Temps kick breakup into action

Posted: Monday, April 12, 2004

The Kenai River is not in imminent danger of flooding from snowmelt. In fact, all signs point to a normal, uneventful breakup.

That may not be the conclusion the average person might reach when they learn that snowpack in some places along the Kenai River is close to twice the normal amount for this time of year.

The extra snow, however, is at too low an elevation to cause any problems.

Most of the runoff contributed to the Kenai from snowmelt comes from high in the Kenai Mountains, where the snowpack is about average, according to Ben Balk with the Alaska Pacific Region River Forecast Center, a division of the National Weather Service.

"Although the lower elevation snowpack is above average for this time of year, the higher elevation in more normal," Balk said. "This year it looks like the mountains are running around 90 to 110 percent or so."

Because so little of the snow at lower elevations contributes to the total runoff from snowmelt, the extra water won't raise the Kenai's level significantly.

"The river can handle that (low elevation) 150 to 200 percent snowpack," Balk said.

What can cause high water levels and potential flooding of the Kenai is a cool April and May which means snowpack in the mountains will likely be above average followed by a hot and sunny June which means a lot of water from snowmelt pouring into the river over a short period of time.

A sudden change from a cold spring to a hot summer is rare, however.

"The Kenai River doesn't typically have any snowmelt flooding issues," Balk said.

That's not the case for other channels on the peninsula, like the Anchor River.

The Anchor is primarily fed by the Caribou Hills. Relatively low elevation means the snow on the hills can melt earlier and quicker than snow in the mountains, which can lead to flooding.

"The Anchor River is a little more prone to snowmelt," Balk said. "It's one of the few places in Southcentral that has flooding issues."

Flooding of the Anchor was almost an issue last week. The National Weather Service issued an advisory Wednesday to residents in the Homer vicinity that the river had swollen due to rain and snowmelt, and ice in the river channel was constricting the flow and aiding the rise in the river's level.

The result was minor flooding along Kachemak Drive and East End Road.

"We also had informal third-party reporting of flooding in basements," said David Gibbs, emergency manager for the Kenai Peninsula Borough.

The flooding might have been worse, if not for the efforts put into clearing drainage ditches after the heavy rains in the fall of 2002.

"The ditches seem to be working very well," Gibbs said. "There was a lot of effort given to clear the debris out of the ditches."

The flood potential of the Anchor River from snowmelt and ice jams currently is rated as average by the National Weather Service, but a change of weather could quickly in-crease that potential.

"A sudden warming spell with lots of high wind could create some problems," Gibbs said.

Rain also could create problems. As well as adding directly to the runoff, rain water warms snow and increases the rate at which it melts.

Despite the probability of a flood-free breakup this spring, there are no guarantees.

"To be able to predict floods, we'd have to be able to predict the weather," Gibbs said.



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