Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D5906-21 – Standard Test Method Technical Guide
📐 Scope and Applicability of D5906-21
ASTM D5906-21 is a Standard Guide that provides a descriptive framework for selecting and applying procedures to establish the horizontal position of a depth measurement in a surface water body. The guide is specifically intended for quiescent or low-velocity flow environments. It covers three distinct measurement procedures: Manual Measurement (Sections 7–12), Optical Measurement (Sections 13–17), and Electronic Measurement (Sections 18–27).
The narrative specifies horizontal positioning terminology and describes various equipment and techniques without endorsing any particular manufacturer. Values stated in inch-pound units are regarded as standard within this guide; SI unit conversions are provided for information only.
| 🟦 Procedure | 📏 Description | 🎯 Typical Application |
|---|---|---|
| Procedure A — Manual Measurement (Sections 7–12) |
Utilizes physical tapes, tag lines, or range markers for position fixing off a baseline. | Small streams or low-velocity flows where high accuracy is needed over short distances. |
| Procedure B — Optical Measurement (Sections 13–17) |
Employs transits, theodolites, or total stations (EDM) to determine angles from a baseline. | Calm rivers, lakes, and reservoirs where a clear line-of-sight is available. |
| Procedure C — Electronic Measurement (Sections 18–27) |
Uses GPS, Electronic Positioning Systems (EPS), or continuous wave radio systems for direct coordinate determination. | Large water bodies, wide area mapping, and environments requiring frequent real-time positioning updates. |
⚙️ Measurement Procedures and Key Equipment
When conducting surveys under this guide, the selection of a measurement procedure depends on the specific environmental conditions and required precision. Manual methods rely on establishing a physical baseline and taking direct measurements. Optical methods improve range and accuracy by utilizing angle measurements from a known baseline. Electronic methods, including Electronic Distance Measurement (EDM) and the Global Positioning System (GPS), provide the highest efficiency for open-water surveys by determining Cartesian coordinates (x, y, z) using radio signal propagation from satellites or ground-based stations.
The standard does not stand alone; it is an integral part of a suite of standards for water and sediment measurement. Users are directed to consult referenced standards such as D1129 (Terminology Relating to Water), D3858 (Velocity-Area Method), and D5073 (Depth Measurement of Surface Water) to ensure a cohesive measurement program.
💡 Tip: This guide is descriptive and does not mandate specific equipment. Users should evaluate the resolution of their chosen positioning system relative to the flow velocity and channel width to ensure the horizontal position error does not dominate the total uncertainty of the depth measurement.
📊 Standard Terminology and Definitions
D5906-21 establishes critical terminology to ensure consistency across manual, optical, and electronic surveying methods. The definitions below are adapted from Section 3.2 of the standard and supporting documents.
| 📌 Term | ⚡ Definition (per Section 3.2 of D5906-21) |
|---|---|
| Accuracy | Refers to how close a measurement is to the true or actual value. |
| Baseline | The primary reference line for use in measuring azimuth angles and positioning distances. |
| Electronic Distance Measurement (EDM) | The measurement of distance using pulsing or phase comparison systems. |
| Global Positioning System (GPS) | A satellite-based EDM system used in determining Cartesian coordinates (x, y, z) of a position by means of radio signals from NAVSTAR satellites. |
| Continuous Wave System | An electronic positioning system in which the signal transmitted between the transmitter and responder stations travels as a wave having constant frequency and amplitude. |
⚠️ Safety Note: Per Section 1.6 of the standard, this guide does not purport to address all safety concerns. It is the responsibility of the user to establish appropriate safety, health, and environmental practices and to determine the applicability of regulatory limitations prior to use.
❓ Frequently Asked Questions
🔍 What is the primary scope of ASTM D5906-21?
The standard covers the selection of procedures (Manual, Optical, and Electronic) commonly used to establish a measurement of horizontal position during investigations of surface water bodies. It is designed for determining the horizontal position of a depth measurement in quiescent or low velocity flow.
💡 Which referenced ASTM standards are key for developing a complete measurement program?
Key referenced standards include D1129 (Terminology Relating to Water), D3858 (Test Method for Open-Channel Flow Measurement of Water by Velocity-Area Method), D4410 (Terminology for Fluvial Sediment), and D5073 (Practice for Depth Measurement of Surface Water). These provide crucial context for flow, sediment, and depth data collection.
⚡ How does the standard define “Electronic Positioning System (EPS)”?
An Electronic Positioning System (EPS) is defined in Section 3.2.5 of the standard as a system that receives two or more Electronic Distance Measurements (EDM) to obtain a position.
📌 Under which ASTM subcommittee is this guide maintained?
This guide is under the jurisdiction of ASTM Committee D19 on Water and the direct responsibility of Subcommittee D19.07 on Sediments, Geomorphology, and Open-Channel Flow. The current edition was approved in November 2021 and published in June 2022.