Te Mahinga Ārai Waipuke o Waipaoa

Waipaoa River Flood Control Scheme

Flood control climate change resilience project

In 2020 the government declared a climate change emergency, recognising the need for us all to prepare for the impacts of a warming climate, with more erosion, more flash floods and wildfires in our region.

Climate change is the most significant long-term issue facing our region. We’re expecting sea level rise, coastal erosion and floods affecting homes and recreation.

We need flood protection to keep our people and community safe from our rivers breaking their banks in heavy rains. We also need to ensure that our important horticulture, viticulture and farming assets are protected from the effects of climate change.

Council therefore wants to accelerate the delivery of our Waipaoa Flood Control Climate Change Resilience project, giving greater protection our community needs against floods, safeguarding both economic development and wellbeing.

The project’s aim is to increase the level of flood protection of the Waipaoa River to cater for a 100-year heavy rain event, accounting for climate change impact (sea level rise and larger rain events) out to 2090.

The original Waipaoa Flood Control Scheme was designed in 1949 and was completed in 1969. It's considered to be one of Council’s most valuable assets and protects some 10,000 hectares of fertile floodplain land. Construction work to improve the scheme started in February 2019 and involves upgrading approximately 64km of stopbanks along the Waipaoa River by 2031 or 2035, pending the outcome of community consultation.

As well as making the stopbanks higher, construction work will widen the stopbank profile from the current 1.5m top crest to 4m. Stopbank heights are being increased by about 1-2 metres in some places.

Approximately 10km of stopbanks along the Waipaoa River have been successfully upgraded since construction work started in 2019.

Construction work is steadily progressing upstream.

The focus in the first 3 years will be on upgrading the eastern side stopbanks to protect Gisborne city, followed by upgrading the western side stopbanks from 2024 onwards to complete all improvements by 2031.

To date, 6km of stopbank has been upgraded since construction started in February 2019. Between October - December 2020 we upgraded 2km of stopbanks on the eastern side between the Waipaoa River mouth and the Railway Bridge.

Oct 2020 - Feb 2021 - upgrade 4km of stopbank, eastern side between Willow/Dunstan intersection and Waipaoa SH2 Bridge.

Feb 2021 onward - from Waipaoa SH2 Bridge working upstream

2028: Project completed and scheme fully operational.

Total project cost estimate - $32-35 million

What the experts now say

Community consultation about 3 years ago, nearly 60% said we should stick with spending at the same level.

Since then, experts have told us higher and thicker stopbanks are needed to provide the full level of protection we need. This means increased costs of $13.2m.

We’ve now asked our community whether we should finish the project as planned by 2030 and pay the extra $13.2m, or should we extend the timeframe of the work, finish later and pay extra for inflation.

Protecting our region from flood

In August 2020 Council was awarded $7.5m external funding by the Provincial Development Unit to accelerate the delivery phase of the project.

During formal consultation of the 2021-2031 Long Term Plan, we’re consulting with our community on the way forward with protecting our region from floods. The options are to continue as planned or extend the timeframe.

Council’s preferred option is to continue as planned and invest the extra $13.2m to finish the Waipaoa River Flood Control Climate Change Resilience project. This option would give communities within the floodplain a higher level of protection from floods by 2030 at a cost of $33.3m. It would increase our overall rates and debt, but we would remain within our proposed debt limit.

The alternative option our community can consider is to extend the timeframe for this project to 2035. This would mean the Poverty Bay Flats would remain vulnerable to flooding until then. We would prioritise upgrading stopbanks in populated areas first. But until the upgrades are complete, the whole area remains at a higher risk of flooding. Our debt levels would be lower as the project would have a longer construction timeframe, but the total project cost would increase due to inflation. This option would see us spend around $26m during this LTP cycle but would result in an expected completion cost of $38m.