%0 Journal Article
%T Laboratory Experiments on the Effect of Microtopography on Soil-Water Movement: Spatial Variability in Wetting Front Movement
%A Leif Sande
%A Xuefeng Chu
%J Applied and Environmental Soil Science
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/679210
%X The effect of microtopography on soil-water movement is a topic of interest for a range of disciplines, with experimental studies investigating the relationship between the two lacking. Laboratory experiments were conducted by simulating rainfall across packed soil surfaces to investigate the effect of microtopography on wetting front movement within experimental soil profiles. In small soil box experiments, the observed wetting fronts for soil profiles showed considerably deeper movement beneath a smooth surface than depressions for 12¨C60£¿min rainfalls. For large soil box experiments, the wetting front reached moisture sensors installed at 5 and 10£¿cm depths and corresponding to various rough and smooth surface features at significantly different times, with movement being most rapid beneath the smooth surface. Wetting front movement was ¡°quicker¡± beneath surface peaks than depressions for the rough surface as attributed to 2D/3D unsaturated flow. This study provides valuable experimentally based insight into the effect of microtopography on soil-water movement. 1. Introduction Infiltration is controlled by a number of factors such as soil capillary suction, initial moisture content, hydraulic conductivity, and pore structure. For practical applications (such as unsaturated flow modeling), infiltration is generally considered homogeneous across a soil surface. In reality, infiltration rates often vary significantly and dynamically across a soil surface [1, 2]. Infiltration characteristics also strongly influence subsequent water percolation through the vadose zone. The factors that control spatial and temporal variations in infiltration and soil-water percolation can be divided into three categories: site characteristics, soil characteristics, meteorological characteristics [3]. Site characteristics include slope, microtopography, vegetative cover, grazing conditions, and subsurface conditions; soil characteristics include saturated and unsaturated hydraulic conductivity, degree of aggregation, bulk density, and the presence of macropores; and meteorological characteristics include rainfall intensity, duration, and spatial variations [3]. Soil moisture condition is an important site characteristic, which exerts a significant influence on water movement in soils [3¨C6]. Microtopography is a site characteristic that can affect spatial variations in infiltration and soil-water percolation directly and indirectly and is a research area in need of significantly more work [7]. Generally, increasing soil roughness will result in increased infiltration [8¨C10]
%U http://www.hindawi.com/journals/aess/2012/679210/