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

Subject Areas : Article frome a thesis

A. Neshat ¹ , M. Farhad ²

1 - استادیار دانشگاه آزاد اسلامی کرمان
2 - کارشناس ارشد آبیاری و زهکشی دانشگاه آزاد اسلامی کرمان

Received: 2013-09-16 Accepted : 2013-09-16 Published : 2013-03-21

Keywords: Hydraulic conductivity of unsaturated soil, Soil physical properties, Neural network, RETC software,

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.

References:

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.