Determining Coefficients of Some Water Infiltration Models in Two Calcareous Soils of Bajgah Region in Fars Province

Water infiltration into soil plays key role in water cycle and its importance forced researchers to introduce appropriate models for its quantitative study. In the present study, the Kostiakov-Lewis, Kostiakov, Philip, Horton, and SCS models were evaluated for estimating measured cumulative infiltration by double rings in two different calcareous soils of Bajgah region in Fars province. Coefficients of the aforementioned models were determined by the least sum of squared error method. Mean of error (ME), root mean error (RME), Willmot,s index of agreement (W), efficiency factor (EF) of model, index of mean error percentage (MEP) and determination coefficient (R2) were used for evaluation of the models efficiency. The Kostiakov-Lewis with R2 of 0.998 -0.999 was the most suitable model in estimation of the cumulative infiltration in the studied soils. The Kostiakov-Lewis and SCS with mean errors of 0.0019 to 0.064 overestimated, while Philip, Kostiakov and Hortonwith mean errors of -0.0033 to -0.0377 underestimated the infiltration. In general, results indicated that using the models (specifically Kostiakov-Lewis) in the studied coarse textured soil in comparison to fine textured soils for short times after beginning of infiltration had more accurate results. This matter should be considered in infiltration modeling in calcareous soils. Of course, it is recommended that the experiments be done in wider ranges of soil textures and conditions and by taking into consideration the circumstances of each soil, appropriate managerial decisions be taken.