River works and flood protection repairs
- In the Ashburton River/Hakatere and Hinds River catchments there are 14 active work sites, 25+ machines in action and additional jobs pending. Click the map below to see these, as of late Wednesday afternoon (9 June) (JPG file, 249 KB).
- It’s really important to have a full-time engineer in Ashburton at this vulnerable time and we will have someone based locally over this coming weekend and likely into next week.
- Land survey staff are in the field collecting critical information for flood modelling.
- Field staff continue to work in the field collecting damage information and logging more jobs.
- LiDAR is being flown.
- The weather forecast is for mostly dry conditions for the remainder of the week, so we don’t expect any rises in river flows across the region.
- Monitoring will continue at vulnerable sites.
General rivers operations update
- Te Waihora/Lake Ellesmere remains open to the sea today, Sunday 6 June. The cut has naturally developed to 45m and there is a rough sea. A digger is working to help develop the cut further. The lake level is starting to drop but there may not be a dramatic drop until the cut scours wider.
- There are now 14 active river work sites in Ashburton. Contractors are being supervised in the field by teams of Environment Canterbury staff and river engineers from other regional councils.
- At the Orari River, water has now been pushed away from two break out areas, and the sites are being strengthened by machinery today. There is machinery at the third break out site now doing the same.
- River levels may rise by small amounts, but we do not expect any out-of-river flooding.
- We will continue to monitor rainfall and river levels closely, and we have response teams on standby in case they are needed.
Canterbury flood response works
Environment Canterbury staff and contractors are in the field assessing flood damage and responding to priority issues in the wake of last week’s rainfall event.
We are currently assessing significant flood repairs on the Selwyn/Waikirikiri, Ashburton/Hakatere, Hinds/Hekeao, Orari and Waihi Rivers. Ashburton is particularly hard hit so we will have a full time dedicated Senior River Engineer onsite for at least the next week.
Here is a breakdown of some of the priority work currently taking place:
- Waihi River: Machinery is working on breakouts above Hawke Road and on re-establishing tracks for access so debris can be removed and the channel realigned around Beeby Road.
- Orari River: Two dozers will work over the long weekend to complete channel realignment. The banks has been pushed up to stop further overflow to Coopers Creek.
- Coopers Creek: A contractor will remove a fallen poplar and damaged bridge on a property Further work may be considered here.
- Halls Stream (Fairlie): Tree removal will occur on 8 June.
- Fairlie Township Creek: A contractor is on site fixing a scour.
- Hakatere / Ashburton River: The full list of damage is still being collated geospatially. Work on priority sites on the North and South branches is underway.
- Hekeao / Hinds River: Staff are in the field assessing priority issues for the Hekeao / Hinds River.
- Te Waihora / Lake Ellesmere opening: Work on opening the cut is progressing well and depending on weather conditions, the lake should be open to the sea this long weekend.
- Waikirikiri / Selwyn River: Inspections on the south bank are complete, and damage assessment on the north bank is underway.
- Okuku River: Flow diversion near Inglis Road is underway.
- Rakahuri / Ashley River: Training bank repair is underway near Waikuku.
- Cust / Eyre rivers: Damage assessment is complete.
- Waimakariri River: The Beach Rd / Pines Beach floodgate has been fixed, and the rock scour repaired. Rock repairs have been completed at a key site on the Lower Waimakariri.
General flood information
Notice on all other works
Please note, the following works may be on hold due to the May-June 2021 flood event.
Tree clearance – Ashley River/Rakahuri
In March we used helicopters to spray targeted weed species (specifically willows, alder, poplar, gorse, broom, and lupins) in the Ashley River/Rakahuri from the Ashley Gorge down to 1 km east of Cottles Road. We are now following this up with physical clearance of trees.
We are clearing trees (mainly willow and brush weeds), from a 14-kilometre section of the Ashley River/Rakahuri between Ashley Gorge and approximately 1 km east of Cottles Road.
WHAT: Works will be undertaken by our contractor, Canterbury Woodchip Supplies Ltd. The work will involve chipping trees with access to the river at public roads or some privately negotiated access points. There will be no roads or new tracks created in the riverbed other than where machinery will crush weed vegetation as the work is carried out.
Qualified Environment Canterbury staff and contractors carry out weed control measures in the open riverbeds to help flood flows pass through, and to enhance biodiversity values. Left unchecked the vegetation is a flood risk, occupying the channel and forcing flood waters towards farmland and riverside communities. Weed growth can also contribute to the loss of aquatic and terrestrial habitats for endemic fauna including native birds.
