Overview - ISO 8368:2019 (Hydrometric determinations, flow measurements in open channels)
ISO 8368:2019 provides practical guidelines for selecting flow measuring structures (weirs, flumes, gates, etc.) used to measure liquid flow in open channels. The third edition (2019) updates the list of recommended structures, clarifies limitations and uncertainties, and expands guidance on whole-life cost and environmental impacts. Content is written in straightforward, non‑technical language to help users choose an appropriate measuring structure without requiring deep fluid‑mechanics expertise.
Key topics and requirements
- Types of structures covered: thin‑plate weirs (rectangular, V‑notch), broad‑crested weirs (round‑nose, rectangular, V‑shaped), triangular‑ and trapezoidal‑profile weirs, flumes (rectangular, trapezoidal, U‑throated, Parshall/SANIIRI), end‑depth methods, vertical/radial gates, compound gauging structures and fish passes.
- Selection factors: intended purpose, flow range, required accuracy, risk of afflux and submergence, channel size and nature, channel slope and sediment load, operation/maintenance/repair constraints, fish passage requirements, and whole‑life cost.
- Performance parameters: the standard provides values and guidance on relevant parameters describing limitations and measurement uncertainty for each structure type (users are directed to the specific standards for definitive hydraulic details).
- User‑oriented approach: written to make choice accessible to non‑specialists; it does not replace the detailed hydraulics or civil engineering specifications found in the individual structure standards.
Practical applications
ISO 8368:2019 is applicable where reliable open‑channel flow measurement is required, including:
- Water resources monitoring and management
- Wastewater and treatment plant flow control
- Environmental compliance and river monitoring
- Irrigation and drainage channel gauging
- Research, hydraulic studies, and facility design
Practical benefits include improved selection of measurement structures that balance accuracy, maintenance, environmental impact, and cost over the structure’s lifetime.
Who should use this standard
- Hydrologists, hydraulic and civil engineers
- Water utility and wastewater managers
- Environmental protection agencies and regulators
- Consultants specifying gauging installations
- Laboratory and field researchers conducting flow measurements
Related standards
- ISO 772 (Hydrometry - Vocabulary and symbols) is normative for terms and definitions used by ISO 8368.
- ISO 8368 lists individual, structure‑specific standards (Table 1) that provide detailed hydraulic and construction requirements. Users should consult those documents for design and installation specifications.
Keywords: ISO 8368:2019, hydrometric determinations, flow measurements, open channels, weirs, flumes, flow measuring structures, selection guidelines, measurement uncertainty, hydrometry.