Rock fall hazard and risk assessment along Araniko Highway, Central Nepal Himalaya

Rock falls are frequent along the steep slopes of highway cuts in mountainous areas like Nepal. Araniko Highway is a major highway connecting Nepal and China that has suffered from several instability problems. Recent earthquake activity in Nepal has generated many landslides, including rock falls along the highway, mostly between Lamosangu and Liping. These landslides have deposited huge piles of debris along the highway, as well as in the hill slope above, which has increased future risk of rock fall. Here, we have tried to analyze the distribution of rock falls along the highway, their mode of failure, and the associated hazard and risk. The analysis shows that most of the rock falls are concentrated along steep rock cliffs and are mostly rock topples, with some wedge and plane failure type. For the rock fall hazard and risk assessment of the highway, we have slightly modified the original rock fall hazard and risk assessment method to fit the condition of the Araniko Highway. The developed hazard and risk map effectively indicates various levels of rock fall hazard and risk along the highway. Based on the level of hazard and risk, the maintenance and inspection work can be carried out. In addition, the study reveals that this system can be effectively used to prioritize the severity of potential rock falls along other highways with similar geological and morphological settings.