One of Alaska's most populated cities is bracing for potentially catastrophic flooding as a basin dammed within the Mendenhall Glacier has started to release water.

For the third consecutive year, a wave of water gushed out of an Alaskan glacial lake, threatening the state’s capital city of Juneau. But, flood barriers installed by the city managed to prevent disaster from unfolding in the picturesque port town despite record-breaking water levels this week.

A huge basin of rainwater and snowmelt dammed by Alaska’s Mendenhall Glacier has started to release, sending a potentially record surge of flooding toward parts of Juneau in what has become an annual concern for residents A huge basin of rainwater and ...