ISO 3716:2021

Hydrometry - Functional requirements and characteristics of suspended-sediment samplers

This document specifies the functional requirements and characteristics of the different types of suspended-sediment samplers used for collecting water-sediment mixtures from streams, rivers, lakes and reservoirs. This document does not include equipment for collecting samples in closed conduits and wastewater discharges. NOTE The units of measurement used in this document are SI units.

Hydrométrie — Spécifications de fonctionnement et caractéristiques des appareils d'échantillonnage pour la détermination des charges sédimentaires en suspension

General Information

• Status: Published
• Publication Date: 17-Oct-2021
• ICS: 17.120.20 - Flow in open channels
• Technical Committee: ISO/TC 113/SC 6 - Sediment transport
• Drafting Committee: ISO/TC 113/SC 6/WG 4 - Revision of ISO 3716
• Current Stage: 6060 - International Standard published
• Start Date: 18-Oct-2021
• Due Date: 15-Mar-2021
• Completion Date: 18-Oct-2021

Relations

• Consolidated By: ISO 10062:2022 - Corrosion tests in artificial atmosphere at very low concentrations of polluting gas(es)
• Effective Date: 06-Jun-2022
• Revises: ISO/TS 3716:2006 - Hydrometry - Functional requirements and characteristics of suspended-sediment samplers
• Effective Date: 15-Jul-2017

