1.1 本试验方法涵盖使用代表性横截面特征、上游最横截面的水面高程和渠道粗糙度系数作为输入逐渐变化的流量计算的明渠或溪流中的水流量计算。 2. 1.2 该试验方法可间接测量一次水流事件（通常为特定洪水）的流量。计算流量可用于定义水位流量关系上的点。 1.3 以英寸-磅为单位的数值应视为标准值。括号中给出的值是到国际单位制的数学转换，仅供参考，不被视为标准值。 1.4 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 当无法通过某种类型的流量计直接测量流量（例如在高流量条件下）以获得速度时，该试验方法特别适用于确定流量，并使用测深重量来确定横截面（参考试验方法 D3858 ). 该测试方法只需要一个高水位，与斜坡区域测试方法不同，该方法需要许多高水位线来定义河段的落差。它可以用于确定水位流量关系，而无需来自多个高水位事件的数据。 5.1.1 鼓励用户验证理论阶段- 尽可能与直流电表测量的放电关系。 5.1.2 为了绘制额定曲线，在额定曲线上绘制多个放电的阶段与放电以及它们的计算阶段以及直流电表测量值。

1.1 This test method covers the computation of discharge of water in open channels or streams using representative cross-sectional characteristics, the water-surface elevation of the upstream-most cross section, and coefficients of channel roughness as input to gradually-varied flow computations. 2 1.2 This test method produces an indirect measurement of the discharge for one flow event, usually a specific flood. The computed discharge may be used to define a point on the stage-discharge relation. 1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.4 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. 1.5 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. ====== Significance And Use ====== 5.1 This test method is particularly useful for determining the discharge when it cannot be measured directly (such as during high flow conditions) by some type of current meter to obtain velocities and with sounding weights to determine the cross section (refer to Test Method D3858 ). This test method requires only one high-water elevation, unlike the slope-area test method that requires numerous high-water marks to define the fall in the reach. It can be used to determine a stage-discharge relation without data from several high-water events. 5.1.1 The user is encouraged to verify the theoretical stage-discharge relation with direct current-meter measurements when possible. 5.1.2 To develop a rating curve, plot stage versus discharge for several discharges and their computed stages on a rating curve together with direct current-meter measurements.