Overview
ISO 3716:2021 - "Hydrometry - Functional requirements and characteristics of suspended‑sediment samplers" defines the functional requirements and characteristics for samplers that collect suspended‑sediment (water‑sediment mixtures) from streams, rivers, lakes and reservoirs. The standard clarifies scope (excludes closed conduits and wastewater discharges), uses SI units, and updates earlier guidance to reflect a broader range of sampler types and models.
Key topics and technical requirements
- Sampling performance: Samplers should be designed to collect representative samples of suspended sediment; only isokinetic sampling (sampler intake velocity equal to ambient stream velocity) can avoid bias for sand‑size particles.
- Design requirements:
- Streamlined bodies to reduce drag and minimize flow disturbance.
- Intake orientation: mouth/nozzle must face into the current and remain outside the sampler’s disturbance zone.
- Smooth filling and air exhaust: separate air port to avoid sudden inrush or trapped air that would disturb the sample.
- Portability and robustness: lightweight for handling but heavy enough to resist current drag; simple construction for easy maintenance.
- Sample handling: removable or drainable containers that can be sealed and transported without loss of contents; minimum sample volume generally 0.5 L for concentration and size‑distribution analyses.
- Operational capabilities:
- Point samplers must take samples at precise depths/times without contamination during retrieval.
- Samplers should be capable of collecting isokinetic samples over the depth, width and velocity range of interest; non‑isokinetic operation can introduce large errors.
- Types and characteristics: detailed characteristics for open containers, vertical/horizontal cylinder trap samplers (e.g., Kemmerer, Van Dorn), weighted bottle samplers, pumping samplers (fixed‑ and moveable‑orifice), single‑stage, point‑integrating, depth‑integrating, clean samplers and sand‑flux samplers.
Applications and users
ISO 3716:2021 is essential for:
- Hydrologists and sediment transport researchers conducting suspended‑sediment monitoring
- Water resource and reservoir managers assessing sediment loads and reservoir infill
- Environmental and civil engineers involved in erosion, dredging and habitat studies
- Field technicians and laboratories performing suspended‑sediment concentration and grain‑size analyses
- Manufacturers and purchasers of hydrometric sampling equipment seeking compliance and performance guidance
Practical applications include routine monitoring, stormflow sampling (including automated fixed‑orifice pumping samplers), reservoir and lake profiling, and collection of clean samples for trace metal or organic association studies.
Related standards
- ISO 772 (Hydrometric determinations - Vocabulary and symbols) is referenced for terms and definitions used in ISO 3716:2021.
Open preview (PDF)Hydrometry — Functional requirements and characteristics of suspended-sediment samplers
