Numerical and Empirical Simulation of Wetting Pattern in Subsurface Drip Irrigation in Clay Loam Soil

Document Type : Research Paper


1 Msc student, Department of Water and Soil, Faculty of Agriculture, Shahrood University of Technology, Shahrood, Iran

2 Department of Water and Soil, Faculty of Agriculture, Shahrood University of Technology, Shahrood, Iran

3 Department of Water and Soil, Shahrood University of Technology, Shahrood, Iran

4 Department of Water and Soil, Faculty of Agriculture, Shahrood University of technology, Shahrood, Iran.

5 ِDepartment of Water and Soil, Faculty of Agriculture, Shahrood University of Technolog, Shahrood, Iran.


Subsurface drip irrigation has been widely applied in arid area as a water-saving irrigation technology. But, a comprehensive knowledge of wetting pattern in drip Irrigation is essential for designing and managing such system. Simulation models have been proved to be useful method for this purpose. Therefore, this research was carried out to investigate the dimensions of wetting pattern in subsurface drip irrigation in a clay loam soil using invers modeling method with Hydrus 2D and based on experimental results and empirical models. The results were categorized into four sections: 1. Laboratory results showed that only for emitters with 8 liters per hour and installed at 15 cm depth, the wetted dimension below the emitter is more than the one above the emitter. 2. Sensitivity analysis on soil hydraulic parameters showed that the most sensitive parameter is θs, but the soil porosity continuity (l) and the remaining moisture content (θr) are not effective parameters. 3. Wetting front in emitters with discharge rate more than 2 liters per hour and installed at 15 cm depth in the clay loam soil is reached to the soil surface, while it does not reach to the soil surface in the emitters installed at 30 cm depth, even with discharge rate up to 8 liters per hour. Therefore, the evaporation rate from the soil surface is minimized. 4. Statistical indices showed that there is no significant differences among the empirical, numerical and the observation data, so that the normalized RMSE for the numerical and empirical models varied from 4.4 to 6.2 and 3.4 to 8 percent, respectively. Consequently, the results of this study showed that the proposed empirical model and Hydrus model can be used for estimation of wetting pattern in the soil.


Main Subjects

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