1.1 This guide describes techniques that may be used to quantify the soil-water (or soil-moisture) flux, the soil-water movement rate, and/or the recharge rate within the vadose zone. This guide is not intended to be all-inclusive with regard to available methods. However, the techniques described do represent the most widely used methods currently available.

1.2 This guide was written to detail the techniques available for quantifying soil-moisture flux in the vadose zone. These data are commonly required in studies of contaminant movement and in estimating the amount of water replenishing a renewable ground-water resource, that is, an aquifer. State and federal regulatory guidelines typically require this information in defining contaminant travel times, in performance assessment, and in risk assessment. Both unsaturated and saturated flow modelers benefit from these data in establishing boundary conditions and for use in calibrations of their computer simulations.

1.3 This standard is one of a series of standards on vadose zone characterization methods. Other standards have been prepared on vadose zone characterization techniques.

1.4 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word "Standard" in the title of this document means only that the document has been approved through the ASTM consensus process.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.