Land resource units that are defined by their physical properties can be characterized quantitatively using engineering test data. Information about substrate properties in quantitative terms confirms and augments qualitative statements about the physical characteristics of land resource units.

Ground-water resources in the Corpus Christi area-Nueces, San Patricio, Refugio, and Aransas Counties (fig. 1)-were investigated as part of a broader study of land and water resources of the four-county area (Kier and others, 1974a and 1974b; Kier and White, in preparation).