GLOF

Glacial Lake Outburst Flood (GLOF) is a sudden release of water from a glacial lake when the dam formed by ice and moraine materials fails. Such outbursts can discharge large volumes rapidly, producing floods that carry ice, rocks, and sediment downstream and may travel long distances.

Most glacial lakes are dammed by moraines or by remnants of ice left behind by retreating glaciers. The dam can breach through overtopping and erosion as inflow grows, through structural failure of the moraine, or by ice calving into the lake. Triggers include warm spells, heavy rainfall, rapid snowmelt, earthquakes, and landslides that destabilize the dam.

GLOFs generate fast-moving floods that scour channels and deposit large debris, threatening villages, roads, hydroelectric facilities, bridges, and agricultural land. Secondary hazards in downstream valleys include landslides and debris flows.

Mitigation and monitoring rely on early warning systems, remote sensing, and field surveys to track lake levels and dam stability. Engineering options include controlled drainage to lower lake volume, strengthening or rebuilding moraines, constructing drainage channels, and land-use planning to reduce exposure.

GLOFs are linked to climate change, which drives glacier retreat and destabilizes lake dams. They occur globally but are most common in high-mountain regions such as the Himalayas, the Andes, and the Alps. Notable events include the Dig Tsho GLOF in Nepal in 1985.