Community Ag Alliance: Irrigation season may be early this year
February 15, 2018
Dry condition and mild temperatures continue to hamper snowpack.
The Natural Resources Conservation Service, who collect and report snowpack information through their system of Snotel, or Snow Telemetry, sites, is currently reporting the snowpack in the Yampa/White River Basin at 73 percent of average.
By comparison, the highest reported snowpack in the state right now is the South Platte River Basin at 92 percent of average, and the lowest is the Upper Rio Grande Basin, which is listed at 33 percent of average.
Snowpack reports, by state and drainage basin, can be viewed at wcc.sc.egov.usda.gov/reports/SelectUpdateReport.html.
Given our current conditions, it's possible that water could be in short supply for some irrigators in Northwest Colorado.
With that in mind, if your irrigation delivery ditch doesn't already have a measuring device on it, or if the device is not working properly due to damage or wear, it's probably a good idea to replace or put a new one in.
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While there are many types and styles of measuring devices available, Parshall Flumes are probably the most popular here in Northwest Colorado. If made of steel or sheet metal, they are usually constructed in a shop, then transported to the site for installation. A skilled fabricator can cut and weld together a metal Parshall Flume in a short amount of time. They can also be made of reinforced concrete, which may have a longer lifespan but require more construction time and have to be built on-site.
The Parshall flume was invented by Ralph L. Parshall in 1921. Parshall, an internationally known professor at Colorado Agricultural College — now Colorado State University — noticed that many types of water measurement were not accurate and so, came up with the flume that now bears his name.
Parshall Flumes require that a chart, specific to its throat width, be used to convert the gage reading to a flow rate. The throat is the center section of the flume that is always narrower than the inlet and outlet sections.
Water in closed pipelines, with full pipe flow, can be measured with a properly installed flow meter. Older flow meters used a propeller or venturi tube inside the pipe. While effective, these do create a small obstruction in the pipe. They also have moving parts that wear over time.
There are now sonic flow meters available, that when installed correctly, are very accurate, durable and have very few moving parts to wear out. Sonic meters require electric power, but power can be provided with batteries, which can be recharged with a solar panel.
Always check with your water commissioner or your local Colorado Division of Water Resources Office before replacing or installing any type of water measurement. Make sure the device you plan to install is approved for use and that you know how to install it correctly.
Vance Fulton is an engineering technician with the Natural Resources Conservation Service, and can be contacted at 970-879-3225, ext. 106 or firstname.lastname@example.org.