Flood recovery updates

The north branch of the Ashburton river in floodHere you can find regular updates on the status of our rivers and the progress of flood recovery works. We anticipate that flood recovery work will last several years with some repairs only being able to be done during drier summer conditions and vegetation re-planting only over winter. 

The May 2021 flood event was an unprecedented weather event with both long and intense periods of rainfall with effects felt from the Waimakariri District through to the Mackenzie.

In the Ashburton River/Hakatere catchment area the weather event was of a magnitude greater than everywhere else in the region.

Flood damage repair progress

By June 2022 most of the major structural flood damage repairs had been completed and erosion protection tree planting was the focus. Wider repairs of damaged infrastructure from the 2021 event were on track and on budget.

In the winter of 2022 several high flow events occurred in quick succession, causing some damage to the recently repaired yet still fragile flood protection infrastructure. In some areas there was new damage from these flows at locations not previously damaged in the 2021 flood.

Major stopbank repairs

Approximately 70 percent (more than 3.5km) of all the stopbank repair or rebuilding has been completed. Repairs to major sites are listed in Table 1. The remaining stopbank repairs are due for completion by the end of the summer of 2022/23.

Table 1. Stopbank repair works
Location Length (m)
Ashburton North at Thompsons Track 340
Ashburton South at Blacks Road 670
Orari at Inglis Road 950
Orari at SH79 230
Orari at railway bridge 130
Waihī at Hawke Road 550
Ōpihi at Collett Road 120
Ashburton North at Walkhams Road 290
Waihī at Beeby Road 190
Ōpihi at Mill Road 150
Total 3,620
South Ashburton, Blacks Rd

South Ashburton at Blacks Road completion of replacement stopbank, February 2022

North Ashburton, Thompson Rd

North Ashburton at Thompsons Track -  Completed stopbank repair, 16 March 2022

Other major repair works

Other major repairs that have been completed have included the re-establishment of rock groynes, implementation of “Hayman” and “rope and rail” fences in areas of bank scour, and installation of anchored tree protection. The larger of these works are listed in Table 2:

Table 2. Other major works
Location Description
Ashburton at River Road Groynes and anchored tree protection to replace 310m of tree edge protection lost.
Orari at racecourse Rope and rail fencing and infill planting to replace 160m of tree edge protection lost.
Waihī at SH79, Geraldine Rope and rail “Hayman Fence” to replace 190m of tree edge protection lost.
Waihī at Geraldine NPD Rebuild four rock groynes and add two new groynes to replace existing rock groynes and 150m of tree edge protection lost.
Waihī at Geraldine High School “Hayman Fence” bank repair and native planting to replace 120m of tree edge protection lost.
Waihī at Geraldine, repaired rock groynes (looking downstream). March 2022.

Waihī at Geraldine, repaired rock groynes (looking downstream). March 2022.

Waihī at Geraldine High School embankment with Hayman Fence and native vegetation plantings, 9 August 2022.

Waihī at Geraldine High School embankment with Hayman Fence and native vegetation plantings, 9 August 2022.

Tree edge protection reinstatement

Tree edge protection reinstatement has been undertaken at a number of sites. This has included installation of anchored tree protection (ATP) where needed and planting willow poles or wands to replace areas of tree edge protection lost. Major sites with ATP installation are listed in Table 3. This is the first step towards re-establishing the tree edge protection asset which will take several (5–10) years for trees to grow to where they provide the pre-flood level of river edge protection.

Table 3. Anchored tree Protection installation
Location Length (m)
Opihi at Collett Road 150
Waihi at Hawke Road 90
Waihi at Beeby Road 120
Orari at SH79 410
Orari at Inglis Road 820
Ashburton South at Walkhams Road 750
Total 2,340

In addition to anchored tree protection, infill planting between ATP has been started at a number of locations across the region. By 30 June 2022 approximately 30% of replanting had been achieved. An example of tree planting detail is shown in the following Figure:

Figure: Ashburton Area—Infill Tree Planting To replace tree edge protection lost in 2021 Flood. (a) Area upstream of Thompsons Track. Planned tree planting is marked in red. Completed tree planting by 30 June 2022 is marked in green.

Vulnerability to future flow events

All repairs remain highly vulnerable to future flow events and we’re aware that this is a really difficult situation for many landowners. Some rivers, particularly the Ashburton/Hakatere and Orari, remain susceptible to rainfall. In these rivers, any significant flows may result in break outs at the same places repairs have already been undertaken, until permanent vegetation edge protection can be established. 

We are in regular contact with MetService and, as always, our flood controllers are on duty 24/7 and fully aware of the vulnerability of our flood protection schemes. If we are alerted to the possibility of out-of-river flows, we will post information on our flood warning page and use our social media channels and the text alert system for proactive messaging if required. 

Flood recovery costs 

We expect the final cost of damage to our flood protection infrastructure to be around $22 million. This is an increase over our earlier estimate of around $20 million due to the additional damage caused by the winter high flows of 2022.  

This is the replacement cost for infrastructure on a ‘like-for-like’ basis and does not include any additional costs for potential improvements. 

Effects of climate change

As we consider repairs, we continue to assess the expected effects of climate change and modifying design solutions to incorporate this as part of our recovery work, rather than simply replacing the flood protection infrastructure that was in place. 

An example is the repair to the stopbank near Collett Road on the Ōpihi River where, rather than simply replace a stopbank, we modified the design to include building the new part of a stopbank further back from the river.


Ōpihi at Collett Road prior to stopbank repairs, 23 February 2022.

Ōpihi at Collett Road prior to stopbank repairs, 23 February 2022

Ōpihi at Collett Road, following completion of stopbank set further back from river, 23 March 2022.

Ōpihi at Collett Road, following completion of stopbank set further back from river, 23 March 2022

Flood repair job status map

Immediately following the flooding of 31 May – 2 June 2021 we undertook an assessment of all damaged flood infrastructure across Canterbury.

This resulted in a comprehensive list of sites needing repairs. These jobs have now been scheduled and prioritised according to a risk assessment.

View a live map of all the flood repair jobs currently identified by priority.