# 5 Hydraulic Conductivity Values

The value of hydraulic conductivity, *K*, is determined by measuring flow rates, lengths, water levels, and pressures (Equation 15). Resulting hydraulic conductivity values are also used in conjunction with equations to compute groundwater discharge (Equation 15), flux (Equation 17), and velocity (Equation 18) as illustrated in Section 4. Hydraulic conductivity values are also required to predict the three-dimensional head distribution in a groundwater basin, infer groundwater flow directions and anticipate groundwater impacts from municipal well fields. This section:

- describes some basic methods used to estimate hydraulic conductivities in the laboratory;
- provides an illustration showing the range of hydraulic conductivities for of various earth materials;
- presents concepts used to describe the two- and three-dimensional spatial variability of hydraulic conductivity, including the spatial concepts of isotropic, anisotropic, homogeneous and heterogeneous hydraulic conductivity distributions;
- discusses methods used to assign hydraulic conductivities to field settings; and,
- explains methods to determine equivalent hydraulic conductivities for fractured systems and individual fractures.