2023 – Emergency Response for Urban Stormwater Dams in a Large-scale Flood Event

Dewi Knappstein, Kevin Ng, Jayesh Solanki

Auckland Council owns and operates approximately 600 stormwater ponds and wetlands, most of which involve dams. This valuable infrastructure supports the financial, social, cultural, and environmental wellbeing of communities, present and future, by providing flood mitigation, water quality treatment, amenity, ecological value, and cultural heritage value, as well as mitigating the impacts of land development and climate change.

In the first few months of 2023, the Auckland region was subject to two catastrophic storm events in quick succession, including Auckland’s largest ever rainfall event. This paper shares the experience from the emergency response for a large portfolio of stormwater dams in a region- wide, multi-month series of record floods, to share learnings with others that may face similar situations.

Several factors were identified as beneficial for emergency response. These included having a mature dam safety management system, a practiced response team, and pre-established relationships with dam safety advisors and contractors. In a series of large-scale storm events, other hazards will likely need to be considered alongside the dam safety threat, the health, safety, and wellbeing of the response team requires extra consideration, and there is especial value in simple systems and concise communication.

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