Home North pole ice Engineers measure snowpack to predict flooding

Engineers measure snowpack to predict flooding

0

As you have heard, a flood advisory is now in effect until this (Monday) morning for the Chena River near the North Pole and upstream of its headwaters. There is also a flood watch on the Salcha River.

The river level on Upper Chena rose gradually over the weekend, and the National Weather Service reports minor flooding in low-lying or flood-prone areas, including along the Chena Hot Springs Road and area. from Steamboat Landing to the North Pole. The latest river forecasts are at weather.gov/aprfc.

The U.S. Army Corps of Engineers – Alaska District regulates flow on the Chena by operating the Moose Creek Dam as part of the Chena River Lakes Flood Control Project at the North Pole.

USACE, in partnership with the U.S. Department of Agriculture’s Natural Resources Conservation Service, uses snow survey data to predict potential flooding during ice breakup, collecting data from nine monitoring in the Chena River Basin. This is how they estimate the volume of water when the snowpack melts in the mountains…to anticipate when to close the dam gates and prevent flooding downstream in Fairbanks.

Lauren Olivier

/

USACE – District of Alaska

The Chena River meanders through downtown Fairbanks at dusk on April 30, 2022.

After the 1967 Fairbanks flood that caused approximately $80 million in damage, the Chena Project was built in the 1970s to protect the city, the North Pole, and Fort Wainwright from future disasters.

Although the floodplain behind the dam remains dry for most of the year, USACE officials may retain water when river levels are high due to heavy snowmelt, ice jams or heavy rains. Since its construction, the 7½ mile earth dam has operated 30 times.

Rosie Duncan, a USACE employee who helped with the snow survey work, says the Fairbanks area is still feeling the effects of December’s record snowfall and freezing rain event.

Chena River Basin

An aerial image of the Chena River Basin near Pleasant Valley and Munson Ridge on March 30, 2022.

Nathan Epps, head of the hydraulics and hydrology section, says that “snow records measured approximately double the normal snow-water equivalent in the Chena watershed, which is the highest recorded since the beginning of measurements in 1980”.

During normal operations, the Moose Creek Dam regulates the flow of the Chena River to no more than 12,000 cubic feet per second through downtown Fairbanks.

The effects of flooding downstream along the river also depend on conditions in the Tanana and Little Chena rivers as well as local drainages. Low-lying areas near the Chena River may experience minor flooding, while elevated groundwater may occur for several thousand feet downstream of the dam.

Mega project

Meanwhile, construction will begin this spring to strengthen the structure. Dubbed a “mega project” and funded by the recently enacted Infrastructure Investment and Jobs Act, the Bauer Foundation Corp. of Florida was awarded a $75.5 million contract to establish an on-site mixed concrete barrier wall at the base of the dam that spans 6,200 linear feet at depths of up to 65 feet.

The project stems from a 2017 modification study that recommended strengthening the dam to extend its life and improve the protection of the greater Fairbanks area for many years to come. Construction is expected to be complete by January 2026. The dam will continue to operate and regulate the flow of the Chena River as needed while work is underway.

“The successful completion of this modification project will allow us to address the risks associated with aging infrastructure and deliver an upgraded infrastructure that is built to last,” DeRocchi said.

The public is encouraged to stay informed of weather and flooding conditions by monitoring news reports and social media posts. It is also recommended that people remove their belongings from low areas, such as basements and crawl spaces, to protect these items from potential flood damage.

As the USACE prepares for a busy spring that may involve the operation of the Moose Creek Dam to reduce flood risk and make safety improvements to the structure itself, local citizens can rest assured that the team has their best interest in mind.

“Public safety is always our top priority,” DeRocchi said.