## 6 Rockfall Hazard Assessment in the Study Area
### Rockfall Hazard Assessment  
According to the reclassification results of the kinetic energy, passing height, and passage number of falling blocks, the vector values of (R, H, V) for all the rasters were obtained. According to values of |RHV| (as shown in Table 4), the rockfall hazard in the study area was divided into three levels: I [4.123, 5.196], II [3; 4.123], and III [1.732, 3], corresponding to a hazard level of high, medium, and low, respectively. The hazard mapping results are shown in Figure 9.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline
**C** & **H** & **V** & **|RHV|** & **Rank** & **C** & **H** & **V** & **|RHV|** & **Rank** & **C** & **H** & **V** & **|RHV|** & **Rank** \\ \hline
1 & 1 & 1 & 1.732 & III & 2 & 1 & 1 & 2.449 & III & 3 & 1 & 1 & 3.317 & II \\
1 & 1 & 2 & 2.449 & III & 2 & 1 & 2 & 3.000 & III & 3 & 1 & 2 & 3.742 & II \\
1 & 1 & 3 & 3.317 & II & 2 & 1 & 3 & 3.742 & II & 3 & 1 & 3 & 4.359 & I \\
1 & 2 & 1 & 2.449 & III & 2 & 2 & 1 & 3.000 & III & 3 & 2 & 1 & 3.742 & II \\
1 & 2 & 2 & 3.000 & III & 2 & 2 & 2 & 3.464 & II & 3 & 2 & 2 & 4.123 & II \\
1 & 2 & 3 & 3.742 & II & 2 & 2 & 3 & 4.123 & II & 3 & 2 & 3 & 4.690 & I \\
1 & 3 & 1 & 3.317 & II & 2 & 3 & 1 & 3.742 & II & 3 & 3 & 1 & 4.359 & I \\
1 & 3 & 2 & 3.742 & II & 2 & 3 & 2 & 4.123 & II & 3 & 3 & 2 & 4.690 & I \\
1 & 3 & 3 & 4.359 & I & 2 & 3 & 3 & 4.690 & I & 3 & 3 & 3 & 5.196 & I \\ \hline \hline \end{tabular}
\end{table}
Table 4: Classification criteria of rockfall hazard assessment in study area.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Rank** & **c/NO. (Standardized)** & **k/Kinetic Energy (kJ)** & **h/Height (m)** \\ \hline
1 & \(<\)0.2 & \(\leq\)2500 & \(\leq\)5 \\
2 & 0.2–1 & 2500–40,000 & 5–10 \\
3 & \(>\)1 & \(\geq\)40,000 & \(\geq\)10 \\ \hline \hline \end{tabular}
\end{table}
Table 3: The parameter reclassification criteria of rockfall hazard assessment (Modified from [PERSON] et al. [18]).  
Provincial highway 306 in the study area is located on the right bank of the Yarlung Tsangpo River; thus, it is mainly affected by the rockfalls on the right bank. The length of the 306 provincial highway is 91,620 m in the study area, and the length affected by rockfall is 10,010 m, accounting for 10.92% of the 306 provincial highway in the study area. The total length of the transmission line is about 60,860 m in the study area, and the length affected by rockfall is 5710 m, accounting for 9.38% of the transmission line in the study area. The number of pylons affected by rockfall is 17, and the numbers located in high, medium, and low hazard areas are 6, 6, and 5, respectively. Here, we have mentioned that the public infrastructure was exposed at rockfall hazard. According to [PERSON] et al., this is one of the components of risk [36]. Since the highway and pylons are inanimate objects, the rockfall risks they take basically depend on the rockfall hazards of the locations where they are. Therefore, pylons within high risk zones of rockfalls are concentrated on the east part of the study area. The partitions of highway within high risk zones are concentrated on the central and east parts of the study area.