See more from this Session: Measurement and Modeling of near-Surface Soil Water and Energy Fluxes: I
Wednesday, October 19, 2011: 11:10 AM
Henry Gonzalez Convention Center, Room 007B, River Level
An understanding of soil water dynamics is essential for sound management of land resources. Water movement in Vertisols is poorly understood because of the drastic changes in soil hydraulic properties with changes in soil water content. When dry, Vertisols contain cracks that facilitate rapid transport of water into the subsoil. Because of the tortuous and irregular nature of the cracks, information on how the spatial and temporal extent of cracks affects dynamics of water flow is difficult to obtain. Recently, electrical resistivity tomography (ERT) has emerged as a tool for measuring soil water content and shows promise as a method for imaging cracking along with water content in Vertisols. Cracks produce sharp discontinuities in electrical resistivity in the surrounding soil and can be detected by ERT. For this study, three-dimensional ERT surveys were collected in drying and wetting cylces of a Vertisol. To facilitate imaging water dynamics, relationships were developed between soil moisture and electrical resistivity, including the effects of cracks. Water contents measured by neutron thermalization were used to validate ERT estimates of soil water dynamics.