Waipaoa Flood Control Scheme Upgrade – priority stopbank work to protect Gisborne

This project aim is to increase the level of flood protection of the Waipaoa Flood Control Scheme to a 100yr return period accounting for climate change effects out to the year 2090.

The WFCS comprises approximately 64km of stopbanks along the Waipaoa River, together with other river control structures and protection works (pipes, floodgates etc), built in the 1950’s and 60’s to provide flood protection to the Poverty Bay floodplains and Gisborne City.

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

Resource Consent to undertake the stopbank improvement work was granted on 26 October 2018. Construction work first started in February 2019.

Up to February 2023, about 32 km of the Waipaoa Stopbanks have been successfully upgraded, both on the eastern (city) side and western side of the Waipaoa River:

• 4.2 km of stopbanks upgraded between Caesar and Ferry Roads near Ormond, eastern side. Completed December 2019. Compacted Vol = 142,620 m3.
• 2 km of stopbank improvements near the Waipaoa Rivermouth approx. between the KiwiRail Bridge and Te Arai Stream confluence, eastern side. Completed February 2020. Compacted Vol = 48,414 m3.
• 2 km of stopbanks located between the Waipaoa river mouth and the Railway Bridge. Completed November 2020. Compacted Vol = 22,000 m3.
• 4.1 km stopbanks located between the Willows/Dunstan Road intersection & Waipaoa SH2 Bridge. Completed March 2021. Compacted Vol = 76,000 m3.
• A 3m wide x 8km length of gravel ‘cycle trail’ has been installed in May 2021 between the Matawhero Bridge and Centennial Marine Drive. Special 'cattle stop ramps', signage and squeeze gates were all installed over April -June 2022. Cycleway officially opened on 01 July 2022 onwards.
• Around 3km of 7.8km of stopbank construction work upstream between Matawhero SH2 Bridge and Ferry Road was completed up to June 2021, before winter suspended works. Estimated compacted Vol = 188,000 m3.  Works restarted on 04 Nov 2021. Earthworks were completed in February 2022 for this section.
• 0.88 km of stopbank were upgraded between Ford Road and just upstream of Caesar Road. Earthworks were completed in February 2022 for this section. Vol. 17,000 m3.
• 3.25 km of stopbanks were upgraded between Kaitaratahi Hill and Whitmore Road. Earthworks were completed by late March 2022. Compacted Vol. = 54,000 m3. Noted Waipaoa River flooded on 24 March 2022 (8.3m high at Kanakanaia Bridge) which suspended construction, and halted earthworks for remainder of construction season.
• 4.3km of stopbank upgraded upstream from gun club to the Manutuke bridge on the Western Side of the Waipaoa River on 22 Nov 2022.
• 1.9km of stopbank upgraded between the gun club and the river mouth with the construction on the remaining 200m for that section stopped due to unfavourable ground conditions in Dec 2022.
• 2.2km of stopbank upgraded between Opou Road and the Whatatuna Floodgate in Feb 2023.
• Flood mitigation works involving ring-banking, and drainage improvement works on Wi Pere Trust have been completed in Dec 2023.
• Sheet pilling for construction of the Spillway at Wi Pere Trust started in March 2022.  The spillway construction was largely completed by Feb 2023 which had been stopped by cyclone Gabrielle. Wi Pere Trust land is located on the western side of the Waipaoa River across from Ormond Township.

• Mahunga Floodgate construction (8m high / 100t of steel / 340m3 of concrete) started in Feb 2022, with works delayed over winter and ongoing wet weather. Earthworks construction to tie into the adjacent stopbank also expected to be completed by April 2023.
• Stopbank upgrade works on the true right bank were underway from early Oct 2022. Stopbank upgrades and associated infrastructure renewals will continue progressively in an upstream direction (northwards) until the full upgrade of the western side is completed (around 2029 depending on funding).

Planning, investigation and design is also continuing for future stopbank upgrade areas, all of which are located on the western side of the Waipaoa River.