Houses, Trees Swept Away in Alaskan 'Jökuhlaup' Flood

Alaska’s capital city of Juneau is reeling from a flood over the weekend. The flooding swept away two homes on the Mendenhall River. It also forced the city to shut down eight other structures. The flood was caused by a glacier dam break.

Glacier dams occur naturally. They're formed by ice that blocks river flow in a valley. Lakes form behind the dams. Falling rain, snow, runoff, and snowmelt help the lake to grow. Sometimes a glacier dam bursts. That can cause a jökuhlaup. The word is Finnish. It means a rapid burst of water caused by a shift or fracture in a glacier.

Scientists say melting glaciers around the world put 15 million people at risk. While climate change is clearly melting the Mendenhall Glacier and others, it is not clear what caused the weekend flood, environmental scientists say.

The jökuhlaup that occurred Saturday broke records. It pushed the Mendenhall to a height of nearly 15 feet, three feet higher than the 2016 record. Sensors installed to monitor glacial outbursts were washed away by the rapidly rising floodwaters.

“We sat down there and were just watching (the flood), and all of a sudden trees started to fall in,” resident Amanda Arra told the Juneau Empire. “And that’s when I started to get concerned. Tree after tree after tree, and then (my neighbor’s) house started to go — the porch fell off.”

The river stole 50 feet of Arra’s backyard. It left a portion of her home hanging dangerously over the waterway. 

Authorities on Tuesday continued to warn residents not to go near the river because its banks are unstable even though the floodwaters have receded.

Photo from Reuters.

Reflect: What are some ways that weather and nature can impact our communities? How can we work together to prepare for and respond to these changes?