Landscape impacts of catastrophic glacier detachments

Glacier detachment is a recently discovered type of glacier instability in which large parts of a glacier fail catastrophically. The detached glacier ice, in combination with mobilised lithic material, may lead to mudflows further down the valley, leaving a trail of devastation in its wake. Due to the novelty of this high mountain hazard, its medium- and long-term effects on the landscape have been little studied. In this thesis, I address this research gap by analysing the medium-term impacts of glacier detachments in the Degilmoni Poyon and Shuraki Kapali catchments in central Tajikistan using remote sensing imagery. Between 2016 and 2023, four out of five glaciers in the Degilmoni Poyon and Shuraki Kapali catchments affected by glacier detachments rapidly regained volume, despite above average warm and dry climatic conditions. Consequently, the exposed glacier beds were re-covered by ice within a few years, providing protection against erosion. Just as quickly as the glaciers recovered after the detachments, their deposits in the runout zones vanished. In the Degilmoni Poyon catchment, the deposited ice melted within just three years. Five years after the detachment, only missing patches of vegetation and striations in a few areas of the runout zone indicate that a detachment has occurred. Glacier detachments also pose a significant risk to communities, as can be seen in the Shuraki Kapali catchment. In both 2016 and 2017, glacier detachments triggered mudflows and flooding in inhabited areas, damaging infrastructure and destroying farmland. Although the affected area has since been avoided for new development, a new settlement has been built in its immediate vicinity. This is a cause for concern, as the new findings suggest that glacier detachments could also occur there in the future. The findings of this study highlight the transience of the traces left by glacier detachments in the landscape. However, the fact that the traces left by a detachment disappear relatively quickly should not obscure the reality that glacier detachments pose an immediate threat to villages located in their runout zones.