Modeling for Estimating Soil Moisture Dimensions in Drip Irrigation in Layer Soil Using Dimensional Analysis Method

In order to obtain the latera arrangements and distance between emitters in Drip irrigation, the soil moisture distribution should be considered. The variety in pore sizes and permeability of each layer beside the changes in influential forces (mostly matrix and gravity), cause the wetted pattern in layered soils to be different from homogeneous soil. The present research studies wetted zone in layered soils. In addition, some scientific-experimental equations with the help of dimensional analysis and the Buckingham π theorem were suggested to estimate the size of the wetted perimeter. There were six sets of experiments including different sequences of three soil textures (light, moderate and heavy) and under discharge 4 liters per hour for drip irrigation. The experiments were conducted in a physical model with transparent walls. At the end of irrigation, the lowest depth of advance was related to S2 (light to moderate to heavy). The highest wetted diameter was related to the S2 soil treatment (with the least depth of advance). The lowest wetted soil diameter at the end of irrigation was related to S6 treatment (moderate to heavy on light), which had almost more depth in this treatment than other treatments. The reason is the low difference between medium and heavy textures. That is, the delay time of the moisture front to cross the common boundary of the two layers was less. The information obtained in this study can be used to design and manage drip irrigation systems.