7 / 2023-12-04 22:43:19

Impact of water-induced hazards in the Asian Highland

Water-induced hazards, Asian highland, cascading hazards, debris flow

The Asian Highland is one of the most seismically active mountain belts in the world with several kilometers of relief and very prone to catastrophic mass failure. High grade of rock weathering and subsequent torrential rainfall are directly related to the increase in the numerous geo-hazard problems i.e., landslides, debris flow, floods, etc.  The coupling effect of seismo-tectonic activities and Asian rainfall is triggering numerous water-induced hazards. Recent events such as Seti Flood (2012), Chamoli Flood (2021), Melamchi debris flow (2021) and Lhonak lake burst (2023) have shown the scale of devastation in this region. The Seti Flood was created due to a large rock slope failure at Sabque Crique, Annapurna range, Nepal. The collapsed material transported the whole material deposited in upstream of the Seti River creating large-scale debris flow. More than 70 people lost their lives and many infrastructures were collapsed. Similarly, the catastrophic debris flow at Melamchi Bazaar killed at least 5 people and damaged major infrastructures including the Melamchi Water Supply Project. This debris flow caused widespread aggradation along tens of kilometers of Melamchi River corridor, with up to 15 meters of deposition in the town of Melamchi Bazaar. The source of these deposits lies in the upper catchment of the Melamchi River at an elevation of ~3600m, where ~ 100 million m^{3 of} sediments was stored behind a paleo-landslide dam. These cascading events highlight the importance of understanding paleo-landslide dams, glacial moraine, or other geomorphic process in the mountain catchment. This is because most of the human settlements lie within large-scale landslides and river corridors. Therefore, it is of utmost necessity to map and locate geomorphic and tectonic features to understand the potential hazards in the mountain ecosystem.