Nelson and Tasman Floods

Floods have, and will continue to have, a significant impact on the city of Nelson, particularly the Maitai / Mahitahi River, the Brook or York Streams,  and more widely across the Tasman region.  Flooding has wrought havoc on property, and resulted in injury and even death to residents.

Nelson Flooding

From the time of Pakeha settlement, and the surveying and clearing and development of the land, the Maitai / Mahitahi catchment streams and river has flooded several times: 1844, 1879, 1904, 1908, 1910, 1916, 1918, 1960s and significantly, in 1970.

As early as 1913, land clearance was identified as a cause of flooding. A letter to the Nelson Evening Mail on 10 March 1913 from H G Kingsland addresses the “great question of deforestation”.  Prior to the arrival of European settlers, most of the Maitai Valley (and indeed most of Nelson) would have been covered in toe-toe, fern and manuka, with dense stands of podocarp forest on the flats. What is now known as “The Wood”, was once about 60 hectares of native beech and kahikatea trees. This area provided the early settlers with timber for buildings and firewood, though sadly even this does not remain as kahikatea proved not to be a durable timber.

Clearing the land, residential building, wetland drainage, and reclamation has necessitated the many modifications on the streams to mitigate flooding.

The Flood and slips of 2011

On Tuesday 13 December, 2011, as people began to plan for summer, it began to rain and didn't stop until Thursday 15 December. The torrential rain was caused by a trough stalled between a low in the Tasman Sea and a high to the east of New Zealand. It was a one in 500 year downpour for Tākaka and a one in 250 year event in Nelson.¹  A "pipeline" of rain had developed as subtropical moisture barreled in from the north Tasman Sea.²

The disaster was the worst the region had seen for decades. A third of Tākaka's normal annual rainfall (674mm) fell over two days. The coastal strip from Brightwater to north of Hira, including the hills behind Nelson also suffered from the deluge. At Richmond, 280mm was measured over 48 hours - more than a quarter of Richmond's normal annual rainfall.³

A state of emergency was declared on the evening of Wednesday 14 December following a day of heavy rain. The Matai / Mahitahi River rose, flooding its banks, precautionary sandbags were laid and several roads were closed.⁴  Hillsides became waterlogged and slipped - tons of mud, water and debris poured across farmland, roads and into houses.⁵

By 15 December, the band of intense weather began to move away from Nelson and the region began to assess the damage. There were multiple road closures and damaged properties.  Hundreds of people were evacuated from their homes. Residents in Nelson's Wood area were evacuated as police feared a slipping hillside might collapse onto their houses.⁶ An apartment building on Wakefield Quay was evacuated due to a slip behind the building.⁷  About 30 homes above a major slip in Rocks Road were evacuated as a precautionary measure.⁸

State Highway 6 around Nelson's waterfront was closed, with peak traffic gridlocked on the main route between Richmond and Nelson.⁹ A slip put the city's water supply at risk and contractors worked furiously to stabilise the Maitai pipeline just below the Maitai Dam.¹⁰

Cable Bay/ Rotokura was cut off for several days with many slips along the only road in to the small community. Network Tasman linesmen were flown in to restore power and supplies were taken in by helicopter.¹¹

Groundwater on the Waimea Plains rose to unprecedented levels and large parts of Moturoa / Rabbit Island remained flooded five weeks later.¹²

In Golden Bay / Mohua the year was bookended by floods. In January 2011, floods described as the worst in 169 years, devastated parts of Golden Bay /Mohua, causing more than 6 million in damage. The swollen Anatoki and Aorere rivers raged through homes, washed stock downstream, destroyed bridges and damaged roads and power lines.¹³

In the December event, the rainfall was mainly coastal, and the lower country, unaccustomed to such heavy rain, became saturated and bore the brunt of the damage.¹⁴  People in Ligar Bay fled to higher ground as a wave of trees, mud, rocks and water thundered down the valley.¹⁵   Mike Robertson's 430-hectare Wainui Bay dairy farm was ravaged by 12 landslides which covered his paddocks, trapped 300 cows and left the land covered in up to five metres of mud. He expected it would take about a year to clean up the farm.¹⁶

Collingwood was cut off by a large slip on Birds Hill, and in Pōhara up to 30 Pōhara homes were damaged by a dam bursting.¹⁷ The winding road between Wainui Bay and Tōtaranui was blocked by slips and remained closed through the summer.¹⁸  In February, the New Zealand Transport Agency agreed to provide 2 million for the road's restoration as part of its Golden Bay / Mohua recovery package.¹⁹

It was considered incredible that nobody died in the disaster, but there were a few close calls.  Ian Watts (77) was carried several hundred metres from his Clifton property when a deluge of water from nearby Ellis Creek tore through his house and carried him out onto his paddock. He suffered only a broken finger and wound to his hand.²⁰  A huge rock dislodged from the hillside above Rocks Road slammed into the side of a four wheel drive vehicle as the driver waited in a queue of traffic - he was unhurt.²¹

