Infiltration and Unsaturated Flow under the Influence of Surface Microtopography - Model Simulations and Experimental Observations

Surface microtopography affects infiltration and soil-water flow (both magnitude and direction). The objective of this study is to evaluate the final distribution of wetting front under the influence of surface microtopography. Laboratory-scale infiltration and unsaturated flow experiments were conducted for various microtopographic surfaces and boundary conditions. In addition, two- and three-dimensional numerical modeling was conducted using the HYDRUS software. The simulated wetting front distributions were compared. The results from this combined experimental and modeling study indicated that surface microtopography had strong influences on soil water movement. A uniformly distributed wetting front was eventually achieved although soil surfaces had dissimilar topographic characteristics. However, the timing to reach the uniform flat wetting front varied, depending on surface microtopography, soil hydraulic properties, and boundary conditions.