Simulation of water infiltration in the soil using HYDRUS-1D software and field data

In the present study, HYDRUS 1D software was used to estimate the hydraulic parameters of the Van Genuchten- Moalem model and simulation of water infiltration in soil of four stations of Gonbad University, Artificial Lake, Kalaleh and Negin Shahr with loam soil texture by reverse method. For this purpose, three groups with a different number of hydraulic parameters selected for the optimization process were defined. In the first group, only the cumulative penetration data measured as software input was used. In the second group, the soil moisture content measured at 0.3 atmospheres (FC) and in the third group, the amount of moisture in the 15 atmospheric suction (PWP) as supplementary data for the inverse solution along with the data cumulative infiltration was used. After optimization of hydraulic parameters of soil, change of water infiltration with time simulated by HYDRUS 1D. In kalaleh station, optimized parameters øs, ø r and α value 0.34, 0.027 and 0.014 obtained. In neginshar, optimized parameters α, n and ks parameters 0.0075, 1.52 and 0.012cm/min obtained. In Artificial Lake optimized parameters α, n and ks parameters 0.011, 1.39 and 0.016 cm/min obtained. In Gonbad university station optimized parameters value ks and α value 0.011cm/min and 0.005 obtained. After optimizing the hydraulic parameters of the soil, using HYDRUS software, water infiltration simulated with time. The result showed that Hydrus software predicted the data to be slightly higher than the actual amount. The results showed that at all stations, the R2 value is high, indicating a high correlation between field data and Hydrus software. In the kalaleh station, there was a greater correlation between field infiltration data and Hydrus software with high R2 coefficient (0.997) and the predicted data by the software was approximately with field data was equal. And at Negin shahr station, the difference between field data and Hydrus software simulated data was higher. At all stations, the R2 value is high, indicating a high correlation between field data and Hydrus software. In the kalaleh station, there was a greater correlation between field infiltration data and Hydrus software and the predicted data by the software was approximately with field data was equal. At Negin shahr station, the difference between farm data and Hydrus software was higher. According to the results Hydrus software simulated cumulative infiltration well and with over time, the infiltration rate was slightly higher than field data.