A graph-based exposure representation of elemental failures in alpine water distribution networks&#160;
Authors: Satish Rahul , Oberascher Martin , Sitzenfrei Robert 
Published: March 2024

A continuous and reliable drinking water supply is crucial for the social well-being and economic growth of an area. Therefore, water distribution networks (WDNs) are a critical component of the urban infrastructure, ensuring the delivery of potable water to users. However, these systems are vulnerable to loss of function and reliability when confronted with failure scenarios. Crises scenarios like cyber-physical attacks or contamination, pandemic with changes in consumption due to social distancing regulations, uncoordinated withdrawal of drinking water for storage purposes or loss of knowledge due to personnel changes could have an impact on WDN resilience. These disturbances can strain the physical elements, affecting both water quantity and quality. However, the exposure of various elements to diverse disturbances is multifaceted. Understanding the interplay between failure scenarios and potentially affected elements within the network is crucial for improving the resilience of the WDN. To further enhance the understanding between these dependencies, this work links specific failure scenarios with their corresponding impacted elements in an exposure matrix and highlights the varying importance of these elements in the WDN by a hierarchical graphical structure.The research consists of two phases. The first phase encompasses the identification of classical and emerging failure scenarios through a literature review. Thereby, 29 failure scenarios are categorized into 7 groups (water infrastructural failure, natural hazards, contamination, pandemic, attacks, other infrastructure/elemental/factor failures, and digital disruptions). Additionally, WDN elements are defined using a literature review and expert input for the field of water distribution.In the second phase, investigation and documentation of WDN elements affected by these failure scenarios, specifically for Alpine WDNs, are conducted. Information is gathered through literature review and workshops with experts in the field. The outcomes are organized into three exposure matrices based on failure types (physical elements, quality, and quantity) resulting from failure scenarios affecting the WDN. For instance, during a river flood, diverse network elements such as ground-water wells, water treatment plants, pipes, valves, pumps, and hydrants may be adversely impacted, influencing both water quality and quantity in the WDN. Elevation tanks and springs remain impervious to river floods due to their elevated positioning, preventing floodwaters from reaching these structures and ensuring their resilience against the event. Finally, the exposure-matrix is a graphical representation that illustrates the relationships between different elements in a system and their vulnerabilities to various failure scenarios. A network graph is used to visually represent the exposure-matrix in a topological hierarchy. The results can offer guidance for WDN operators in risk assessments, providing an exposure matrix to anticipate potential elemental failures during disasters, thereby proactively setting action and enhancing the overall resilience of the WDN.Funding: The project &#8220;RESIST&#8221; is funded by the Austrian security research programme KIRAS of the Federal Ministry of Finance (BMF).