Juneau getting better at responding to glacial flooding, emergency programs manager says

Agencies have made great strides in their ability to react and respond to glacial drainage events like last week’s flooding scare in the Mendenhall Valley, the city’s emergency programs manager told the Juneau Local Emergency Planning Committee at Bartlett Regional Hospital Wednesday.


Tom Mattice said he was impressed with how well the City and Borough of Juneau, U.S. Geological Survey, National Weather Service, University of Alaska Southeast and other organizations worked together to monitor the situation and keep the public informed.

“Everybody was in the loop, everybody played their part and I was happily amazed at how smoothly things went,” said Mattice.

Mattice said UAS researchers were able to take photographs from inside Suicide Basin, the basin to the side of the Mendenhall Glacier that filled with water — and then discharged it into Mendenhall Lake below — for two consecutive years. Those photographs, he said, led to accurate estimates that there was less water in the basin this year than there was last July, when the jökulhlaup, or glacial dammed outburst flood, caused minor to moderate flooding in parts of the Mendenhall Valley.

“We weren’t sure how much less water (was in Suicide Basin), but we were confident that it was going to be a less critical event than last year if the flow discharged the same,” Mattice said. “It could have come out faster, but we were pretty confident that it wasn’t going to be significantly worse than last year.”

Warning coordination meteorologist Joel Curtis, who is with the National Weather Service, said it is hard to determine the size of the opening through which glacially dammed water drains.

“There’s one huge unknown about these glacier dammed floods, and that is the size of the drainpipe that’s coming out of where the water is building up,” Curtis told the committee. “You just don’t know that. So if it’s bigger, you know, you could get a whole lot of water all at once, and then it will go down quicker. Or if it’s smaller, then the thing could persist for lots and lots of days.”

University researchers are planning to install monitoring equipment inside Suicide Basin Thursday, Mattice said. He and Curtis agreed those monitors will provide more precise, real-time information.

“I think that the lessons learned are really carrying forward into the future,” said Mattice. “We’re getting more information about how these events occur. We’re able to use the first event and this event to be able to tweak models and understand. Once we get sensors in the lake, we’ll be able to add that into the models to understand how much water’s going to be coming down. So the public information is going to get better, and we’re all going to do a better job going forward.”

The committee also discussed a recent Metropolitan Medical Response System exercise in Yakutat modeling how first responders would handle a shooting spree, as well as the committee’s plans for Emergency Preparedness Month, which is coming up in September.

Mattice suggested that each member of the committee bring one or two ideas about emergency preparedness for consideration at the committee’s next meeting on Aug. 8. That suggestion met with approval from Dan Garcia, the committee’s chairman.

“Each of us represents some … facet of this community,” said Garcia.

The meeting was quite well attended, as Mattice observed early in his remarks, with 16 people seated around the table and several others sitting at the back of the classroom in the Robert F. Valliant Center.

Garcia said after the meeting that the committee has been working to boost turnout and public interest, but he acknowledged last week’s flooding event may have spurred some extra attention.

“I think any near miss you have definitely triggers people’s interest in seeing where they personally sit, and where their organization sits if they’re part of a bigger group,” Garcia said. “We’re a planning committee, so obviously we don’t respond to things … (on an) emergency basis, but we plan for those future things.”

• Contact reporter Mark D. Miller at 523-2279 or at mark.d.miller@juneauempire.com.


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