New Resilience Index for Urban Water Distribution Networks

The increased frequency of natural disasters and man-made catastrophes has caused major disruptions to critical infrastructures (CI) such as water distribution networks (WDNs). Therefore, reducing the vulnerability of the systems through physical and organizational restoration plans are the main concern for system engineers and utility managers that are responsible for the design, operation, and protection of WDNs. In this paper, a resilience index (R) of a WDN has been proposed that is the product of three indices: (1) the number of users temporarily without water, (2) the water level in the tank, and (3) the water quality. The resilience index is expected to help planners and engineers evaluate the functionality of a WDN, which includes: (1) delivering a certain demand of water with an acceptable level of pressure and quality, and (2) the restoration process following an extreme event. A small town in the south of Italy has been selected as a case study to show the applicability of this index using different disruptive scenarios and restoration plans. The numerical results show the importance of the partition of the network into districts to reduce the lack of services. It is also necessary to consider the indices separately to find trends that cannot be captured by the global index. Advantages and disadvantages of the different restoration plans are discussed. The proposed indices can be implemented in a decision support tool used by governmental agencies that want to include the restoration process, and the environmental and social aspects in their design procedure.