ISO/TR 11328:1994

Overview

ISO/TR 11328:1994 – Measurement of liquid flow in open channels: Equipment for the measurement of discharge under ice conditions, is a Technical Report developed by the International Organization for Standardization (ISO). This document provides comprehensive guidance on the specialized equipment required for measuring water discharge in rivers and open channels during periods when ice cover is present. Notably, it focuses on the physical tools and devices needed to gain access through the ice layer and collect crucial area and velocity data for the accurate determination of flow under challenging winter conditions.

It is important to note that ISO/TR 11328:1994 does not specify the detailed measurement or computation techniques themselves-those are addressed in other International Standards, particularly ISO 9196. Instead, this Technical Report is intended to be used in conjunction with such procedural standards.

Key Topics

• Ice Cutting and Drilling Equipment: Guidance on types of ice chisels, manual and motorized ice drills necessary for creating access holes in ice covers.
• Current Meters: Descriptions of current meters, such as cup-type and propeller-type, adapted for operation under ice, and advice on avoiding inaccuracies due to clogging or freezing.
• Depth and Thickness Measurement Tools:
  • Wading rods and cable suspension equipment for measuring water depth and ice thickness.
  • Sounding reels and specialized weights for current meter deployment.
• Support and Safety Equipment:
  • Rod holders, slush removers, and ice creepers for secure operation and improved safety on slippery surfaces.
  • Equipment sleds and toboggans for transporting gear in remote or snow-covered locations.
• Tracer Dilution Methods: Overview of equipment for tracer injection and sample retrieval in dilution-based discharge measurement.
• Flow Control Structures: Equipment for maintaining and operating notches, weirs, and flumes under icy conditions, including manual and powered ice removal devices.
• Ice Prevention Systems: Brief mention of heating and air-bubbling systems to prevent ice buildup at measurement sites.

Applications

ISO/TR 11328:1994 is invaluable for hydrologists, field technicians, and environmental agencies tasked with hydrometric surveys and streamflow measurement in cold regions. Its recommendations ensure that:

• Reliable open channel flow measurements can continue throughout winter, supporting effective water resource management, flood forecasting, and environmental monitoring.
• Survey teams are equipped with suitable and safe tools to access, operate, and maintain measurement sites even in severe ice-covered conditions.
• The integrity and accuracy of discharge data are preserved by specifying the right equipment for ice breakthrough, sample collection, and velocity-area assessments.
• Practitioners can efficiently prepare for fieldwork by selecting proper depth rods, current meters, tracer equipment, and support gear, as outlined in the report.

Related Standards

ISO/TR 11328:1994 is closely linked with a range of other international standards that address measurement processes and definitions:

• ISO 9196: Liquid flow measurements under ice conditions – specific measurement methods and computation.
• ISO 748: Velocity-area methods for liquid flow measurement in open channels.
• ISO 772: Vocabulary and symbols for liquid flow measurement.
• ISO 1100-1 & ISO 1100-2: Establishment, operation, and stage-discharge relationships for gauging stations.
• ISO 2537: Cup-type and propeller-type current meters.
• ISO 3454 & ISO 3455: Depth sounding and calibration of rotating-element meters.
• ISO 9555 Series: Tracer dilution methods for steady flow measurements.

Practical Value

Utilizing ISO/TR 11328:1994 ensures accurate, safe, and efficient discharge measurements in ice-affected channels. The standard supports the continuity of hydrological data collection-crucial for managing freshwater resources and mitigating risks in cold climate regions. Its practical recommendations on specialized measuring instruments, site access, and equipment care are essential for conducting reliable open channel flow surveys under demanding ice conditions.