Increase in spatial extent and duration of outages in water distribution networks from increasing temperatures

Civil infrastructure systems are vital for delivering resources, providing protection, and facilitating many critical activities. Typically, these systems are designed to last for a long time, often on the order of decades,... [ view full abstract ]

Civil infrastructure systems are vital for delivering resources, providing protection, and facilitating many critical activities. Typically, these systems are designed to last for a long time, often on the order of decades, with some systems persisting for over a century. Infrastructure limits of operation are designed based on historical climate conditions, and global climate models project that these conditions no longer represent the exposure that infrastructure will see in the future. One particular hazard is temperature rise in already hot climates. Water treatment and distribution systems are particularly critical to the economic health of a city, especially in hot conditions. The delivery of safe and sufficient water to residents and commercial establishments is vital to almost all residential, commercial, industrial, and public operations. It is especially important that water systems remain reliable as temperatures rise because in addition to greater potable water consumption, the viability of many services may also require increased water consumption. The electricity generation and agriculture industries in particular may need increasing amounts of water into the hotter future, and the delivery of this water is dependent upon both the availability of the resource, and the reliability of the infrastructure. When both the availability and infrastructural reliability is stressed by rising temperatures, there could be a significant threat of provisional inadequacies and consequential economic losses in hot regions of the world.

Past research has shown that with the increase in ambient temperatures in hot regions from climate change, the frequency of outages to the consumer from infrastructural failures could increase by up to 131% by 2050 under certain system designs, maintenance practices, and climate projections. It is unknown however, where the outages would occur within a region and if the spatial extent and durations of outages could also increase from temperature rise. Through assigning increasing stochastic failure rates to infrastructural components and running time simulations of the components in a geospatial water distribution network, the neighborhoods which could be affected and what the actual impact from water outages might be is estimated. A standard water network with the temperature projections of Phoenix, Arizona is used as a case study because Phoenix is a city that is projected to experience significant increases in temperatures. From a measure of how many nodes fall below the threshold of 20 psi throughout a simulation period of around 80 years, the duration and spatial extent of these water outages has now been projected out until 2099. We find that the annual number of nodes and the length of time that nodes fall below the threshold steadily increases throughout this century. Thus, water utilities are faced with the challenge of adapting their system design and maintenance practices to reduce the impact of consumer outages into the future.