The flooding is caused by the retreat of smaller glaciers near Mendenhall Glacier, a result of global warming that creates a basin filled with rain and melting snow each spring and summer. When the water pressure is strong enough, it can seep under or around the ice dams formed by Mendenhall Glacier and flow into Mendenhall Lake and eventually the Mendenhall River.
Since 2011, this phenomenon has also led to flooding of roads and homes near lakes and rivers. Last year’s floods engulfed large areas, causing riverbanks to collapse, homes to be flooded, and at least one house to be submerged in the swiftly moving waters.
Authorities indicated that the extent of this week’s flooding was unprecedented, leaving residents distressed as they attempted to salvage furniture, books, and other possessions in the midst of warm, sunny weather. Debris such as garbage bags, wood, boxes, wet insulation, carpets, and other items were stacked along road curbs on Wednesday. Street sweepers were busy clearing the muddy aftermath left by the receded water.
Eran Hood, an environmental science professor at the University of Alaska Southeast who has spent years studying Mendenhall Glacier, mentioned that while the basin was created by glacier retreat, climate change has minimal impact on the annual fluctuations in flood levels in Juneau.
He expressed, “It’s evident that these floods will persist over several decades, but predicting the size of future floods is challenging without more precise glacier dynamics modeling, due to numerous factors that influence their magnitude.”
Hood mentioned that at some point, Mendenhall Glacier will shrink and become too thin to act as a barrier.
The flooding serves as a stark reminder of the global hazards posed by failures of snow and ice dams, a concept known as jokulhlaup, which is relatively unfamiliar in the United States. Threatening approximately 15 million people around the world.
Juneau, a city with about 30,000 inhabitants in southeast Alaska, can only be accessed by plane or boat. Despite peak tourist season, the city is currently facing a housing shortage that could limit temporary accommodations for flood victims. Rental car options in Juneau are also limited for those whose vehicles were affected by the flooding.
Authorities reported that the Mendenhall River hit a new record high of 15.99 feet (4.9 meters), approximately a foot higher than last year’s floods, and the water extended further into Mendenhall Canyon. Some homes beyond flood-prone areas were reached by the water, and the canyon is situated about a 15-20 minute drive from downtown Juneau.
Alyssa Fisher shared that she didn’t anticipate flooding in her area when she went to bed on Monday night. However, her father woke her up over FaceTime a few hours later to inform her of rising water levels outside. She moved his car to higher ground, grabbed essential items, and relocated to a local school shelter with her two children, ages 4 and 8, along with their pets. She noticed that the truck’s license plate had been bent by the floodwaters.
Source: www.nbcnews.com
