Effects of Slope, Flow Rate and Soil Texture on Expansion of the Wetting front in Homogeneous Soils from a Point Source

A cuboid-shaped physical model with the dimensions of 160 cm×120 cm×60 cm in length, height and width, respectively, was built to study the advance of the wetting front. The results indicated that, in all the experiments, the largest value for the maximum wetted radius at all slopes was observed in the soil with clay texture followed by that with sandy clay loam and the smallest in the soil with loamy sand texture. The maximum wetting front radius in the experiments varied from 37 to 115 cm. When the other conditions were kept constant, the maximum wetting front radius increased at higher emitter flow rates. When the slope was kept constant, the maximum infiltration depths at the location of the emitter axis at constant volume of irrigation water were that of the soil with loamy sand texture followed by the soil with sandy clay loam texture with the soil with clay texture having the minimum infiltration depth. The depth of the wetting front under the emitter in the experiments varied from 37 to 65 cm. In addition, at higher slopes, the depth at which the maximum wetting front radius occurred was closer to the ground surface. The minimum depth at which the largest wetting front radius occurred was 4.5 cm in the clay soil at emitter rate of 8 L/h and 20% slope and the maximum was 19 cm in the loamy sand soil at emitter flow rate of 2 L/h and 0% slope. The highest percentage of wetted soil downstream of the emitter (81%) was that of the soil with clay texture at emitter flow rate of 8 L/h and 20% slope.