Brief communication: An approximately 50 Mm³ ice-rock avalanche on 22 March 2021 in the Sedongpu valley, southeastern Tibetan Plateau

Abstract

Abstract. On 22 March 2021, an approximately 50 Mm3 ice-rock avalanche occurred from 6500 m a.s.l. in the Sedongpu basin, southeastern Tibet. The avalanche transformed into a highly mobile mass flow which temporarily blocked the Yarlung Tsangpo river. The avalanche flow lasted ∼ 5 min and produced substantial geomorphological reworking. This event, and previous ones from the basin, occurred concurrently with, or shortly after, positive seasonal air temperature anomalies. The occurrence of future large mass flows from the basin cannot be ruled out, and their impacts must be carefully considered given implications for sustainable hydropower and associated socioeconomic development in the region.

Modeling Potential Glacial Lake Outburst Flood Process Chains and Effects From Artificial Lake‐Level Lowering at Gepang Gath Lake, Indian Himalaya

“…For instance, the Chamoli disaster total avalanche volume of ∼25 M m 3 containing 20% ice and 80% bedrock (failure depth up to 180 m) was released from a steep slope that caused huge devastation downstream (Shugar et al., 2021). Other events with even higher magnitudes have been reported in the recent past, for example, 10 7 M m 3 rock avalanche on Siachen glacier, in September 2010 (Berthier & Brun, 2019), the ∼50 M m 3 ice‐rock avalanche in the Sedongpu valley, in March 2021, Tibetan Plateau (Zhao et al., 2021), and the Kolka‐Karmadon rock/ice slide of September 2002 with a mass flow volume >100 M m 3 (Haeberli et al., 2004). Therefore, considering a range of avalanche scenarios (with varying volumes and ice‐rock ratios, see Table 1) enables us to comprehensively evaluate the potential hazard associated with the Gepang Gath Lake.…”

Intra‐Seasonal Variability in Sediment Provenance and Transport Processes in the Brahmaputra Basin

“…Earthquake and mass‐wasting events are common in the Namcha Barwa Gyala Peri region, with recent studies identifying landslides and glacier/landslide lake outburst floods as major processes of sediment generation (Wasson et al., 2022). The Sendongpu glacier on the western flank of Gyala Peri (Figure 11a) has experienced a series of glacier‐rock avalanches and debris flows over the past 7 years (Kääb & Girod, 2022; Kääb et al., 2021; Zhao et al., 2022). The most recent mass‐wasting event, which occurred on 22 March 2021, generated a massive volume of material, approximately 100 × 10 6 t (50 × 10 6 m 3 ) (Figure 11b, pre‐event and Figure 11c, post‐event).…”

Brief Communication: Rapid ~335 106 m3 bed erosion after detachment of the Sedongpu Glacier (Tibet)

“…Further rock-ice volumes of in total 100±5 10 6 m 3 were lost in the western flank of Gyala Peri, from the same area as the 50 10 6 m 3 rock-ice avalanche(s) of 2017, mentioned in Section 2. Of these roughly 100 10 6 m 3 , 50 10 6 m 3 failed over Jan 2020-Apr 2021 (mostly on 22 March 2021; Zhao et al (2022)) and another 50 10 6 m 3 during Apr 2021 -Nov 2022, all from the same area in the mountain flank (Fig. 1).…”