The Investigation of Infiltration Experimental Methods for Accessing to Perfect Model in Surface Irrigation

The aim of this research is to find out the applicable model for surface irrigation. In the surface irrigation method, the soil was contacted and saturated by water, therefore in this research in order to determine water permeability in soil, double ring method that is field survey, was used. Five methods includes: kostiakov, Philip, Green-Ampt, Horton and SCS, were selected and all methods were accessed by writing computer programming then their results were compared with the achieved results of double-ring experiments. It is noticeable that soil science reports of different 315 points were used. Estimated cumulative infiltration parameter, estimated infiltration rate and mean infiltration rate were calculated by using of experimental parameters like time, cumulative infiltration and infiltration rate and also by using above physical models and then the efficiency of every model were determined. Results showed that Kostiakov model had highest efficiency and it was introduced as the best model for estimating cumulative infiltration, infiltration rate and estimated mean infiltration rate. SCS and Philip models were known as the best model after Kostiakov model and the efficiency of Kostiakov, SCS (Soil Conservation service), and Philip was respectively reported 0.968, 0.881, 0.877, for 315 points. SCS method is not suitable for the area by low permeability.