By Saturday, 17 December, inspections were underway on more than 300 homes throughout Nelson/Tasman and nearly 140 properties were issued with red or yellow stickers.²²  In February 2012, about 70 families were still unable to return to their homes. It was estimated that flood repairs and recovery for the whole region would cost around $40 million: about $15 million for Nelson and close to $25 million for Tasman. It was expected that recovery projects would take up to 10 years to complete, with the costs spread across that period.²³

Forty five section 124 (red or yellow sticker) notices remained on properties in Nelson - mainly around Haven Road, Tāhunanui Drive and Princes Drive by the beginning of March 2012.²⁴

Retired Nelson city engineer, Mac Crampton, said the 2011 flood in Nelson was less severe than a flood in September 1970 when two women died²⁵ and dozens of Nelson homes were evacuated in what was then described as the worst flooding for almost 40 years.²⁶ This flood had a significant impact on Nelson City Council infrastructure, taking out many bridges and roads. Despite some Government financial support, other capital projects, such as plans for new Library and Museum buildings, were delayed for many years.

There have been a number of major flood  events in the Nelson-Tasman region over the years, with severe flooding in 2010, 1986, 1983, 1970, 1957, 1947, 1929, 1904, 1895 - many of these causing severe slips and damage to equal the event of 2011. Search NIWA's historic weather events catalogue for information about floods in the region.  Key information sources are also listed as "Further sources" below.  

Follow the link below for video images of the December 2011 flood (scroll further down page for more images): Golden Bay flooding: amazement no one killed (2011, December 16) Stuff.co.nz

2012

Floods in February 2018

In February 2018 Nelson and Tasman were hit by ex-Cyclone Fehi and a few weeks later, Cyclone Gita. Fehi coincided with a king tide and wreaked havoc along the Nelson and Tasman coastline and damaged heritage buildings and structures - for example the Boathouse, Boatshed and Cawthron's posts and chain along Wakefield Quay. Cyclone Gita severely damaged infrastructure in the Tasman District, particularly the Tākaka Hill Road, Cobb Valley bridge and Mārahau. New reports documented the event:

Ex-cyclone Fehi - February 8 2018:

• Gooch, C (2018, February 5) Ex-cyclone Fehi leaves lasting impression on Glenduan Nelson Mail on Stuff
• Neal, T. (2018. February 2) Nelson storm damage prompts tough conversations. Radio New Zealand
• Sivignon, C (2018, March 3) McKee campground near Nelson may close permanently. Nelson Mail on Stuff

Cyclone Gita -  February 20/21 2018:

• Cyclone Gita: Flooding highest we've ever seen, say frightened Nelson Tasman locals (2018, February 21) New Zealand Herald
• Cyclone Gita: Whole trees, mud blanketing parts of Nelson, Tasman regions (2018, February 21) New Zealand Herald
• Gita: Clean-up may take 'longer than a year'(2018, February 22) Radio New Zealand
• Rethink for forestry after 'disaster' at Marahau (2018, February 28) Radio New Zealand
• Hindmarsh, N & Gee, S. (2018, February 21) Gita: Massive task ahead to re-open slip-damaged Takaka Hill highway. Nelson Mail on Stuff

2018

Floods in July 2021 

High winds and heavy rain swept across the top of the South Island and lower North Island from Friday 16th to Sunday 18th of July 2021. North Westland, Buller and parts of Marlborough had the worst weather with many homes and properties damaged, but Nelson and Tasman also had a massive amount of rain fall over two days. A rain gauge in Golden Bay / Mohua (Anatoki at Paradise) collected 649mm of rain over 48 hrs. 

Strong gusts of wind damaged trees and powerlines in Nelson and Tasman. The residents of the Owen River area and Upper Moutere lost their power and fallen branches and trees also blocked the road between Hira and Havelock. 

State highways into and out of the region were closed due to flooding, rockfalls, mud, and debris. Tākaka, Collingwood and Murchison townships were cut off and many other roads such as Motupiko to Kōhatu were closed as well. Heavy rain high in the hills contributed to high river levels.  The Motueka River bursts its banks near the outlet into Tasman Bay / Te Tai-o-Aorere, and homes near the Ruiwaka River had to be evacuated when it too became dangerously high. Livestock, orchards, and paddocks were damaged by the water.

Other impacts of the storm included the pathway along Rocks Road between Tāhunanui Beach and Port Nelson being damaged by strong sea swells. Walking and biking tracks such as the Heaphy Track also suffered storm damage and needed to be closed for repairs. 

Read more about the July 2021 storms:

• Newman, T. (2021, July 17). Nelson floods: Worst of rain over but rivers slow to recede Nelson Mail on Stuff.
• Wild weather: Homes evacuated, roads closed across top of South Island (2021, July 17). Radio New Zealand.  

2021

Last update added July 27,2021

Story by: Joy Stephens