One-in-a-150-year flood event
This aerial photograph shows part of the flooded area. Joan Whiting Rest Home is in the foreground. Photo: Supplied.
The flood that followed the drought-breaking torrential rain over 27 and 28 December is being called a one-in-150-year event, and the fact that no one lost their life “miraculous”.
Barely a month ago, the Aorere River’s flow had dropped to around 8 cumecs (cubic metres per second), but over the night of 27/28 December it was scoured by the highest river level since records began in 1977, an 8.2m-high flood that peaked at a phenomenal 3,500 cumecs per second—roughly equivalent to the flow if every dam on the Waitaki released its flood gates at once. The Aorere’s previous high was 7.7m in 1985.
The river, which dramatically altered its course during and after the event, flooded 35 homes and outbuilding, some up to 500m from its usual banks. On TV One’s News, Merv Solly related how he was forced to abandon his house and climb into the stock crate of one of his trucks to escape the rising flood level. The force washed farm stock, fencing and a caravan downstream, submerged vehicles, and damaged roading and other infrastructure. Dalls Creek at Rockville lost 40 metres of road. Trampers were stranded, and over 20 campers in the valley lost equipment.
The torrent destroyed the James Road bridge, completely isolating farmers Graham and Jenny Pomeroy. Graham said that at the height of the flood the river sounded like a big jet plane.
“Amongst the terrific noise you could still hear the big boulders getting washed down, rolling and clonking together. The river was full of huge native trees getting swept down. It was an awesome experience and very humbling to see.” The water swept away 75 nearby heifers belonging to Steve Garrett, and also ripped away the century-old Salisbury footbridge at the beginning of Quartz Ranges Rd. This is unlikely to be replaced.
Bainham and Rockville were without power for a day, leaving some farmers unable to milk their herds, and many who could were unable to get milk out of the valley due to blocked roads.
Compared to the Aorere Valley, Takaka and its environs was spared extensive damage due to little wind and a low tide when rivers peaked, but in that same night, the Anatoki River was measured at a height of 5.1m (previous record 5.0m).
Probably the worst-affected property in the central Bay was Bencarri Nature Park, owned by Leith Dixon and husband Mike.
“The water was hitting the swing bridge that’s normally four meters above the river and all it needed was a tree to come down and it would have smashed it. It was pretty dramatic,” said Leith.
Other cattle were reportedly lost at Wainui, but overall, farmers have reported that numbers of dead animals have been much lower than first thought. Beasts are still being found and wandering in from the bush. In the Aorere, a tree had to be felled to rescue a live cow stuck in its canopy.
Rainfall levels for the relevant period were recorded as moderately high in coastal Golden Bay (between 100 and 150mm in many places), and 174mm at Rockville on flood day. Over 400mm of rain fell at Paradise Peak between Bainham and Anatoki, while DOC’s unofficial rain reader at Perry Saddle recorded 1200mm for the two days over the flood.
Figures suggest rainfall in some parts of the Aorere was close to NZ’s rain day record of 647mm recorded at Rapid Creek, near Hokitika, on 22 Jan 1994.
Flood coverage: Ina Holst, Gerard Hindmarsh and Maria Polglase
