Glacier-dammed lakes in Alaska

Glacier dam lakes are hydrologic features that occur only in cold and wet environments that are conducive to glacial formation. Some of these lakes are created when a glacier encroaches on a tributary drainage and blocks the outlet. Runoff then starts to collect above the encroachment until a breach begins to form in the glacial ice and then the water is suddenly released. These jokulhlaup events occur repeatedly at locations where topography and climate permit. Typically the frequency of releases is about once a year. At some locations the subsequent wave released will achieve discharge rates that exceed the median annual maximum and cause flooding. This paper explores the factors necessary for glacier lake formation and the processes responsible for causing a glacier dam to release its water. A survey is also made of the locations where major jokulhlaup events are known to have occurred in the state of Alaska.