ISO 11329:2001

Overview

ISO 11329:2001 - Hydrometric determinations: Measurement of suspended sediment transport in tidal channels provides standardized methods and practical guidance for sampling suspended sediment and estimating sediment transport rates in natural and man‑made channels affected by tidal action. Published by ISO in 2001 (second edition), the standard addresses the special hydraulic and sedimentary complexities of estuaries, creeks and tidal channels where flow reversals, density differences and spatial stratification occur.

Key topics and technical requirements

• Scope and purpose: Methods for sampling suspended sediment and calculating transport rates in tidal regimes influenced by both sea and freshwater flows.
• Observation duration: Long‑term, continuous measurements are required; for regular semidiurnal tides an observation period of about one full tidal cycle (~13 h) is recommended, and for diurnal or strongly mixed tides a 25 h period is advised.
• Sampling frequency and timing: Time between repeated observations at a point should be kept short (≤ 0.5 h). Velocity and water sampling must be simultaneous; velocity records should use ~1‑minute integration and at least three replicates.
• Sampling geometry: Cross‑sections should be divided into equally spaced verticals (e.g., at 0.25W, 0.5W, 0.75W or 0.2W, 0.4W,… where W = channel width). Sampling depths on a vertical typically at 0.2z, 0.4z, 0.6z, 0.8z and near surface/bed; for shallow water (<10 m) use near‑surface, mid‑depth and near‑bed.
• Sample type and volume: Point (integrating‑point) sampling is preferred over depth‑integrated gear in tidal channels; individual samples should be large enough (≥ 1 L) - pumped sampling is recommended.
• Site selection: Prefer sections without strong flood/ebb divergence, no abrupt bed changes, moderate bank slope and minimum low‑water depth (≈2 m desirable).
• Data handling: Correct velocity records to a common instant per ISO 2425; do not apply time corrections to sediment concentration - use closely timed sampling instead. Repeat observations to reduce scatter inherent to tidal systems.

Practical applications and users

ISO 11329:2001 is used by:

• Coastal and estuarine engineers assessing channel stability, dredging requirements and navigation projects
• Hydrologists and sedimentologists monitoring suspended sediment transport and morphological change
• Port authorities, environmental consultants and regulators planning reclamation, disposal sites and impact assessments
• Researchers and modelers who need field protocols and quality‑controlled datasets for calibration and validation of tidal sediment transport models

Related standards

• ISO 772 - Hydrometric determinations: Vocabulary and symbols
• ISO 2425 - Measurement of liquid flow in open channels under tidal conditions

Keywords: ISO 11329:2001, suspended sediment transport, tidal channels, hydrometric determinations, sediment sampling, tidal flow measurements, estuary sediment.