Skip to main content

ISO 18481:2017

Current Date published:

Hydrometry — Liquid flow measurement using end depth method in channels with a free overfall

ISO 18481:2017 specifies a method for the estimation of the sub-critical flow of clear water in a smooth, essentially horizontal channel (or a gently sloping channel), abruptly discontinued at bottom by a hydraulic structure, with a vertical drop and discharging freely. Such an overfall forms a control section and offers a means for the estimation of flow using the end depth measurement method. A wide variety of channel cross-sections with overfall have been studied, but only those which have received general acceptance after adequate research and testing, and therefore do not require in situ calibration, are considered. This document covers channels with the following types of cross-sections:

a) rectangular with confined and unconfined nappe;

b) trapezoidal;

c) triangular;

d) circular;

e) parabolic.

The flow at the brink is curvilinear; therefore, the measured depth at the drop is not equal to the critical depth as computed by the principle based on assumption of parallel flow. However, the end depth and the critical depth (as in the case of the assumption of parallel flow) have unique relation, which is used to estimate the flow through these structures.

Get this standard Prices exclude GST
PDF ( Single user document)
$185.62 NZD
HardCopy
$185.62 NZD
Networkable PDF
Price varies
Preview only close
Prev {{ page }}/ {{ numPages }} Next
Preview only close
Prev {{ page }}/ {{ numPages }} Next
Pages: 20

Keep me up-to-date

Sign up to receive updates when there are changes to this standard

Related Information

Similar Standards

  • BS 3680-10B:1980

    Measurement of liquid flow in open channels. Sediment transport, Measurement of suspended sediment

  • BS 3680-10C:1996

    Measurement of liquid flow in open channels. Sediment transport, Guide to methods of sampling of sand-bed and cohesive-bed materials

  • BS 3680-10E:1993

    Measurement of liquid flow in open channels. Sediment transport, Sampling and analysis of gravel bed material

  • BS 3680-2A:1995

    Measurement of liquid flow in open channels. Dilution methods, General

Preview only close
Prev {{ page }}/ {{ numPages }} Next
Preview only close
Prev {{ page }}/ {{ numPages }} Next
Pages: 20

ISO 18481:2017

Get this standard Prices exclude GST
PDF ( Single user document)
$185.62 NZD
HardCopy
$185.62 NZD
Networkable PDF
Price varies

Request to add this standard to your subscription

ISO 18481:2017

Price varies
Online library subscription

Click "Send request for subscription" to request for your Account Administrator to add this standard to your subscripiton.

Cancel