breakthrough curves are often used to estimate model parameters, including effective porosity, finger width, Saprolite is a form of weathered bedrock that is commonly used as mobile zone porosity, and the retardation factor. Each the host material at waste disposal sites in the Southeastern Piedmont. However, estimating the unsaturated hydraulic and transport proper-approach provides valuable information about the beties of saprolite is difficult due to saprolite's low permeability. We havior of solute transport through unsaturated media. demonstrate the use of short-duration fluid irrigation pulses for main-Water potential responses are also used to estimate taining unsaturated conditions in intact saprolite columns. Concomihydraulic parameters (Inoue et al., 1998). In these cases, tant Cl Ϫ tracer experiments demonstrate that irrigated waters moved perturbations at the surface, from precipitation and irrithrough an effective volumetric porosity (0.038-0.108 cm 3 cm Ϫ3) subgation, and within the subsurface, from fluid injections stantially less than the ambient water-filled porosity (0.44 cm 3 cm Ϫ3). or removals, are monitored and used for parameter esti-We observed the unexpected result that irrigation-induced pressure mation. The unsaturated hydraulic conductivity, hywave velocities (1983-3670 cm d Ϫ1) were ≈ 1000 times faster than draulic diffusivity, or sorptivity are determined in these tracer velocities (2.04-6.00 cm d Ϫ1). The relationship between pressure wave velocities and fluid velocities is described using kinematic wave cases. Perturbations due to fluid injection or extraction, theory, presented for four parametric representations (Brooks-Corey, or the modification of the pressure head at a surface or van Genuchten-Mualem, Broadbridge-White, and the Galileo Numpoint, induce a step or spike change in fluid pressure ber), that predicts fluid pressure velocities to be from approximately that is transmitted through the unsaturated zone. The two to fifteen times faster than saprolite tracer velocities. None of pressure wave response, also called the kinematic the kinematic models was able to reproduce observed rapid pressure model, has been used to model subsurface stormflow wave velocities. A hydraulic form of the advection-diffusion equation (Beven, 1982), vertical flow through unsaturated soils based on Richards' equation is presented that favorably predicts the