Northcote has always suffered from terrible stormwater flooding. It’s located in the historic trajectory of the Awataha Stream and the middle of an overland flow path. As such, after heavy rain, the town centre and surrounding homes have historically been prone to flooding.
To address these flooding problems, as well as reconnect local communities with their awa using green infrastructure, Eke Panuku has been working with Auckland Council’s Healthy Waters team, Kāinga Ora Homes and Communities, Kaipātiki Local Board and mana whenua, in recent years, to put water sensitive design principles into practice.
With the record-breaking downpour in Auckland experienced on Friday 27 January, the new stormwater infrastructure in Northcote was tested to the max.
Two significant projects completed at the end of last year as part of Te Ara Awataha - Northcote’s new greenway - made all the difference in the face of the deluge that hit Tāmaki Makaurau. These were the daylighting of the Awataha Stream and the transformation of Greenslade Reserve into a stormwater detention park.
“Bringing the Awataha Stream to the surface provided better stormwater management in Northcote by allowing flood water to be channelled along the stream bed, rather than through private property. Having the water flow through an open channel provides much greater capacity than the older piped network. And, in this instance, it had the added benefit of keeping the parts of the older pipe in place, diverting a portion of the higher flood flows back into the pipe to provide even more flood capacity.” says Scott Speed, the Waterways Planning Manager at Auckland Council’s Healthy Waters.
Te Ara Awataha greenway network links existing and new reserves, providing areas for recreation and conservation. When not in flood, the returned stream bed will improve water quality and create habitat for manu (birds), ngāngara (insects) and tuna (eels) once more. The paths alongside the stream have rapidly become a valuable means of connection - both to local destinations and to nature.
Greenslade Reserve makes up another critical part of the greenway and stormwater infrastructure. The reserve was transformed last year to address flooding problems. This included a planted urban wetland and detention basin.
The reserve was designed to manage a one in 100-year flood event by detaining and slowing the release of water (able to handle approximately five Olympic size pools worth!). In late January, this proved critical.
At its peak, January’s downpour exceeded a one in 100-year event. Water overflowed into the street network, but the detention of 12 million litres of water on the sport field meant that flooding downstream was predominantly within the street network and damage to property was minimal compared to previous (lesser) events. When not in flood, Greenslade Reserve now provides a top-class sports field and recreational facility.
Kate Cumberpatch, Eke Panuku Priority Location Director - North, said: “The weather conditions were unprecedented, but we’re delighted that the new stormwater management infrastructure provided protection for the residents of Northcote! It did what it was designed to do, diverting and managing the extreme amounts of rainwater and preventing the extent of flooding we have seen in the past.”