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.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 3716
Second edition
2021-10
Hydrometry — Functional
requirements and characteristics of
suspended-sediment samplers
Hydrométrie — Spécifications de fonctionnement et caractéristiques
des appareils d'échantillonnage pour la détermination des charges
sédimentaires en suspension
Reference number
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements of samplers . 1
5 Characteristics of suspended-sediment samplers . 3
6 Types of samplers. 3
6.1 Open containers. 3
6.2 Vertical and horizontal cylinder instantaneous trap samplers . 3
6.3 Weighted bottle samplers . 4
6.4 Pumping samplers . 5
6.4.1 General . 5
6.4.2 Fixed-orifice pumping samplers. 5
6.4.3 Moveable-orifice samplers . 6
6.5 Single-stage samplers . 6
6.6 Point-integrating samplers . 7
6.7 Depth-integrating samplers . . 7
6.8 Clean samplers . . 8
6.9 Sand-flux samplers . 9
7 Models of samplers .10
Bibliography .13
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 6,
Sediment transport.
This second edition cancels and replaces the first edition (ISO/TS 3716:2006), which has been
technically revised. The main changes compared with the previous edition are as follows:
— the Scope has been clarified to include samplers for collecting water-sediment mixtures of rivers,
streams, lakes and reservoirs and exclude equipment for sampling closed conduits and wastewater
discharges;
— clauses on sampling techniques have been removed;
— the types and models of samplers have been expanded.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
Suspended-sediment samplers are used to collect a representative sample of the water-sediment
mixture of streams, rivers, lakes and reservoirs. Ideally, the sampler should be able to collect samples
that represent the mean concentration of suspended sediment or define the horizontal and vertical
variation of suspended-sediment concentration so that the mean concentration can be determined.
There are different types of samplers available for collecting suspended sediment, including some that
are appropriate for sampling in lakes and reservoirs and others that are used for sampling in streams
and rivers. Open containers, vertical and horizontal cylinders, bottle samplers and pumping samplers
are used primarily in lakes and reservoirs. Point-integrating samplers, depth-integrating samplers,
single-stage samplers and pumping samplers are used primarily in streams and rivers. Only samplers
that operate isokinetically can collect unbiased, representative samples of suspended sand-size
particles in streams and rivers. Some samplers have also been adapted to enable the collection of clean
(uncontaminated) samples of trace metal and organic compounds that are commonly associated with
suspended sediment in streams and rivers.
v
INTERNATIONAL STANDARD ISO 3716:2021(E)
Hydrometry — Functional requirements and
characteristics of suspended-sediment samplers
1 Scope
This document specifies the functional requirements and characteristics of the different types of
suspended-sediment samplers used for collecting water-sediment mixtures from streams, rivers, lakes
and reservoirs.
This document does not include equipment for collecting samples in closed conduits and wastewater
discharges.
NOTE The units of measurement used in this document are SI units.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 772, Hydrometric determinations — Vocabulary and symbols
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 772 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
isokinetic sampling
method of sampling where the intake velocity of the suspended-sediment sampler equals the ambient
stream velocity
4 Requirements of samplers
To ensure that the samples taken by a sampler are truly representative of the sediment concentration of
a stream at a point of sampling, the ideal sampler shall fulfil the following technical requirements.
a) The sampler shall be streamlined to reduce drag and to minimize disturbances to normal sediment
flow. Figure 1 shows an example of a typical streamlined sampler.
b) The velocity of inflow in the mouth of the sampler, nozzle or sampling tube shall be isokinetic or
as close as possible to the velocity of the current at the sampling point, irrespective of what this
velocity may be or irrespective of what the depth of submergence at this point may be.
c) The mouth/intake of the sampler shall always face into the current at the sampling point.
d) The mouth/intake of the sampler shall be outside the zone of the disturbances of the flow set up
by the body of the sampler and its operating gear, and the flow lines shall be disturbed as little as
possible, especially near the mouth.
Key
1 nozzle
2 body holding sample bottle
3 hanger
4 tail fin
Figure 1 — Typical depth-integrating sampler
e) Filling arrangements shall be smooth so that there is no sudden inrush of water-sediment mixture;
the air escaping from the sampler shall not hinder the entry of the sample; this necessitates a
separate port for air exhaust.
f) Point-type samplers shall be able to collect samples at the desired depth without the samples being
disturbed or contaminated by the water-sediment mixture at other points while the sampler is
being raised or lowered.
g) Point-type samplers shall be able to take a sample exactly when and where it is required.
h) The sampler shall be portable, yet sufficiently heavy to minimize deflection of the supporting cable
from the vertical due to current drag.
i) The sampler shall be simple in design and robust in construction and shall require minimum care
in maintenance and operation.
j) The removable-type container within the sampler shall be easily removed, readily capped or sealed
and easily transported to a laboratory without loss of contents. Alternatively, if the container forms
part of the sampler, it shall be installed to secure complete drainage of the contents.
k) The volume of the sample collected by the sampler shall be sufficient for determining the
concentration and size distribution of the sediment. The minimum sample size is generally 0,5 l.
l) The sampler shall be able to collect samples of water-sediment mixtures in streams and rivers
isokinetically over the depth, width, and velocity conditions to be sampled. If samples cannot be
collected isokinetically because water velocities are lower than the operating limits of sampler or
the velocity of the current is not known, large errors in the concentration of sand particles can
occur.
5 Characteristics of suspended-sediment samplers
Since the sampling conditions encountered in lakes, reservoirs, streams and rivers vary widely, a single
sampler for all the conditions cannot be recommended. Factors such as availability, cost and specific
requirements of the sampling also influence the choice of the sampler to a great extent. The different
types of samplers include open containers, vertical and horizontal cylinders, bottle samplers, pumping
samplers, single-stage samplers, point-integrating samplers and depth-integrating samplers. All these
types of samplers can collect a representative sample of the water-sediment mixture in a river or
stream under the right conditions, but many of them cannot be used in rivers with swift currents and
a non-uniform distribution of sediment concentration. For general use in rivers and streams, isokinetic
point-integrating and depth-integrating samplers are recommended. The use of trade, product or firm
names in this document is for descriptive purposes only and does not imply endorsement.
6 Types of samplers
6.1 Open containers
This type of sampler consists of an ordinary pail, can or open bottle. The sample is collected by
holding the container under the surface of the water or by lowering it to the water surface with a rope
or cable. The filled container can be sealed for transport and subsequent analysis or the sample can
be transferred into another container that can be sealed. Open-container samplers can only collect a
sample at the water surface and do not meet most of the requirements noted in Clause 4. Representative
samples are collected only if the water-sediment mixture is thoroughly mixed and contains negligible
coarse silt and sand.
It is important to limit any recirculation of water-sediment mixture while obtaining the sample in order
to limit sediment settling in the open container resulting in bias (high) errors.
6.2 Vertical and horizontal cylinder instantaneous trap samplers
These samplers (see Figures 2 and 3) are typically made of steel, brass or plastic. They are made
in various diameters and lengths. The cylinder is lowered to the desired sampling point with the
valves at each end of the cylinder in the open position. The sample is collected by closing the valves
and retrieving the cylinder. The valves are actuated by an electrical impulse or by sending a weight
down the suspension cable to trip spring-loaded valves. The sample is typically transferred to another
container, so the cylinder can be reused.
These samplers can collect samples at specific depths. The samples are instantaneous, rather than
integrated over any time or space. Under ideal conditions, they will collect a representative sample,
particularly if there is negligible coarse silt and sand. They are well suited to sampling lakes and
reservoirs and low velocity conditions in streams and rivers.
These samplers, particularly the vertical cylinders, offer considerable resistance to flow and are only
stable at very low velocities. Vertical cylinders cannot sample close to the streambed. Horizontal
samplers can sample near the streambed.
Figure 2 — Kemmerer sampler
Figure 3 — Van Dorn horizontal sampler
6.3 Weighted bottle samplers
There are many different variations of bottle samplers. They generally consist of a weighted container
to hold a 0,5 l to 2 l sample bottle. The sampler is lowered to the desired depth by a rope or cable and
then the cap is removed from the bottle to collect the sample. Some models have the capability of both
opening and closing the bottle cap, so the sample is sealed and no intermixing of the sample with the
water-sediment mixture occurs while the sampler is being retrieved.
These samplers are not isokinetic. If there is any intermixing, then concentrations can be biased
high because of sediment settling within the sample container. They are sometimes able to collect a
representative sample for low velocity, well mixed conditions.
These samplers offer considerable resistance to flow and are only stable at very low velocities. Samples
cannot typically be collected close to the streambed. The potential for intermixing of the sample and
water-sediment mixture in the river is high for those samplers that cannot be sealed at the sampling
point.
6.4 Pumping samplers
6.4.1 General
There are two types of pumping samplers used for collecting suspended-sediment samples: those with
a fixed orifice that are operated in automatic mode and those with a moveable orifice that are deployed
from a boat, cableway, walkway or bridge.
6.4.2 Fixed-orifice pumping samplers
Fixed-orifice samplers (see Figure 4) are typically used at sites where personnel are not available to take
samples manually, such as ephemeral and flashy streams or streams in isolated locations. The orifice
is typically located at or near the stream bank. The samplers are powered with line power or batteries,
and samples are pumped from the stream to sample containers using a vacuum pump, peristaltic pump
or submersible pump.
Sampling initiation and frequency are controlled based on time,
...