The flooding occurs as a result of a smaller glacier close to Mendenhall Glacier had retreated — a casualty of the warming local weather — and left a basin that fills with rainwater and snowmelt every spring and summer time. When the water creates sufficient stress, it forces its manner below or across the ice dam created by the Mendenhall Glacier and enters Mendenhall Lake and finally the Mendenhall River, because it did this week.
Since 2011, the phenomenon has at instances flooded streets or properties close to the lake and river, and last year floodwaters devoured large chunks of the riverbank, inundated properties and despatched at the very least one residence crashing into the raging river.
However the extent of this week’s flooding was unprecedented, officers stated, and left residents shaken as they tried to dry out furnishings, books and different belongings throughout a stretch of heat, sunny climate. On Wednesday, piles of rubbish baggage and different objects — wooden, containers, sodden insulation and carpeting — dotted the curbs. A road sweeper was tackling the grey, silty grime the retreating waters had left behind.
Whereas the basin was created by glacial retreat, local weather change performs nearly no function within the the year-to-year variations within the quantity of the flooding in Juneau, stated Eran Hood, a professor of environmental science on the College of Alaska Southeast who has studied the Mendenhall Glacier for years.
“It’s very clear that these floods will persist for some period of time, once more, on a type of decadal timescale into the longer term,” he stated. “However there are such a lot of totally different competing elements that work to both improve the amount of the flood or lower the amount of the flood that we’d like to have the ability to quantify that it’s tough to say how massive floods shall be sooner or later with out rather more detailed modeling of the glacier dynamics.”
In some unspecified time in the future, Mendenhall Glacier will retreat and skinny sufficient that it might probably now not act as a dam, Hood stated.
The flooding is a reminder of the worldwide danger from bursting snow-and-ice dams — a phenomenon referred to as a jökulhlaup, which is little recognized within the U.S. however might threaten about 15 million people around the globe.
Juneau, a metropolis of about 30,000 individuals in southeast Alaska, is reachable solely by aircraft or boat. It’s the peak of the vacationer season, and the town is already scuffling with a housing scarcity that might restrict non permanent lodging out there for flood victims that may want them. Juneau additionally has restricted rental automotive companies for these whose autos had been swamped.
The Mendenhall River crested at 15.99 ft (4.9 meters), a brand new document, topping the extent throughout final yr’s flood by a couple of foot, and the water reached farther into the Mendenhall Valley, officers stated. The town stated the water reached some properties exterior anticipated flood areas. The valley is roughly a 15 to twenty minute drive from downtown Juneau.
Alyssa Fischer stated that when she went to sleep Monday night time, she didn’t suppose she needed to fear about flooding the place she lives. Her dad woke her up hours later through FaceTime and alerted her to rising water exterior. She helped him transfer his automobiles to greater floor, in addition to her quails, earlier than evacuating along with her 4- and 8-year-old kids and pets to a shelter at a neighborhood faculty. She stated she seen the license plate on her truck was bent from the water present.
