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Fig. 2. A horizontal pavement located approximately 3 m directly beneath a ponded infiltration test in which about 790 L of dyed water were applied to an initially dry fracture network. The grid lines are located at 0.305-m (1-foot) horizontal intervals. Low permeability of the rock matrix in this densely welded tuff unit near Yucca Mountain, Nevada constrained flow to the fracture network. Well-connected near-vertical features dominate the network, with fewer extensive subhorizontal fractures. The infiltrating fluid slug flooded the near-surface network and then fragmented during the transition to unsaturated flow. Here we see a highly nonuniform distribution of the dye tracer (blue). Flow occurred along only portions of some fractures and avoided others altogether, despite obvious connection. There is also evidence of focused flow along some, but not all, of the vertical intersections (from Nicholl and Glass, 2002).
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50 h) that was conducted in fluvial channel deposits near Albuquerque, NM. Flagged nails in the outcrop are spaced 40 cm apart. Dyes introduced with the infiltrating water illustrate some of the complex processes affecting flow and transport in the vadose zone. Lateral spreading occurs above a capillary barrier (gravel deposits). Dye is transported preferentially along a fracture, while the inclined stratification focuses flow and influences dye transport.