Ashley River/Rakahuri vegetation clearance

The Ashley River/Rakahuri is a key feature of the North Canterbury landscape that poses a significant flood risk to the communities living on its floodplain. This project involves removing exotic vegetation (willow and brush weeds) choking a section of the river between Ashley Gorge and the Ōkuku River confluence, and in the Ōkuku River.

Vegetation risk management

Exotic vegetation is a flood and erosion risk, occupying the channel and forcing floodwaters towards farmland. Weed growth can also contribute to the loss of aquatic habitats and nesting areas for native birds.

The clearance area in this project is divided into two locations:

  • Location one: A 15-kilometre section of the Ashley River from Ashley Gorge (about 536ha)
  • Location two: An 8-kilometre section of the Ashley River, from the end of Location 1 to the Ōkuku confluence and approximately 7.5 km upstream in the Ōkuku River to just west of the Grey River confluence (about 140 ha).

Vegetation clearance area

Location one on the Ashley River/Rakahuri

The physical clearance of vegetation at location one was completed in March 2022.  

Location two on the Ashley River/Rakahuri

The physical clearance at location two was completed in several stages.  

The clearance of the main area on the Ashley River, from the end of location one to the Ōkuku confluence was completed at the end of 2022. 

Vegetation clearance of site one on the Ōkuku River (above Birch Hill Road bridge) was completed in May 2023.

Works on site two (on the Ōkuku River to just west of the Grey River confluence) were completed on 1 July 2023. This included deep-planting willows to stabilise the banks (see bottom right of the Ōkuku River image), Anchored Tree Protection (ATP) and construction of a gravel bank at the breakout site (see centre of the image), along with clearance of the island to promote braid mobility and increase flood capacity (see centre left of the image).

The properties affected by the 2021 floods now have a much greater level of flood resilience, with the full extent of the flood protection works undertaken to be achieved once plantings have fully established root networks. 

Remaining work

There is one final round of ground spraying at location two remaining to tackle the spring weed regrowth. This final spray will mark the completion of the Ashley River/Rakahuri vegetation clearance project.