Debris flows originating in the mountain cryosphere under a changing climate: A review

Abstract

Debris flows originating in the mountain cryosphere (DFMC) are one of the most globally important, widely distributed mass flows (and natural geohazards) in mountain areas with a high altitude and/or high latitude. This is particularly the case in high mountain areas that have been undergoing rapid glacier retreat, permafrost degradation, and other melt/thaw related processes. As a consequence, the actual hazards and potential risks of DFMC have drawn increasing attention in the context of global climate change (i.e. a rising temperature and higher occurrence of strong precipitation events). Unlike debris flows at low elevations, where their occurrence is closely related to precipitation (intensity and duration), the breach of a DFMC event depends on precipitation and/or air temperature, which in turn influence melt/thaw processes, rending the formation mechanism much more complicated. Although research has been widely carried out on DFMC in past decades, there is still a long way to go before we have reached a complete understanding of the formation mechanism and triggering conditions. This review summarizes recent progress in the study of DFMC, including typical DFMC events and their causes, the failure mechanisms of rock (or ice-rock joints), the characteristics of moraine deposits, initiation through hydraulic erosion (entrainment), the relationship between DFMC initiation and meteorological conditions, and the slope stability of the mountain cryosphere under a changing climate. Several issues that should be addressed in future research are also discussed.

High Mountain Asia hydropower systems threatened by climate-driven landscape instability

“…Loose sediment exposed by glacial retreat or deposited by landslides can be remobilized during heavy rainfall or by further slope failures and evolve into debris flows [57][58][59] (Fig. S1).…”

“…S1). The 2010 debris flows in Tianmo Valley, Tibet were attributed to heavy rainfall and meltwater in a periglacial environment where frequent landslides increased sediment availability 57,60 . Precipitation is projected to increase in HMA associated with more rainstorms that may exacerbate slope instability 5 .…”

Mass-Movements in Cold and Polar Climates

“…Debris flows are rapid, downslope flows of poorly sorted debris mixed with water (e.g., Iverson, 1997), and are common on the slopes of periglacial environments, including in the European Alps to Iceland (Figure 6), from the Tibetan Plateau to Antarctica (Decaulne and Saemundsson, 2006b;Morino et al 2019;Cannone et al, 2006;Oliva and Ruiz-Fernández, 2015;Sattler et al, 2011;Yu et al, 2020). Debris flows can travel over long distances and transport large amounts of material at great speed (Zimmermann and Haeberli, 1992).…”

Alluvial fan of Glazne river, Bansko town, SW Bulgaria

“…Трансферът на кластичен материал към локалните депоцентрове в речните долини се захранва от редица гравитачни процеси: лавини, срутища, свлачища, дебритни потоци и др. (Cossart et al, 2013;Yu et al, 2020). Протичането на тези процеси е неизбежно -то се контролира от нестабилността на вертикализираните долинни склонове, новогенерираната напуканост (neo-joints, Cossart et al, 2013), присъствието на обилен неспоен моренен материал и периглациални блокажи, а в някои случаи (приложимо за Пирин) -те са стимулирани от сеизмични събития.…”