The electric system infrastructure is subject to threats, from a variety of sources, that can cause damage and disruption. To mitigate this risk, electric utilities are committed to preparing plans to increase resilience. In this paper, a study is reported to identify the main hydrogeological hazards faced by the Italian National Transmission Electricity Network (RTN) and to research available data and methods for their quantification.

Quantification in terms of hazard type and intensity parameters is, in fact, the first fundamental step in the preparation of resilience plans. In the case of hydrogeological disruptions, the main disruptive phenomena are floods and landslides, to which our country is unfortunately widely exposed. Since the Network is extended over the entire national territory and the objective in this study is to provide useful elements for the preparation of a resilience plan that encompasses it in its entire extent, the search for data and methods is aimed at obtaining results at that scale.

To this end, the focus is on expeditious methods of analysis, based on data that are uniformly available for the entire national territory, and which are able to provide rapid first-approximation assessments over large areas.

IThe study therefore began by analyzing a sample of incidents over the last 10 years provided by Terna, the operator of the national transmission grid. The results confirm that floods and landslides are the most common causes of hydrogeological blackouts.

The most recent updates of national mapping, prepared by the relevant authorities, of areas prone to flood and landslide hazards were then analyzed, with particular attention to the type of parameters and their digital format for the purpose of use with geographic information systems. The spatial intersection of the sample failure cases with the mappings showed that, in the case of floods, most of them are identifiable through the existing mappings, while on the contrary the cases due to landslides to a large extent do not fall in mapped areas, most likely due to the fact that they are often small local landslide events that nevertheless caused plants to fall on power lines.

Based on this finding, the study proceeded, on the one hand, with the implementation of a computational module to estimate the values of water heights and velocities at points of interest within the areas mapped as floodable; on the other hand, with the analysis of methodologies proposed in the literature useful for the implementation of rapid methods to identify hazardous situations, both for floods and landslides, not included in the currently available maps.