【国外标准】 Standard Guide for Sampling Fluvial Sediment in Motion

4.1 This guide is general and is intended as a planning guide. To satisfactorily sample a specific site, an investigator must sometimes design new sampling equipment or modify existing equipment. Because of the dynamic nature of the transport process, the extent to which characteristics such as mass concentration and particle-size distribution are accurately represented in samples depends upon the method of collection. Sediment discharge is highly variable both in time and space so numerous samples properly collected with correctly designed equipment are necessary to provide data for discharge calculations. General properties of both temporal and spatial variations are discussed.1.1 This guide covers the equipment and basic procedures for sampling to determine discharge of sediment transported by moving liquids. Equipment and procedures were originally developed to sample mineral sediments transported by rivers but they are applicable to sampling a variety of sediments transported in open channels or closed conduits. Procedures do not apply to sediments transported by flotation.1.2 This guide does not pertain directly to sampling to determine nondischarge-weighted concentrations, which in special instances are of interest. However, much of the descriptive information on sampler requirements and sediment transport phenomena is applicable in sampling for these concentrations, and 9.2.8 and 13.1.3 briefly specify suitable equipment. Additional information on this subject will be added in the future.1.3 The cited references are not compiled as standards; however they do contain information that helps ensure standard design of equipment and procedures.1.4 Information given in this guide on sampling to determine bedload discharge is solely descriptive because no specific sampling equipment or procedures are presently accepted as representative of the state-of-the-art. As this situation changes, details will be added to this guide.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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 12.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.