5.1 A variety of methods exist for this measurement. Each method has its specific applicability, limitations, and levels of complexity. The users of this guide should use the descriptions of the various methods to choose the procedure, which most closely meets their needs. Most of these methods are not intended to predict sediment yield ( 6 ) .

5.2 These methods are used to estimate the soil loss (in mass of soil/unit area/unit time) from rainfall and snow melt for site-specific factors due to rill and interrill erosion. These methods can not be used to estimate soil loss from ephemeral gully or channel erosion.

5.3 The estimates resulting from the methods in this guide do not constitute a design for control of erosion. However, the outputs of these methods may be important input into such a design.

1.1 This guide describes methods used for estimating soil losses due to rill and interrill erosion. All known methods for water erosion with a sediment yield component are listed. This guide provides complete reference citations for the various methods currently used to estimate soil loss by rill and interrill erosion. The referenced methods contain the rationale and detailed procedures for determining rill and interrill soil loss. For each method listed, specific applicability, limitations, and level of complexity are briefly outlined in terms of the relative spatial scale, land use, hydrology, erosion, time scale, input requirements, and output.

1.2 The referenced methods were developed for specific uses and may not be applicable in all cases. For example, some of the values derived by these methods estimate the amount of soil movement on a field without re-deposition while others account for re-deposition and estimate off-field sediment yield. Most of these methods are not intended to predict sediment yield.

1.3 Metric (SI) Units. Some of the methods in this guide are written in the preferred English units. A discussion of the conversion of the final answer to metric units is included in paragraph 6.2 .

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 guide cannot replace education or experience and should be used in conjunction with professional judgement. Not all aspects of this guide may be applicable in all circumstances. This guide 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 guide be applied without consideration of a project's many unique aspects. The word Standard in the title of this guide 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.