5.2 Methods to Estimate Hydraulic Conductivity

There are many approaches to estimating hydraulic conductivity of earth materials. In a laboratory setting tests using the Darcy column set up can be performed to estimate values of hydraulic conductivity. If the material is unconsolidated, hydraulic conductivity can be estimated by analyzing the range of sizes of sediment grains. However, small-scale measurements often are not representative of the hydraulic conductivity at the much larger field scale as discussed in Section 3 of this book. Representative hydraulic conductivity values are needed in order to evaluate groundwater systems when designing facilities for water supply or to clean up contamination. Consequently, a large area of groundwater hydrology involves field testing to estimate hydraulic conductivities. A summary of laboratory methods for estimating hydraulic conductivity is provided in Box 4. Click here to read Box 4, which includes details about the basic laboratory procedures and a brief overview of field testing referred to as aquifer testing. Aquifer testing is covered in detail in numerous publications by the United States Geological Survey (e.g., Lohman 1972); groundwater text books; and commercial aquifer test software manuals and packages (e.g., AQTESOLV, and Aquifer Test). Regardless of the method employed, the value of hydraulic conductivity is an estimate, though it is often referred to as a measurement or determination.