Scaling and Spatial Analysis of Infiltration in Marghmalek Watershed in Shahrekord

Infiltration is one of the most important parameters in irrigation and agriculture. Knowledge of soil infiltrability is needed for designing an efficient irrigation system. However، determination of soil infiltration variability، though it is a difficult task، is a prerequisite for any precision agriculture setup. In this study، spatial variability of infiltration at the regional scale (Shahrekord watershed) is investigated. A total of 111 infiltration curves، obtained by double ring method with constant water head، were used to scale the infiltration. Four theoretical models، namely، Green- Ampt، Kostiakov، Kostiakov-Lewis، and Philip’s were fitted to the data. Philip model was the best، based on Pearson correlation and MAE statistics. Transfer factor (A) and sorptivity (S) were spatially distributed in the watershed and were scaled by two different scaling factors of and، respectively. Afterwards، all 111 infiltration curves were scaled. Nugget effect and range of was 0. 0001 and 0. 793 km، which implies a high spatial correlation structure. Therefore، scaling by was superior to scaling by. Pearson correlation of 0. 944 and an error of 0. 426 between the measured and de-scaled data were determined.