Overview
EN ISO 18365:2013 - Hydrometry - Selection, establishment and operation of a gauging station (ISO 18365:2013) provides requirements and guidance for planning, installing and operating gauging stations used to measure water level (stage) and discharge in lakes, reservoirs, rivers, canals and other open channels. The standard covers stage‑only stations, stage–discharge stations (including those with hydraulic structures), direct‑discharge measurements in natural channels, and special procedures for difficult conditions (for example ice, weed growth and extreme sedimentation). It also describes operational, calibration and maintenance expectations for reliable hydrometric data.
Key topics and requirements
- Scope and purpose: Defines when and how to measure stage and/or discharge to meet user needs for range, timeliness and uncertainty.
- Pre‑installation requirements: Identify required level/flow ranges, data types, allowable uncertainty, life expectancy, budget, and access/permit arrangements.
- Site selection considerations: Accessibility, hydraulic uniformity, bed/embankment stability, influence of wind, proximity to outlets, potential submergence, karst losses, vandalism, and future hydraulic works.
- Types of gauging stations:
- Stage‑only gauges (manual and recording)
- Stage–discharge stations in natural channels (rating curves)
- Stage–discharge stations with artificial hydraulic structures (weirs, flumes)
- Velocity‑discharge (direct) stations using measurement technologies
- Velocity and instrument methods: Guidance on instrument selection and calibration for methods such as Doppler, acoustic (transit time and echo correlation), and electromagnetic velocity measurement where applicable.
- Difficult conditions: Procedures and requirements for measurements under ice, heavy vegetation, or high sediment transport.
- Operation & maintenance: Periodic calibration, routine inspection, data recording/communication, and maintenance planning to sustain data quality.
- Supporting content: Annex on applicable conditions for choosing a discharge measurement method and normative reference to ISO 772 (vocabulary).
Applications and who uses it
EN ISO 18365 is essential for:
- Hydrologists and water resources engineers designing gauging networks
- Environmental and water quality agencies monitoring surface water flow and levels
- Flood forecasting and warning services deploying reliable stage sensors
- Dam and reservoir operators needing validated discharge and stage records
- Consultants and instrumentation suppliers specifying and commissioning gauging stations
- Researchers and modelers requiring standardized, traceable hydrometric data
Keywords: hydrometry standard, ISO 18365, gauging station, stage measurement, discharge measurement, flow in open channels, stage‑discharge rating, velocity‑discharge methods.
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