Stream gauging is a technique used to measure the level and flow of water in streams. Stream gauging is an important tactic for understanding the ecological composition of a given area, and stream gauges can be used to collect data about environmental growth and development. In order to successfully gauge a stream, you’ll need to measure the height (or stage) of the water at various locations across the surface as well as the velocity of water discharged from the stream.
A stream gauge is an instrument used to measure the height of the water level in a stream. Below, you’ll learn the ins and outs of using a stream gauge to assist in the stream-gauging process. Throughout the tutorial, we’ll also take a tour through some of the different equipment options that will help you get the job done. Let’s go!
Measuring Height
In order to gauge effectively changes in a stream over time, you should take measurements at regular intervals throughout the course of a year. To accomplish this, you can install a permanent stream gauge or use a temporary gauge. A drawback of temporary gauges is that you’ll need to make sure you choose (and stick to) a consistent location throughout the series of measurements you’ll be taking.
The SECO 99000 Stream Gauge from Engineer Supply features a four-foot height and four-inch width and is ideal for permanent installation, allowing you to read water levels instantly. Sturdy fiberglass construction in SECO’s stream gauges ensures a long lifespan and resistance to wear from the elements. If you’re dealing with a stream deeper than four feet, Crain offers gauges in four different sizes, the highest of which goes up to 16 feet.
Measuring Velocity
Once you’ve taken measurements of the height of a stream, you can use the data to calculate the find the velocity of the stream. Then, once you’ve determined height and velocity, you can determine the total discharge. But first things first!
To measure current velocity, you will need to use a current meter in addition to your stream gauge. Current meters have either a propeller or a wheel with small, open cones attached. You can measure the velocity of the water by counting the rotations of the wheel or the measuring the water contained in the cone-shaped cups. To account for environmental factors like friction and get the most accurate reading of a current’s true velocity, it’s best to measure at 0.6 times the depth of the stream.
Stream velocity varies not only at different depths, but also at different locations in the cross-section of the stream. The banks of streams have increased friction, which can throw off your velocity readings. Streams channels are neither perfectly straight or perfectly flat, so make sure to take measurements at various points along the stream to avoid skewing your results. Areas containing many plants or rocks should also be avoided as measurement locations.
Making Your Calculations
After measuring various sections of your stream, you’ll have the data needed to make your calculations. To calculate the discharge of each area of your stream multiply the area (width x height) of your stream section by the velocity. It’s a simple calculation that results from a somewhat tricky measuring process, but stream gauging can be made easy with the help of Engineer Supply. Check out our full selection of stream gauges for reliable support you can depend on every time!