Application of One-Dimensional Model to Simulate Vertical Water Flow in Unsaturated Soil

In this study, one-dimensional equation of  water flow in saturated-unsaturated soil was solved using finite volume method and implicit scheme. The relationship between unsaturated moisture content and pressure load was determined using Van Genechten and Brooks-Corey hydraulic functions. The validation results of the model showed that the model accurately estimated the load pressure values. The Root Mean Square Error of the pressure load for the Van Genuchten and Brooks-Corey hydraulic functions was 0. 0181 and 0. 0439 meter, respectively. After confirmation of the results of the model, the effects of three different methods for estimating the hydraulic parameters of soil by ROSETTA software were evaluated on the soil moisture characteristics curve. In the first method the complete ROSETTA model, in the secound mehtod  only soil texture and in the third method in addition of soil texture, poros medial shape parameter (l=0. 5) were considered. Comparison of the results of the model with the Hydrus 1D model showed that the prepared model had very good accuracy in all cases. Also, the results showed that with time passage and more soil drying, due to the effect of physical properties and soil porosity, the difference between three methods increases.