Flood Response in the Waimakariri District

The Waimakariri District lies to the north of the Waimakariri River in North Canterbury. It covers an area of approximately 2,250 km², and has a population of about 55,000 in rural and urban areas.

Heavy rainfall in June 2014 resulted in widespread flooding across the district including in the towns of Kaiapoi and Rangiora, and the rural residential areas of Fernside, Ohoka and Mandeville. This was compounded by high groundwater throughout the winter causing groundwater resurgence (or springs) and issues with rural drainage and the operation of Septic Tank Effluent Pump (STEP) systems.

In response to this flood event the Waimakariri District Council set up a Flood Team including consultants and Council staff, reporting to a Project Control Group, to rapidly investigate issues and deliver solutions. The Flood Team brief included four phases of work: Response and Reconnaissance; Identify and Implement Quick Wins; Identify and Investigate Permanent Solutions; and Review Systems and Processes. The works that resulted from this included immediate maintenance works, plus quick design and implementation of key upgrade works, while keeping in mind and developing longer term solutions.

Throughout the project there was a strong focus on communication and consultation with the affected communities. This included public meetings, weekly email and website updates, on-site meetings and communication with individuals.

This paper explores the flooding issues in the district, the challenges faced, and the process worked through by the Flood Team. It also describes some of the solutions adopted, both physical works and changes to Council systems and processes, maintenance practices, and funding.