Open Channel Flow: Methods, Applications, and New Developments - Part 1

Open Channel Flow: Methods, Applications, and New Developments

By Jesse L. Yoder, Flow Research, Inc.

Growing environmental regulations and the increasing importance of water as a natural resource are generating growing interest in measuring flow in open channels. Flow in open channels, or conduits, is contrasted with flow in closed pipes. Measurement of flow in closed pipes is very common in industrial and process control environments, and many different types of meters are used for this purpose. Open channel flow measurement occurs in industrial applications, but it also is very common in towns and municipalities that monitor drinking water and wastewater treatment flows.

One way to understand the difference between open channel and closed pipe flow is to think of it as the difference between gravity-induced and pressurized flow. Flow in uncovered channels such as irrigation ditches depends on gravity. Likewise, flow in partially filled closed conduits, such as culverts and drain pipes, also is gravity-dependent. Flow in closed pipes for industrial applications occurs under pressure. So open channel flow might be called gravitational flow, while closed pipe flow could be called pressurized flow. This explains why flows in both uncovered conduits and partially filled pipes are considered to be open channel flow: they are both examples of gravitational flow.

Methods Used to Measure Open Channel Flow

A variety of methods are used to measure flow in open channels. Many different factors help determine which method is best for a given application. These factors include the nature of the application, budget, accuracy needs, and reporting requirements. This section discusses different methods for measuring open channel flow.

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Jump to:

	Part 1 - Introduction
	Part 2 - Methods - Dilution, Timed Gravimetric, Weirs & Flumes
	Part 3 - Methods - Area/Velocity, New Developments
	Part 4 - Comparison Table

Jesse Yoder has fifteen years experience as an analyst and writer in process control. He specializes in flowmeters and other field devices, including level, pressure, and temperature products. He has written over 40 market research studies in industrial automation and process control.

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