Hydrogeophysical Case Studies in the Vadose Zone

Abstract

The focus of this chapter is the characterization of the vadose zone, or the unsaturated section of the subsurface, using hydrogeophysical techniques. The regions of water saturation as they relate to the physical properties are shown for reference in Figure 14.1. Characterization below the water table (in the saturated section) is described in Chapter 13 of this volume and will not be discussed in detail here. From a physical properties perspective, the zones of variable saturation above the water table are transitional, and depend upon the soil or rock type and the lateral heterogeneity of the materials. In the vertical direction, the boundaries between all of these zones are dependent upon the types of soil, regolith, or rock that are present; the current and historical climatic conditions; and the regional and local geomorphology of the site. These same factors affect the heterogeneity of the vadose zone in the horizontal (lateral) direction and generally compound the problems of defining the different regions of moisture in the vadose zone.