Heavy Rainfall, Debris Flow Hazard and Powerline Vulnerability: the Case Study of Talamona Event

The power system is the backbone of the energy system and overhead lines are their vital structures. Weather threats may jeopardise the reliability of lines and make them a weak link. In particular, heavy rainfall episodes can cause failures, especially in mountain areas. In this context, debris flows triggered by heavy precipitations can destroy pylons not only in the upper ridges but also downstream across the fan apex where lines are much more distributed across the landscape. This study presents a back analysis of a debris flow event that occurred in Talamona (Sondrio Province, Italy) in July 2008. This event hit powerlines causing local blackouts and showing the potential vulnerabilities of the local electro-energy system. An analysis of failure detection using the numerical model CRHyME (Climatic Rainfall Hydrogeological Modelling Experiment) and MIST-DF (Modelling Impulsive Sediment Transport – Debris Flow) is carried out to reconstruct the dynamic of the rainfall-induced geo-hydrological event. Powerline vulnerability is also investigated against debris flow dynamic, discussing possible strategies to reduce pylon exposure and to increase the resilience of the local electro-energetic network. The learnings from the reanalysis of a past event confirm the strength of the approach and foster its use in different situations.