Generally soil preferential flow occurs through soil macropores. These flows can transport a large amount of water and any type of pollutant to groundwater in a short time. This issue causes the water and soil pollution and in terms of environmental and health, affect the lives of animal and human. In this study the movement of water in preferential routes in the soil was investigated using a physical model. Also this movement was evaluated using Kinematic–Dispersive Wave (KDW) model which is a second degree non-linear partial differential equation and optimization of its coefficients. At first, the model coefficients were obtained using Particle Swarm Optimization (PSO) method. After that, the model was validated using experimental observation of rainfall hydrograph which was passed through the preferential routes of physical model and was recorded from the bottom of soil column. The results showed that the numerical model has very good agreement with experimental observations, and this prediction is better in lower rainfall intensity. Since dispersive mechanism was applied in this model and the effect of dispersive is disappeared graduatly with increase of input rainfall intensity, this effect in lower velocities causes the model to predict much better the observation. Consequently, this model can be a way to predict the preferential water flow and contaminant in soil to be eligible to make a reasonable decision in environmental management planning.