Overview
ISO 4363:2002 - Measurement of liquid flow in open channels - specifies methods for measuring characteristics of suspended sediment in open-channel flows. It defines conventional and simplified procedures to determine the cross-sectional mean suspended sediment mass concentration and the mean particle size distribution. The conventional method is intended for routine monitoring under stable or slowly varying flows; the simplified method is for observing sediment variation processes and for use under difficult field conditions. The standard is applicable to measurements at hydrological stations and establishes empirical links between the two approaches.
Key topics and requirements
- Scope and principles: Discharge-weighted measurement of cross-sectional mean sediment mass concentration and particle size distribution; weighting by flow discharge across the cross-section.
- Measurement methods:
- Conventional method - discharge-weighted, for routine and stable-flow sampling.
- Simplified method - suitable for rapidly varying or difficult conditions; used to observe temporal changes.
- Sampling design: Selection of site and division of cross-sections into segments/verticals; methods for combining samples collected across a cross-section (segmental discharge-weighted principle).
- Samplers and instruments: Requires samplers conforming to ISO 3716 and recommends time-integration samplers plus in-situ velocity measurement devices to reduce variability.
- Units and reporting: Uses SI units (mg/l, g/l, kg/m3) and defines mass concentration, volume fraction and mass fraction expressions.
- Calculations and uncertainty: Procedures to compute sediment discharge, cross-sectional mean concentration, particle size distribution, and methods for estimating random uncertainty and systematic error.
- Supporting annexes: Informative annexes detail data collection for error estimation and procedures/examples for combining cross-sectional samples.
Applications and users
ISO 4363:2002 is used where accurate suspended-sediment characterization is required:
- River and stream monitoring programs at hydrological stations
- Reservoir siltation assessments and sediment budget studies
- Erosion and catchment management, navigation-channel maintenance
- Calibration and validation of sediment transport models
- Environmental impact assessments and regulatory monitoring
Primary users include hydrologists, environmental and water resources engineers, river basin managers, researchers, and agencies conducting sediment monitoring programs.
Related standards
- ISO 3716 - samplers for suspended sediment load
- ISO 4365 - methods for concentration and particle size distribution analysis
- ISO 748 - velocity-area methods for open channels
- ISO 772, ISO 31, ISO 1000 - vocabulary, units and SI recommendations
Keywords: ISO 4363:2002, suspended sediment, open channels, cross-sectional mean sediment mass concentration, particle size distribution, hydrological stations, sediment sampling, sediment transport, measurement uncertainty.
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