In the aftermath of the Auckland floods, natural springs have been reactivated in parts of the region, including in Onehunga and around Eden Park.
Ross Roberts, the geotechnical and geological practice lead for Auckland Council, said he was examining surface level flooding in Onehunga on Thursday and noticed the springs.
The flooding had been caused by the reactivation of those springs due to the high groundwater, he said.
Tāmaki Makaurau was seeing the highest groundwater in the city since records began in 1997.
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Groundwater was about two-and-a-half metres higher than what Auckland would normally see even in the height of winter, he said.
Lines of springs had reactivated in Onehunga on Springs Rd and other parts of low-lying Auckland as a result.
Roberts said when it rained in Auckland, water could either flow over the surface, into the storm network or into the ground.
Because of all the volcanic rock in central Auckland, the water flowed into lava tubes.
Jason Dorday/Stuff
Flooding in Onehunga after torrential rain.
The intense downpours over the past week caused the water to rise and hit the surface, creating springs.
The water would eventually go back into the scene, just via a different route, he said.
Roberts said the springs were easy to identify once they occurred.
“For example I saw one yesterday coming out beneath the Dolphin Theatre on Spring St. It was popping up in their basement, coming out of the ground and flowing down the street.”
While groundwater would slowly go down over a period of one to two months, the peak would drop quickly and the springs should go away within the next few days, he said.
David White/Stuff
A field at Eden Park was flooded after heavy rain early on Wednesday.
Anyone impacted by springs needed to stay away from where water was flowing up from under, he said.
Roberts said water could erode concrete slabs underneath pavements, leaving voids. Silt coming from the springs indicated erosion is happening.
“It’s very important people are cautious and try not to take risks in these circumstances.”
People should look out for soft ground or cracks near any natural springs.
