Natech Risk from Floods. Vulnerability of Critical Technical Systems Containing Hazardous Substances

Natural hazards, such as earthquakes, floods, landslides, lightning, strong winds, etc. can cause release of toxic substances, fires and explosions when they affect critical technical systems of industrial plants that treat, store or transport dangerous substances (e.g.: pressure tanks, heat exchangers, columns, pipes, atmospheric tanks, etc.). This type of event is called Natech (Natural Hazard Triggering Technological Disasters). Among the natural events that can impact industrial plants are floods (river floods, high water, debris and mud flows, flash floods); they are a recurring but often overlooked characteristic also considering the climate changes we are experiencing. A lack of awareness of this type of natural hazard can significantly limit the effectiveness of management approaches against Natech incidents. In this work, authors propose to analyze vulnerability of the critical technical systems listed above following flood events, introducing a vulnerability index "IV". Flood vulnerability index "IV" depends on:“IVes”: Type of equipment, process storage conditions of the dangerous substances contained;“IVdm”: Main Flood Damage to Critical Equipment Mode. “IV” is obtained as the average of “IVes” and “IVdm”. This paper, after having determined the value of “IV” for single technical system, lists the main prevention and mitigation actions inherent to flood events. Keywords: Critical technical systems, hazardous substances, floods, natech risk, Seveso directive, vulnerab