Quantitative risk assessment for rainfall-induced landslides of transmission line towers: the case of Chongqing national transmission protection regions

In recent times, the increasing frequency of geohazards has been threatening the safe and effective operation of power transmission networks. However, the quantitative risk assessments of landslides for transmission towers remain underdeveloped. The present study aims at providing the quantitative landslide risk distribution along the Chongqing National Transmission Line Protection Regions (NTLPR) in China by establishing an original technical framework. Particularly, both static and dynamic data are used for modeling the susceptibility and hazard of landslides. Then, the potential vulnerability of transmission towers to landslides was assessed based on the distance between the towers and landslide run-out boundaries. Finally, following the classical risk assessment theory, the quantitative risk distribution maps of towers affected by landslides is established. The results showed that landslide hazard exhibits a consistent variability in relation to the spatiotemporal distribution of rainfall erosion intensity. As landslide data is updated and mitigation measures are implemented, both the vulnerability and risk associated with the towers undergo dynamic changes over time. The vulnerability curve analysis reveals transmission towers within 274 m of landslide run-out boundaries exhibit very high vulnerability level, with potential losses of 1 million RMB per tower. Specifically, the number of high/very high vulnerability towers was reduced from 487 (2002–2010) to 75 (2019–2020), resulting in a 65.83 % decrease in overall risk (from 103.83 to 35.48 million RMB). The obtained results provide an interpretable risk mitigation scheme for the management of power transmission networks, and are expected to become an effective framework for landslide management in the power industry.