WHEN: Starting Monday 31 May until the end of September.
Waiau township stopbank project
What: Works will commence with reconstruction of the existing stopbanks on either side of the Inland Road Bridge (sites 1E and 1W on the map) and will be followed by construction of a 700 m long stopbank from Clarence Street to the Rotherham Road Bridge (site 2).
When: Starting Monday 24 May until about late August.
The Waiau township has been subject to many flood events from both the Mason River and Waiau Uwha. Numerous ad-hoc stopbanks were constructed over the past century, the earliest dating between 1907 and 1922 by the Waiau Riverside Protection Board.
This project will improve the level of flood protection to Waiau township through the remediation and strengthening of two existing stopbanks on Inland Road, and through the construction of a new stopbank which will border the eastern side of the town. It is expected that these works would protect Waiau township from flooding in a 200-year ARI (Average Recurrence Interval) flood event.
Partially funded from the Ministry of Business Innovation and Employment’s Provincial Development Unit (PDU) the Waiau township stopbank project increases flood protection and climate change resilience for the Waiau community. Funding from the Climate Resilience Programme of Flood Risk Management Projects has significantly reduced local community cost and helped kick-start projects that would have otherwise taken decades to fund through current rating districts.
Ashley River/Rakahuri stopbank - routine tree maintenance
What: We are undertaking some routine maintenance of trees on the Ashley River/Rakahuri stopbanks – on the true left bank from SH1 to Raupo berm.
When: Starting Monday 24 May for about three weeks until Friday 11 June.
Works involve trimming some large poplar tree branches that are currently overhanging the stopbank. We need to remove these as they are hazardous to people using the recreational track on the stopbank. We will also be undertaking some track upgrades.
During this period the stopbank access track will remain open. We will have someone on hand to manage traffic/recreational use of the area whilst works are in in progress. This may cause minor delays but will ensure that people are safe during the operation.
Rangitata River/Awa flood scheme recovery project
- What: ‘Making it safe’ – short term physical works to address immediate flood risk following the summer 2019 flooding. Works include extensions and construction of stopbanks, construction of gravel groynes and strengthening of rock stub groynes.
- Where: Five sites along the south bank of the Rangitata/Awa.
Flood flows in December 2019 across the West Coast and Canterbury caused significant flooding of the Rangitata River.
This programme of physical works will commence mid-April and is required to address the immediate flood risk to the Rangitata community from damage following the 2019/2020 flooding.
At a construction cost of about $1.3 million, the works are 64 per cent funded by the central government’s Climate Resilience Programme of Flood Risk Management Projects (initiated as part of the Covid-19 recovery response) which is administered by the Provincial Development Unit (PDU) of the Ministry of Business, Innovation and Employment (MBIE) in a co-funding arrangement. The remaining 36 per cent of the cost will be co-funded by the Rangitata River Rating District (Environment Canterbury), Waka Kotahi NZTA, Rangitata South Irrigation Limited, Kiwirail, Timaru District Council, Ashburton District Council and Transpower.
Lower Waitaki flood scheme recovery project
- WHAT: We are commencing flood protection works to remediate damage in the lower Waitaki River following the extensive flooding of summer 2019/20.
- WHERE: Twelve sites along the Lower Waitaki River.
- WHEN: We anticipate the majority of this work will be completed between May and October 2021 but acknowledge that at some sites the work may take longer. We aim to complete all works by February 2022.
Site-specific work plans are available in the attached remediation works summary (PDF file, 5.63MB).
Waimakariri River flood protection | McIntoshs bend rock works at Kaiapoi
Some restrictions to the area will be necessary to complete the work:
- February/March 2021 - Pegasus cycleway and walkway will remain accessible throughout construction by diverting the track through the adjoining paddock; except for the last week of February and first two weeks of March 2021, during which the oxidation ponds section will be closed. This is necessary in order for us to complete the stopbank rock armouring.
- Mid-April to July 2021 - fishing access will be restricted to one section of riverbank at a time. One section will close (either section A or section B) whilst the other will remain open to allow the riverbank works to be completed. No construction will take place on weekends or public holidays.
The Waimakariri and Kaiapoi River stopbanks are part of the Waimakariri-Eyre-Cust flood protection system. We will be strengthening the riverbank rock lining and placing stopbank rock armouring along the riverbank. We will also carry out improvements to the Ferry Road carpark, riverbank access tracks, and wetlands.
These upgrades will be carried out by Environment Canterbury, with funding support from the Ministry of Business Innovation and Employment’s Provincial Development Unit (PDU).