Tsunami damage and post-event disruption assessment of road and electricity infrastructure: A collaborative multi-agency approach in Ōtautahi Christchurch, Aotearoa New Zealand

Abstract

Coastal infrastructure are critical to the effective operation of society, but are highly susceptible to tsunami impacts. There are limited studies in the tsunami risk assessment discipline on network scale impacts of a tsunami to critical infrastructure. This study proposes and tests a framework (consisting of hazard, exposure, vulnerability and impacts) for tsunami impact assessment of critical infrastructure. The framework is applied through a collaborative case study approach between researchers and practitioners to co-develop a deterministic tsunami impact scenario, including road and electricity network component damage, spatio-temporal service disruption and restoration estimates (roads) in Ōtautahi Christchurch, Aotearoa New Zealand. A series of workshops were conducted with the Christchurch City Council (local government) and Orion Group (electricity distribution) throughout the impact assessment process to validate, refine and contribute to inputs, methods and results of this impact scenario. Results indicate that several coastal suburbs could be isolated for 3–44 days, with 10–44 days required to reinstate all routes. Results provide inputs for informing mitigation initiatives for asset managers, planners and emergency managers. Results are used to inform recommendations for increasing tsunami resilience, including land-use management, emergency response planning, infrastructure component mitigation and network mitigation. This study contributes to the tsunami risk assessment discipline, specifically providing a framework and case study for estimating road and electricity network impacts from tsunamis. The framework and associated methodology presented in this study are applicable to other coastal urban environments exposed to tsunami hazards, for assisting in initiatives that increase tsunami resilience.