An Assessment of Infiltration Models in the Surface Soil of Geological Formations in Aleshtar Watershed, the Province of Lorestan

Soil infiltration is one of the key processes in the design of irrigation systems, water resources management, soil conservation, and erosion control in watershed management. As to the importance of the mentioned subject, infiltration changes and modeling were investigated on the surface soil of geological formations in this study. The double-ring infiltrometer was used to measure the infiltration rate in the surface soil of some geological formations on the Alashtar Watershed due to the flooding potential of the area. The performance of the modified Green-Ampt, Philip, Kostiakov, the US Soil Conservation Service (SCS), and the Horton models were evaluated in estimating the infiltration rate in the surface soils formed or deposited on those formations. The results indicated that the Asmari Formation (Oml) had a higher cumulative infiltration, average infiltration rate, terminal infiltration rate than other formations. This was followed by the Quaternary Formations (Q and Qt). The results indicated that the modified Green-Ampt model had an acceptable accuracy as compared to other models in estimating infiltration in the Pabdeh (EL), the Khami Group (Jk, Mz), the Gachsaran (M), the Aghajari (Muplaj, Mpaj), and the Bakhtyari (Plb) Formations with efficiency coefficients of 93.9, 94.4, 95.9, 97.6, 87.7, and 92.7%, respectively. The Kostiakov model was more suitable for the Q and Oml Formations, and the Horton model was the best for the Qt Formation (C.C= 0.925), which may be used to quantify the amount of infiltrated water and to estimate the runoff volume for the soils formed or deposited on those formations different on the mentioned geological formations.