16 May 2015

Just how wet did Wellington get?

10:18 am on 16 May 2015

New figures show just how sodden the Wellington region became this week.

MetService's rain radar shows the weather sweeping across Wellington at 10pm on Thursday.

MetService's rain radar shows the weather sweeping across Wellington at 10pm on Thursday. Photo: MetService

Parts of the region had more rainfall in one day during Thursday's deluge than would normally be expected for all of May.

Figures released by the Greater Wellington Regional Council have officially recorded record rainfall and what are considered to be one-in-50-year events in some places.

View a gallery of images from Thursday's torrential rain and flooding

Here are some key figures from the damaging storm:

  • Rain gauges at MacKay's Crossing, Battle Hill and Tawa Pool recorded more rain in one day than the rainfall normally expected during the entire month of May.
  • MacKay's Crossing received a total of 145mm over 24 hours, which is a one-in-40 year event.
  • In some places on the Kapiti Coast, river levels were the highest since the floods of 1998.
  • The 24-hour rainfall total at Battle Hill near Pauatahanui was equivalent to a one-in-50-year event.
  • The Porirua Stream had the largest flow since 1980.
  • In the Hutt Valley, 42mm of rain was recorded in Avalon in just one hour, which is estimated to be in excess of a one-in-50 year event.

Heavy rain started on the Kapiti Coast in the early hours of Thursday, with 145mm recorded over 24 hours at MacKay's Crossing. Waikanae received 102mm of rain in 24 hours - with a particularly intense burst recorded at Te Hapua Rd, south of Te Horo Beach.

The Waikanae River rose to a peak flow of 270 cubic metres per second, which was the third largest flow recorded since 1975 (behind January 2005 and October 1998).

The Wharemauku Stream - which breached its banks, causing the evacuation of several homes - reached a level almost as high as that recorded during October 1998.

Paraparaumu resident Justin Patterson moves his furniture.

Paraparaumu resident Justin Patterson moves his furniture after his home flooded on Thursday. Photo: RNZ / Gareth Thomas

A large sink hole which opened up in Matatua Road, Raumati.

A large sink-hole opened up on Matatua Road, Raumati, after Thursday's storm. Photo: RNZ / Charlotte Gendall

In Porirua, the Horokiri Stream rose rapidly and reached its highest flow since 2003.

The Porirua Stream rose to a peak flow of 66 cubic metres per second, which was the third largest flow since the floods of 1976 and the largest since 1980.

The rain gauge at Tawa Pool recorded 62mm of rain in two hours - an intensity expected just once every 40 years.

The Hutt Valley was also severely hit by Thursday's storm - with 42mm of rain recorded in a single hour in Avalon. According to the council, that's worse than a one-in-50-year event.

Among other parts of the region to have had more rainfall in a day than they would normally get in the entire month of May were MacKay's Crossing, Battle Hill and Tawa Pool, which recorded - in order - 145mm, 144mm and 115mm.

Source: Greater Wellington Regional Council

Melling bridge under pass

Flooding at the Melling Bridge underpass on State Highway 2. Photo: George Bignell

Flooding in Porirua this afternoon.

A car stuck in flooding in Porirua on Thursday. Photo: Kate Gudsell / RNZ

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