Evaluation of one-point method in estimating infiltration characteristics (scaling method)

Infiltration in the soil is one of the determining parameters in irrigation, which affects all factors related to irrigation evaluation. On the other hand, spatial and temporal variability of infiltration parameters are a major physical limitation in managing and achieving high application efficiency of surface irrigation. The objective of the present study is to evaluate scaling method in estimating the infiltration equation parameters in furrow irrigation based on Elliott-Walker, Shepard et al., Ebrahimian et al., infilt, Valiants and Milapali methods, and also to evaluation the accuracy of the middle point and end point for the scale process. For this purpose, a reference infiltration curve is considered and then using the time of to reach the middle and end of the furrow, the scale factor of that furrow is obtained. In this research, the measured data for six furrows with soil texture and different input data were considered. According to the results, if the furrow end point is used to calculate the scaling factor in the Scaling method, the accuracy of this method will be significantly increased .Based on the evaluation, Ebrahimian's method had the best results. In the infilt method, there is no noticeable difference between using the middle point and the end point. In many cases, using the middle point in order to obtain the parameters of the penetration equation overestimates the advance value. The simplicity of the one-point scaling method is one of the advantages of this method in comparison with other methods of obtaining penetration parameters