Evaluation of Different Procedures for Determining Philip Equation Coefficients in Sequential Irrigation Process of Furrows

Document Type : Research Paper

Authors

Abstract

There are different methods for estimation of soil infiltration equations’ coefficients depending on irrigation system. In this study, seasonal variations of the Philip equation coefficients (PEC) were investigated in three different soil textures including loam, sandy loam and sandy clay loam soils. The PEC,s were calculated using four following mehods: Rawls, one-point Shepard, Clemmens and adjusted Weibo methods. The advance phase was simulatied using SURFACE software. The results showed that the Rawls and adjusted Weibo methods estimated the advance phase more accurate than the others in the three soil textures. The sorptivity coefficient (S) at the fourth irrigation was compared with the first one and it showed that S decreased to 85, 10 and 82 percent for Clemmens, one-point Shepard and adjusted Weibo methods, in loamy soil, respectively. Similarly, it decreased to 74, 54 and 65 for the sandy clay loam soil from first to fourth irrigation event. The result showed no trend for transmisivity coefficient (A). Sensitivity analysis remarked that the S was more affected by inflow discharge in one-point Shepard and adjusted Weibo methods than the two others,  and also it was affected by hydraulic conductivity in Rawls method.

Keywords

Files

Share

How to cite

Statistics