FIG. 10. Maps of bulk soil electrical conductivity measured with electromagnetic induction across a 12-ha field, rendered with 10- by 10-m pixels. (a) Dry soil before a major rainfall event, (b) soil after 75 mm of rain, and (c) the difference between the two. The field slopes from right to left, with the bottom-left corner the lowest point. The red areas in (a) and (b) indicate what appears to be the emergence of subsurface flow paths after rainfall. The red areas in (c) indicate zones of increased electrical conductivity after rainfall.