Soil matric suction and active zone depth in Oklahoma

Abstract

Soil matric suction is an important parameter in unsaturated soils. The shrink-swell properties of expansive soils is controlled by soil matric suction. Matric suction variations cause volume change in expansive soils, which further causes damages to pavements and foundations. This research makes use of field measurements of matric suction obtained from the Oklahoma Mesonet and the Department of Energy's Atmospheric Radiation Measurement network to estimate active zone depth. The long-term matric suction measurement indicated a seasonal pattern of matric suction variation. The shallower depth of soil is more sensitive to the climatic conditions. Two methodologies, empirical equation and numerical analysis, were used to calculate the active zone depth in Oklahoma. The active zone depth is approximately 0.5 to 4 m depending on the soil properties and climatic conditions. The diffusion coefficient and saturated hydraulic conductivity are the two important parameters controlling the active zone depth.