infiltration equations which have been widely used in surface irrigation systems design and operation are Kostiakov equation, SCS method, Green & Ampt model, and Philip's two-parameter type equation. Particularly the last two equations have been used in several soil and water simulation software packages such as; DRAINMOD, DRAINMOD-N, DRINMOD-S and SWAT. In some cases unrealistic (negative) values may be achieved for A (related to Ks) and Ks in the Philip's two-parameter type equation and Ks in the Green-Ampt model. We used Kutilek's approach (used three terms instead of two terms) in Philip's infiltration equation in order to simulate infiltration process in layered soils. Before using the double rings infiltrameter and in order to track the soil moisture content variations, the TDR probes installed at different soil depths. Having gathered the field infiltration data, we applied nonlinear (for Philip's three-type infiltration equation) and linear (for Green & Ampt equation) regression analysis to find the values of A and Ks. Although Kutilek's approach can estimate the real values of Ks and A for some layered soils, it was also shown that in some cases, where C1 or C3 (Green & Ampt equation's parameters) has negative values, it cannot determine the saturated hydraulic conductivity using experimentally obtained infiltration data.