Rockfall susceptibility along Pasang Lhamu and Galchhi-Rasuwagadhi highways, Rasuwa, Central Nepal

摘要

The road network in Central Nepal suffered blockades and damage from numerous landslides and rockfalls due to the earthquakesequence in Gorkha, Nepal, in 2015. Additionally, frequent rainstorms in the area contributed to the recurrence ofrockfalls and other types of landslides, hindering road infrastructure development and environmental management. Despitethe several existing regional and local studies on landslide susceptibility in the area, rockfall-specific analysis is still lacking.In this paper, we assessed rockfall susceptibility in the sections of the Pasang Lhamu highway and the Galchhi-Rasuwagadhihighway in the Rasuwa district using a physically based model. We generated three-dimensional rockfall trajectories alongthe roads and used them to infer the rockfall susceptibility of the area. We selected potential locations for the initiation ofrockfalls based on the optimization of the gridded slope angle, relief, and terrain ruggedness, validated the source map usingstatistical parameters, and compared them with a field-mapped rockfall source inventory. As a result, we identified which roadsections in Ramche, Dandagaun, and Syaprubesi are highly susceptible to rockfalls. We published the field-based inventoryof rockfall sources and segment-wise rockfall susceptibility of highways, where a rockfall susceptibility index of 5 indicatedvery high susceptibility and 1 very low susceptibility. Such findings and maps are helpful for researchers, land planners,developers, government bodies working on disaster risk reduction, and policymakers to design a preliminary framework forrockfall mitigation and sustainable roads.