What is ISO 1070 - Slope-area method about?
ISO 1070 is an international standard that discusses the attributes of hydrometry.
ISO 1070 specifies a method of determining discharge in open channels from observations of the surface slope and cross-sectional area of the channel.
ISO 1070 is applicable to use under special conditions when direct measurement of discharge by typically more accurate methods, such as the velocity-area method, is not possible. The method can be used to determine discharge:
- For a peak flow that left high-water marks along the stream banks
- For a peak flow that left marks on a series of water-level gauges or where peak stages were recorded by that series of gauges
- For flow observed at the time of determining gauge heights from a series of gauges
The method is commonly used to undertake the extension of stage-discharge relationships above the highest gauged flows.
Note: ISO 1070 does not apply to determining discharges in tidal reaches.
Who is ISO 1070 - Slope-area method for?
ISO 1070 on the slope-area method is relevant to:
- Hydrologists
- Geologists
- Civil engineers
- Groundwater level researchers
- Water resources engineers
Why should you use ISO 1070 - Slope-area method?
The slope–area method is an indirect method of determining discharge in open channels when direct measurement of the flow is not possible because of the timing of the flow or because the site is too hazardous for direct measurement techniques.
ISO 1070 assists the user with the method that is usually used to document the discharge of a flood and to extend the stage-discharge rating of a streamflow gauging station above direct measurements of discharge. This method can also be used at locations where bridge, cableway, or boat measurements are not possible. Water discharge is computed using flow resistance formulae based on channel characteristics, water-surface profiles, and a roughness or friction coefficient.
The slope–area method is most often used to document a flood or remarkably high flow event. The friction slope defined in the flow resistance formulae is approximated by surveying high-water marks on both banks within the measuring reach to determine the change in water surface elevation, determining the velocity heads at each section, and evaluating the loss due to contraction or expansion.
Overall, ISO 1070 is helpful as it provides guidance on the slope–area method that is most often used to document a flood or extremely high flow event. The friction slope defined in the flow resistance formulae is approximated by surveying high-water marks on both banks within the measuring reach to determine the change in water surface elevation, determining the velocity heads at each section, and evaluating the loss due to contraction or expansion.
What’s changed since the last update?
BS ISO 1070:2018 supersedes BS 36805:1992, which is withdrawn. The main changes compared to the previous edition are as follows:
- BS ISO 1070:2018 has been reorganized to first present two-section computations followed by multiple reach computations
- A third governing formula has been added
- Three annexes have been added
