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Resilient River Communities

Canterbury berm transition project clears 1,200 rugby-fields’ worth of exotic weeds

Co-investment between Canterbury Regional Council (Environment Canterbury) and Kānoa - the Regional Economic Development & Investment Unit gave the Canterbury region a unique opportunity to roll out a regionwide berm transition project - a targeted and strategic programme of weeding and underplanting along its rivers - helping to make them stronger, safer and more resilient. 
Environment Canterbury

Berms are the managed areas between the active braid of the river and the stopbanks. Together with stopbanks and trees, these river berms play a critical role in flood protection, helping to slow flood water and absorb force. More than 60 berm transition sites, mapped here, have been established across the region with 60ha of wetlands cleared of weeds, and the equivalent of 1,200 rugby fields’ worth of exotic weeds, gone.    

Weeds are a significant risk to river berms as they smother flood protection trees which if compromised can increase erosion risk to stopbanks and other essential infrastructure, decrease natural habitat diversity and negatively impact the overall resilience of rivers. Clearing weeds allows the river more space to spread and braid – something that is both rare and valued as part of the Canterbury landscape. Canterbury has the largest number of braided rivers in New Zealand.  Extensive native plantings alongside these rivers, also undertaken through this programme, will lower the chance of the weeds reinfesting.   

As of August 2023, the project has reached the following milestones:   

  • Over 45 contractors involved in the project to date   
  • 80% of them local businesses, 19% Māori-owned businesses   
  • 130,606 total hours worked by both contractors and internal staff   
  • The monthly hours worked averages the equivalent of approximately 816 fulltime employees (FTEs)

This regionwide project is increasing the resilience of berms, making them more resilient to flood damage and helping to protect productive farmland, communities and public infrastructure, enhancing environmental values and enabling opportunities to establish community recreational areas.    

Find out more about this project

Photo caption: Gravel groynes have been placed at a 45-degree angle to the river flow at this site on the Ashburton River/Hakatere to deflect flood flows back into the fairway. Willow poles (young tree stems) and anchored tree protection (ATP) have also been installed in order to re-establish the river berm and provide much improved protection. As an innovative trial we have also included native species in the scour bay to boost vegetative cover.