D5130-95 – Standard Test Method Technical Guide

The ASTM D5130-95 (Reapproved 2014) standard provides a rigorous methodology for the indirect measurement of water discharge in open channels and streams using the slope-area method. This technique is essential for quantifying peak flood discharge when direct measurements are hazardous or impossible. By leveraging representative cross-sectional geometry, water-surface slope, and channel roughness, hydrologists can reconstruct the maximum discharge of a specific flow event.

📐 Scope and Context of the Slope-Area Method

This test method covers the computation of discharge (the volume rate of flow) of water in open channels or streams using representative cross-sectional characteristics, the water-surface slope, and coefficient of channel roughness as input to gradually-varied flow computations. The method produces an indirect measurement of the maximum discharge for one flow event, usually a specific flood. The computed discharge may be used to help define the high-water segment of a stage-discharge relation. According to Section 1.3, the values stated in inch-pound units are to be regarded as standard, while the values given in parentheses are mathematical conversions to SI units provided for information only.

⚙️ Key Computational Parameters and Procedure

The slope-area method relies on carefully defined parameters for accuracy. Key among these is the conveyance (K), which defines the carrying capacity of a channel. It is