Fitting Different Models of Soil-Moisture Characteristic Curve on 30 Soil Samples in Fars Province

Document Type : Complete scientific research article

Authors

Abstract

Background and Objectives: Soil moisture characteristic curve is one of the most important soil hydraulic properties, and shows the relation between soil suction and soil moisture content. Direct measurement of this curve is costly and time-consuming. Therefore, an alternative to measurement is to estimate this curve using the more easily available soil properties. On the other hand, many models have been presented for fitting to measued data of this curve. However, their fitting ability on different kinds of soil have been rarely investigated.
Materials and Methods: In this study, 30 measured surface soil samples with high variaty texture from the depth of 0 to 30 cm in different regions of Fars province have been used. Selected soils were classified into three textures of fine, medium and coarse. Then, 10 useful soil moisture characteristic curve models (Gardner, Brooks and Corey, Campbell, van Genuchten, Tani, Boltzman, Feremi, Fredlund and Xing, Groenevelt and Grant and Dexter et al.) were fitted on the data, and the parameters of each medel in each soil sample were determined, and then the most appropriate fitted model in each soil group was determined. To determine the best model, the combination of statistical equations and linear correlation was used, and then the value of mean square deviation (MSD) was calculated to evaluate the different models for fitting soil moisture characteristic curve.
Results: The results indicated that the fitted models were better in medium texture group than the fine and coarse texture groups. The results showed that in fine texture group the models of Brooks and Corey, Campbell, van Genuchten, Fredlund and Xing, Groenevelt and Grant and Dexter et al., in medium texture group the models of Gardner, Groenevelt and Grant and Dexter et al., and in coarse texture group the models of Gardner, van Genuchten, Groenevelt and Grant and Dexter et al. were appropriate. Consequently, the results according to the MSD values indicated that the model of Dexter et al. was the most appropriate model for fitting to the measured data of soil moisture characteristic curve. Furthermore, the results of this study showed that the famous model of van Genuchten was good for futting to the measured soil moisture characteristic curve data. On the other hand, the models of Tani, Boltzman and Feremi were not appropriate.
Conclusion: The results of this study investigated that the model of Dexter et al. was better than the other models for three textural group (fine, medium and coarse) for 30 soil samples of Fars province. Also. similar results have been reported by other investigators for the soil samples in Gilan province.

Keywords


-1.Bayat, H., Ebrahimi, E., Rastgo, M., Zare Abyaneh, H.R., and Davatgar, N. 2013. Fitting
different soil water characteristic curve models on the experimental data of various textural
classes of Guilan province soils. Soil and Water Science. 23: 3. 151-167. (In Persian)
2.Brooks, R.H., and Corey, A.T. 1964. Hydraulic properties of porous media. Colorado State
University, Hydrology Paper No. 3., Fort Collins, USA.
3.Campbell, G.S. 1974. A simple method for determining unsaturated conductivity from
moisture retention data. Soil Science. 117: 311-314.
4.Dexter, A.R., Czyz, E.A., Richard, G., and Reszkowska, A. 2008. A user-friendly water
retention function that takes account of the textural and structural pore spaces in soil.
Geoderma. 143: 143-153.
5.Fooladmand, H.R., and Hadipour, S. 2012. Evaluation of parametric pedotransfer functions
for estimating soil water characteristic curve in Fars province. J. Soil Water Sci. 58: 25-37.
(In Persian)
6.Fooladmand, H.R., Torabi, R., and Amindin, E. 2009. Application of Statistics in Soil and
Water. Marvdasht Islamic Azad University. First edition., 201p. (In Persian)
7.Fredlund, D.G., and Xing, A. 1994. Equations for the soil water characteristic curve. Can.
Geotech. J. 31: 521-532.
8.Gardner, W. 1956. Mathematics of isothermal water conduction in unsaturated soils.
International Symposuim on Physico Chemical Phenomenon in Soils. Washington DC.,
Pp: 78-87.
9.Groenevelt, P.H., and Grant, C.D. 2004. A new model for the soil water retention curve that
solves the problem of residual water contens. Europ. J. Soil Sci. 55: 479-485.
10.Homapoor Ghoorabjiri, M., and Rasoulzadeh, A. 2014. Derivation of pedotransfer function
to estimate parameters of double-exponential equation for soil water retention curve. Water
and Irrigation Management. 4: 1. 45-57. (In Persian)
11.Kobayashi, K., and Salam, M.U. 2000. Comparing simulated and measured values using
mean squared deviation and its components. Agron. J. 92: 345-352.
12.McKee, C., and Bumb, A. 1984. The importance of unsaturated low parameters in designing
a hazardous waste site. Hazardous Wastes and Environmental Emergencies Hazardous
Materials Control Research Institute National Conference. March Houston, TX., Pp: 50-58.
13.McKee, C., and Bumb, A. 1987. Flow-testing coalbed methane production wells in the
presence of water and gas. SPE Formation Evaluation, Pp: 599-608.
14.Mirzaee, S., and Ghorbani Dashtaki, Sh. 2015. Investigation and comparison of the
evaluation indicators efficiency of soil water retention curve models. Iran. J. Irrig. Drain.
9: 2. 274-282. (In Persian)
15.Nabizadeh, E., and Beigi Harchegani, H. 2011. The fitting quality of several water retention
models in soil samples from Lordegan, Charmahal-va-Bakhtiari. J. Water Soil. 25: 3. 634-645.
(In Persian)
16.Tani, M. 1982. The properties of a water-table rise produced by a one dimensional, vertical,
unsaturated flow (in Japanese with an English summary). J. Japan. Soc. 64: 409-418.
17.van Genuchten, M.Th. 1980. A closed-form equation for predicting the hydraulic
conductivity of unsaturated soils. Soil Sci. Soc. Amer. J. 44: 892-898.