Glaciated high-mountain regions are particularly susceptible to climate change and associated changes in hazard situations. Glacier retreat is observed in most mountain regions of the world, which has given rise to the formation of numerous new glacial lakes. They are often located in remote and dynamic environments and – depending on the dam and lake type – may become unstable and prone to catastrophically burst out. Sporadic glacial lake outburst floods (GLOF) can evolve into highly mobile flows, which can pose a real threat in case they reach populated regions or infrastructure where they can cause inundation or massive deposition of sediment. Extreme flow events in high mountain regions can be caused by sources other than glacial lakes: Glacier-covered volcanos have, for instance, repeatedly caused severe disasters in the past. Through volcano-glacier interactions large amounts of water can be released and highly destructive flows (lahars) can form due to sediment entrainment. Highly dynamic and unsteady flow behavior of extreme flow events is typical, rendering risk assessments altogether a real challenge. The aim of this thesis therefore was to improve our understanding of the onset, propagation and potential impact of extreme flow events and to provide insights into complex processes and process chains. For this purpose field- and modeling based analysis of illustrative past and potential future events was carried out. Furthermore this thesis aimed at providing a compilation of existing and state-of-the-art modeling tools to simulate various types of extreme flow events.