Earthquake damage to land and infrastructure alongside the Avon River has led to an increase in the severity of flooding to existing flood-prone land and to some new areas.
This has also had an adverse effect on land zoning, existing flood mitigation infrastructure, stormwater systems, critical roads as well as other services.
The Avon River Flood Protection Programme (FPP) is investigating options for flood management of stopbanks, pumping and other measures to restore flood risk to pre-earthquake levels. Future use of the residential red zone impacts on flood management options.
Cranford Basin is a critical part of the city's stormwater network, connecting the Avon and Styx River catchments. Investigations have focussed on boosting stormwater storage and maximising the effectiveness of the new Tay Street Drain Pump Station.
In February 2016, the Council agreed to a significant upgrade to the Cranford Basin stormwater network.
The agreed programme of works is estimated to cost $7million, including land purchase costs. Work will include the construction of embankments and upgrades to drains, floodwater storage areas, gates and systems in the stormwater network around Dudley Creek and Flockton. The works will be built in coordination with the proposed Styx River Stormwater Management Plan and Northern Arterial Motorway projects.
The work is expected to bring a substantial increase to stormwater storage capacity, and give greater control over flooding in the adjacent areas, including Flockton Street, St. Albans Creek, Shirley Stream, Upper and Lower Dudley Creek and the Ellington Road Estates Area.
The Dudley Creek flood remediation scheme is now operational, offering increased flood protection to more than 585 properties.
Before any work starts, works notices will be issued to residents in the surrounding areas, emailed to e-newsletter subscribers and put up on this page.
Flood mitigation works have started in the Knights Drain catchment, an area at greater risk of flooding since the earthquakes, due to ground subsidence.
Works have been split into three stages:
A new pump station and pressure main on ANZAC Drive to discharge water from Knights Drain into the Avon River.
Stage 1 was completed by SCIRT in 2017.
A new landscaped stormwater basin in the corner of Wainoni Park with some pipe upgrades in the surrounding streets.
Stage 2 is under construction, due for completion mid-2018.
A new stormwater pond on the corner of Pages Road and Anzac Drive including modifications to Knights Drain and the existing wetland.
Stage 3 is currently undergoing design and property purchase negotiations.
The Knights Drain construction programme is dependent on property purchases progressing.
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No.1 Drain is a 480-metre drain located in the Shirley Links Golf Course. The drain suffered extensive earthquake damage. Further failure could result in an increased flood risk and repair was needed to ensure the drain kept functioning.
No.1 Drain in Shirley, which runs into Horseshoe Lake, was badly damaged in the earthquakes.
The once unsightly concrete drain has now been transformed into a naturalised stream, complete with ponds and floating wetlands(external link), bringing reduced flood risk for properties upstream, and improved habitat for aquatic life.
The floating wetlands are densely bedded with plants, which will send their roots into the water and take up nitrogen, phosphates and heavy metals, improving the water quality in Horseshoe Lake and the Avon River.