Geomorphic Process Chains in High‐Mountain Regions—A Review and Classification Approach for Natural Hazards Assessment

Abstract

Populations and infrastructure in high mountain regions are exposed to a wide range of natural hazards, the frequency, magnitude, and location of which are extremely sensitive to climate change. In cases where several hazards can occur simultaneously or where the occurrence of one event will change the disposition of another, assessments need to account for complex process chains. While process chains are widely recognized as a major threat, no systematic analysis has hitherto been undertaken. We therefore establish new understanding on the factors that directly trigger or alter the disposition for subsequent events in the chain and derive a novel classification scheme and parameters to aid natural hazard assessment. Process chains in high mountains are commonly associated with glacier retreat or permafrost degradation. Regional differences exist in the nature and rate of sequencing—some process chains are almost instantaneous, while other linkages are delayed. Process chains involving rapid sequences are difficult to predict, and impacts are often devastating. We demonstrate that process chains are triggered most frequently by progressive failures, being the result of gradual landscape weakening and not due to the occurrence of a distinct process. If fluvial processes are part of the process chain the reach (or mobility) of process chains is increased. Increased mobility can also occur if sediment deposition areas along river channels are activated. As climate changes causes glacial environments to transform into sediment‐rich paraglacial and fluvial landscapes, it is expected that the mobility of process chains will increase in the future.

Glacier Retreat in Eastern Himalaya Drives Catastrophic Glacier Hazard Chain

“…Sedongpu CGHC is a geomorphic process chain (Mani et al., 2023), different from ordinary landslides or debris flows (Gnyawali et al., 2020). Initially, a rock‐ice avalanche occurred at an altitude of 6,200 m when the hanging glacier failed.…”

Causal mechanisms and evolution processes of “block-burst” debris flow hazard chains in mountainous urban areas: a case study of Meilong gully in Danba county, Sichuan Province, China

“…However, these studies have not revealed the entire process and mechanism of the formation, development, evolution, and hazard-causing of the MLG debris flow hazard chain under the internal and external dynamic coupling. Unlike the simple superposition of single or multiple hazards, the mountain hazard chains often have temporal and spatial continuity and extension, and exhibit cascading and compound effects, often characterized by huge damage, wide impact range, and long duration (Chen and Cui, 2017;Mani et al, 2023). With the acceleration of economic development and population growth, engineering activities in mountainous urban areas in western Sichuan are also increasing rapidly (Wang et al, 2018).…”

Identification and Analysis of the Geohazards Located in an Alpine Valley Based on Multi-Source Remote Sensing Data

“…Situated in the collision zone between the Eurasian Plate and the Indian Ocean Plate, the Hengduan and the Himalayan Mountains possess a complex geological environment with active geological movements, resulting in numerous types of geohazards and cascading geohazards. Among them, cascading processes triggered by landslides and rockfalls are the most typical in the region [2][3][4], such as the "landslide-debris flow-river blockage" 2 of 18 cascade in Sindupalchowk, Nepal, in 2014 [5]; the "landslide-debris flow-dammed lakebreach flood" cascade in Tibet, China, in 2018 [6]; and the "earthquake-landslide/rockfalldammed lake-flood" cascade in Kukrekhola, Nepal, in 2018 [7]. In the Latudi River valley, a tributary of the Nujiang River in the Hengduan Mountains, the geological environment is fragile.…”