Waimakariri flood protection project
The $40 million Waimakariri flood protection project will reduce the risk of flooding in Christchurch city and Waimakariri and Selwyn districts. It will add strength and resilience to the flood protection system already in place and significantly lower the risk of break-out during major flood events.
Construction began in 2010, with a proposed completion date of 2019. Once finished, the secondary stopbank system will provide back-up flood protection for the already high level provided for Christchurch.
Other important works include an upgrade of primary stopbanks and rock bank work to improve protection for parts of the Waimakariri and Selwyn districts and the Coutts Island and McLeans Island areas.
The first 15-kilometre length of secondary stopbank has been completed and runs from the Northern Motorway Bridge to Cross Bank at McLeans Island. The flood protection on the northern side of the river has also been strengthened through stopbank upgrades and rock lining.
The remaining work requires building of a 15km length of secondary stopbank extending upstream to Thompsons Rd at Halkett.
The primary system provides a very good level of flood protection and is designed to protect people in Waimakariri, Selwyn and Christchurch from a 500-year flood event. Even so, if the primary system were to breach, it could result in major floods through urban areas of Kaiapoi and Christchurch. This is why we are carrying out the project works now.
Many areas in Canterbury have been struck by major floods over the past 150 years. In Christchurch, floodwaters were sometimes knee-deep in the central city in the late 1800s and early 1900s.
During early European settlement, regular river overflows occurred over the floodplain areas in and around Christchurch and Kaiapoi. Since the primary stopbank was completed in the 1930s, the Waimakariri River hasn’t flooded through the city.
The most recent break-out, which occurred in December 1957, flooded parts of Coutts Island in Belfast and Kainga.