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D5073-21 – Standard Test Method Technical Guide
ASTM D5073-21 establishes standardized procedures for measuring the depth of surface water bodies. It encompasses three distinct methodologies: Manual Measurement (Procedure A), Electronic Sonic-Echo Sounding (Procedure B), and Electronic Nonacoustic Measurement (Procedure C). The practice is designed for use in quiescent or low-velocity flow environments and provides descriptive guidance rather than endorsement of specific equipment.
📏 Scope and Applicability
This practice provides comprehensive guidance on selecting appropriate depth measurement procedures and equipment. It is explicitly noted that for stream gauging applications, users should refer to Test Method D3858, while reservoir surveys are addressed in Guide D4581. The text specifies depth measuring terminology and outlines specific uses of electronic sounders.
💡 Technical Tip: When accurate depth data is required for discharge calculations in moving water, defer to the specific requirements of Test Method D3858 for open-channel flow measurement rather than relying solely on this overarching practice.
⚙️ Equipment and Terminology
The standard defines essential hydrographic terms. Familiarity with these definitions ensures consistent application of the practice across different field conditions and equipment types.
| 🟦 Term | 📖 Definition (D5073-21) |
|---|---|
| Beam Width | The angle in degrees of the main acoustic energy lobe emitted from a transducer. |
| Bar-Check | A method of determining depth by suspending a metal bar beneath a transducer on a marked line. |
| Sounding Line | A rope or cable used to support a weight lowered to determine depth. |
| Bottom Profile | A line trace representing the bottom surface beneath a water body. |
The three primary measurement procedures cover a broad spectrum of field instrumentation and are divided into specific sections within the standard:
| 📐 Procedure | ⚙️ Description | 📑 Sections |
|---|---|---|
| A: Manual Measurement | Physical contact using wading rods or sounding lines. | 6 – 11 |
| B: Electronic Sonic-Echo | Acoustic depth measurement via sonar transducers. | 12 – 13 |
| C: Electronic Nonacoustic | Depth measurement using pressure sensors or other non-sonar electronic methods. | 14 – 15 |
⚠️ Safety and Unit Standards
⚠️ Safety Advisory: This standard does not purport to address all safety concerns associated with its use. Users are responsible for establishing appropriate safety, health, and environmental practices, particularly when operating from survey vessels or near moving water.
The standard mandates that the values stated in inch-pound units are to be regarded as standard. Parenthetical SI unit conversions are provided for mathematical information only and are not considered standard. This practice was developed under internationally recognized standardization principles established by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
❓ Frequently Asked Questions
🔍 What is a bar sweep used for?
A bar sweep consists of bars or pipes suspended beneath a floating vessel, specifically designed to locate submerged snags or obstructions that may be hazardous to navigation.
💡 How does Electronic Sonic-Echo Sounding work?
Procedure B relies on sonar, which detects and locates submerged objects by analyzing sound waves they reflect. A transducer emits acoustic pulses and measures the return time to accurately calculate depth.
⚡ Which standard is referenced for depth measurements during stream gauging?
Test Method D3858 (Open-Channel Flow Measurement of Water by Velocity-Area Method) is the specific standard for depth measurement when tied directly to stream gauging and discharge calculations.
📌 Are inch-pound units required by D5073-21?
Yes. The values stated in inch-pound units (feet, inches) are regarded as the standard. SI unit conversions are provided in parentheses for information purposes only and are not considered standard.