Investigation of Semi-Empirical Model of Unsaturated Hydraulic Conductivity Based on Some Measurable Physical Soil Properties, Case Study: Baghin Plain, Kerman

Document Type : Research Paper

Authors

• A. Neshat
• M. Farhad

Abstract

Unsaturated hydraulic conductivity is one of the basic properties of soil that governs the water movement in the field. As application of any of the various available methods in the field deemed impracticable due to its difficulty of implication and high costs, we resorted to a laboratory method and modeling to develop a method, which may be easily used in determining this important parameter. Saturated hydraulic conductivity was determined by the falling head method. Hydrometry method was used for grain size distribution; pH, EC, and contents of mineral carbonate and gypsum were also determined using the approved methods. Unsaturated hydraulic conductivity (Ku) was estimated using the discharge equation in a unit area, the Darcy's law, neural network, and the RETC, SPSS, Curve Expert, and Excel software. It was observed that the Power subroutine of the SPSS, with the maximum coefficient of determination and the highest correlation coefficient, and the minimum RMSE presents the best model.

Keywords

• Hydraulic conductivity of unsaturated soil
• Soil physical properties
• Neural network
• RETC software

20.1001.1.20086377.1392.6.16.6.2

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References

1. Harvey, D.J. and Yeh, J., 1990, Effective

   Unsaturated Hydraulic Conductivity of

   Layered Sands, Water Resources

   Research, Vol 26, No6, 1271-1279.

   2. Setiawan, B.T. and Nakano, M., 1993, On

   the determination of unsaturated hydraulic

   conductivity from soil moisture profiles

   and water retention curves, Soil Science,

   156, 386-395.

   3. Saxton, K.E. and Rawls, W.J. and

   Romberger, J.S. and Papendick, R.I.,

   1986, Estimating generalized soil- water

   characteristics from texture, Soil Science

   Society American Journal, 50, 1031-1036.

   4. Van Genuchten, M.T., 1980, Aclosed

   form equation for predicting the hydraulic

   conductivity of unsaturated Soil Science

   Society American Journal, 44, 892-898.

   5. Wagner, B. and Tarnawski, V.R. and

   Hennings, V. and Muller, U. and

   Wessolek, G. and Plagge, R. 2001,

   Evaluation of pedotransfer functions for

   unsaturateal soil hydraulic conductivity

   using an independent data set, Geoderma,

   102, 275-297.

   6. Wosten, J.H.M. and Pachepsky, Ya.A.

   and Rawls, W.J., 2001, Pedotransfer

   functions: bridging the gap between

   available basic soil data and missing soil

   hydraulic characteristics, Journal of

   Hydrology, 251, 123-150.

   7. Zhang, R. and Van Genuchten, M.T.,

   1994, New models for unsaturated soil

   hydraulic properties, Soil Science, 163,

   425-435.

   8. Zhuang, J. and Nakayama, K. and Yu,

   G.R. and Miyazaki, T., 2001, Predicting

   unsaturated hydraulic conductivity of soil

   based on some basic soil properties, Soil

   & Tillage Research, 59, 143-154.