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Two Standards are combined thatexplain the critical factor of saturated hydraulic conductivity to effectively and accurately measure groundwater flow and transport of contaminants. All saturated hydraulic conductivity measurements are subject to variability—even in the most geologically homogeneous aquifers—caused by local fluctuations in an aquifer's textural characteristics. Averages of these fluctuations constitute a set of values that can be subsumed into a more general probabilistic description of the sample by means of a probability density function. Applying probabilistic procedures to the saturated hydraulic conductivity produces the effective hydraulic conductivity, which can be used to estimate the average specific discharge, the average linear velocity, and other key variables in groundwater flow. The formulas in this publication must be written in the same units, S.I. or customary.

ASCE/EWRI Standard 50-08 provides current guidelines for fitting saturated hydraulic conductivity using probability density functions. Standard ASCE/EWRI 51-08 addresses the calculation of effective saturated hydraulic conductivity (K_e or K_ew) in local-scale groundwater flow, whether or not it is isotropic. Gathered in a single volume, these two Standard are the first in an anticipated series that will address the knowledge of probabilistic characterization and behavior of saturated groundwater conductivity.

These Standards will be useful to environmental engineers, water resources engineers, and any professional who uses hydraulics in engineering.