MACROPORE VELOCITY MAPPING OF ALLUVIAL SOIL USING TEMPORAL ELECTRICAL RESISTIVITY IMAGING

Riparian soils are uniquely susceptible to the formation of macropores, voids with preferential flow in comparison to surrounding strata, which are hypothesized to promote fast transport of water through soil layers. Temporal Electrical Resistivity Imaging (TERI) can locate spatial heterogeneities in soil wetting patterns caused by preferential flow through macropores, thus optimizing the design of riparian buffers. In a field evaluation of naturally occurring macropores, the TERI technique would detect the wetted zone around a macropore similar to an area of increased hydraulic conductivity in a heterogeneous soil matrix. An experiment was established in coarse soil to evaluate if TERI datasets could quantify matrix and macropore hydraulic properties. Results show TERI as a viable method for calculating the fluid velocity along a series of vertical profiles in the coarse-grained North Carolina field site. The datasets allowed the distribution and hydraulic properties of the macropores to be quantified when compared with traditional soil datasets.