Flumes can be applied to a variety of different flow channel conditions, but one of the most common applications is for irrigation. Water commissioners, water rights consultants and more make use of flumes to measure flow rate. Unfortunately, there are several problems that can arise during the process that you should be aware of. Learn all about the most common irrigation flume problems.
Misplaced Staff Gauge
A staff gauge is a way flow rate can be measured by marking where the water level is in a flume. Problems arise when the staff gauge isn’t placed at the right point. Remember, it should always be located behind the throat, approximately two-thirds of the converging wall’s length away. Placing it upstream, at the entrance or directly in the throat won’t provide the accurate measurements you need.
Flow Taking Over the Flume
In order for a flume to work properly, the flow must pass through it directly in its entirety. There are two ways in which this can be violated. The first is when the flow manages to go around the flume. This typically occurs when the walls or floor of the flume erode to the point where wastewater can find new passages. Additionally, the flume can become completely submerged. This occurs when the flow out of the flume is restricted, causing the water to back up and eventually overtake the flume itself.
Poor Velocity Profile
Flow rate measurement is only accurate if the flow can reach a state of criticality as it passes through the flume. Anything less or more than a critical state will lead to inaccurate measurements. That’s why it’s so important to optimize upstream approach conditions. They must be at a subcritical level in order to reach criticality within the flume. Additionally, the flow needs to approach with an even velocity profile. Any bumps or sudden turns can create uneven flow surfaces and additional turbulence.
Dirt and Debris
An irrigation flume will naturally acquire debris over time. Flumes are generally self-cleaning, especially compared with weirs, but you’ll still need to do some maintenance every now and then to ensure that they’re operating properly. Algal growth can be a particularly troublesome issue, as it can change the dimensions of the flume. When you do clean, you’ll need to keep an eye out for any kind of debris that will change the interior dimensions of the flume.
Over time, an irrigation flume’s shape may become distorted. This can happen both during installation and long after, so the flume needs to be properly braced. Bracing a flume is known as cribbing, and it helps prevent the walls from bending or falling in any direction. Remember, if the interior of the flume changes, all measurements it takes will be thrown off.
Irrigation Flumes From Tracom
If you’re looking to avoid the most common irrigation flume problems, Tracom is happy to help. We can help you craft a long-lasting fiberglass flume suited for your flow channel conditions and ensure that installation goes smoothly. Contact us today to get started!