Purchase photos

Gauging rivers

3/31/2013

By MIKE CORN

mcorn@dailynews.net

SCHOENCHEN -- In the normally arid stretches of northwest Kansas, often there's little need to worry about how much water is flowing down a river.

But when Hays and Russell -- or perhaps Mother Nature dictate it -- accuracy is paramount.

That's when the U.S. Geological Survey's Hays-based gaging team goes into action.

They use a mix of modern technology built on a tried-and-true method developed more than 100 years ago.

But it still takes a trained observer to know right where to measure to get an accurate reading of the amount of water flowing.

Not at all unlike the water flowing down the river, measuring -- especially with automated systems that dot the region -- it's a moving target that must be adjusted as beaver dams are built and then collapse. Or perhaps when cattails either grow up and slow the flow or wash away.

Nathan Sullivan and Craig Dare, in charge of the Hays USGS office, are quick to correct any mistakes the automatic systems might make.

When Hays called for the release of water from Cedar Bluff Reservoir to augment its supply along the Smoky Hill River near Schoenchen, Dare and his crew actively were watching gauges.

It just happened two gauges were giving incorrect readings on the same day.

The gauge at Cedar Bluff Reservoir was easy enough to diagnose, as the device itself malfunctioned and had to be swapped out with a new unit.

The river flow downstream of Schoenchen had to be re-measured so adjustments could be made.

In some cases, those adjustments can be dramatic, including the near doubling of flow downstream of Schoenchen.

Much of the discrepancies can be blamed on the intermittent nature of streams.

"The last time we had flow here, which was a couple years ago, we had beaver dams," Dare said.

As the river dried out, the beaver dams were abandoned and the water -- once it returned -- washed them out.

Knowing the interest in the river levels, Dare knew it was time to measure the river upstream of Schoenchen.

The math behind river flow is relatively simple, as it's a matter of the width of the stream times the depth times the velocity of the water.

"We report everything in cubic feet per second," Dare said.

There's 7.5 gallons in a cubic foot of water.

Walking the river's edge, Dare and Sullivan sought to find a spot that reflected actual flow. They didn't want areas where the stream spread, slowing the flow, or where there were obstructions to perhaps speed the flow.

Sullivan took to the water, despite its 40-degree reading, to find just the spot.

Satisfied, he strung a cord across the channel and started taking readings.

He took dozens, using an acoustic electronic device that effectively uses a Doppler system not at all unlike that of a Doppler radar used by the National Weather Service.

His on-site readings showed the flow curve needed to be adjusted.

"It's an ongoing thing," Dare said. "These rivers change all the time."

With approximately 70 river gaging stations under the watchful eye of the Hays USGS office, each one gets visited nearly every six weeks -- sooner if there's water flowing in them.

"Something like this special," Dare said of the reservoir's release, "we'll come out now."

Gauges are located on the Arkansas, Smoky, Solomon and Saline rivers, as well as Big Creek.

On the Smoky alone, there's gauges at Elkader south of Oakley, Arnold in Trego County, two upstream and downstream of Schoenchen, near Pfeifer, south of Russell and near Ellsworth.

"All because somebody wants to know," Dare said of the reasons for the gauges.

* Real-time streamflow data are available online at waterdata.usgs.gov/ks/nwis/rt.