Ecological Indicators (Oct 2024)
Risk assessment of glacial debris flow on highway under warming climate: A case study of Tianmo Gully in the southeastern Tibetan Plateau
Abstract
In the context of a warming climate, glacial debris flows will inevitably increase under the coupled effect of increased temperature and precipitation. However, the extent of future losses is unclear due to the complexity of modelling glacial debris flow processes. This study integrated the degree-day model, the TRIGRS model, and the LS-RAPID model to assess increasing risk in the future period (2071–2100) under the SSP2-4.5 scenario compared to the present. A fatal glacial debris flow in the Tianmo Gully that occurred on September 4, 2007 (hereafter referred to as “the event”) was taken as an example. By the 2090s, compared to the event, the contribution of temperature to the occurrence of glacial debris flows was projected to increase significantly, from 77.05 % to 89.68 % under the SSP2-4.5 scenario. Combining meltwater and precipitation, the study reproduced the propagation of the event and simulated the future extreme debris flow event. Although the section of National Highway 318 (G318) below Tianmo Gully was relocated and reconstructed 150 m away from the historic sedimentary fan, a section of 88.46 m remained at risk of inundation in the future. The maximum height of the debris flow dam in the Parlung Zangbo River could reach up to 34.50 m, doubling the height of the event. Debris removal from the road is estimated to take 1 day, resulting in a projected loss of tourism revenue amounting to RMB 17.82 million. Without relocation, the clearing time would take up to 3 days. The economic benefit of rerouting the section was projected at RMB 13.81 million. The mechanisms of glacial debris flow in Parlung region are similar. Both the concept of model integration and the comparison of the simulation results are of great importance for risk assessments under global warming.
