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 (