Southland floods, 1984
In late January 1984, devastating floods struck Invercargill and other parts of Southland. The cause was a combination of north-westerly rain in the mountain headwaters of Southland rivers, and a slow-moving southerly front that dumped heavy rain over the lowlands. Steady rain on 26 January – a record one-day total of 84.8 millimetres – had by 9 p.m. caused extensive surface flooding in the streets of Invercargill, Riverton, Ōtautau and Bluff. Waterways soon overflowed, and by 4 a.m. a state of emergency had been declared in Invercargill. By morning many streets, houses, shops and factories were under water, and streams were sending torrents of water through Invercargill. Levels rose still further as high tide prevented flood water draining into the Invercargill estuary. By mid-morning of 27 January, the state of emergency included all of Southland. The rain had stopped by noon, but the rivers continued to rise.
Army and air force personnel were dispatched south to aid rescue efforts. An estimated 5,000 people abandoned their homes, and helicopters lifted dozens of people from rooftops. Roads and railway lines were submerged, cutting off the region from the rest of New Zealand. Water up to 3 metres deep flooded Invercargill airport, partly submerging 10 light aeroplanes.
It would be a week before most people could return to their homes, and several weeks before the state of emergency was lifted. When the flood receded, extensive damage was revealed: at least 1,200 homes were uninhabitable, and residents eventually discarded more than 5,000 tonnes of ruined personal possessions. Hundreds of flooded cars had been abandoned. No human lives were lost, but livestock losses were heavy – more than 12,000 sheep, 330 pigs, 100 cattle and 75 deer were drowned. A relief appeal raised more than $3 million, while tens of millions of dollars were paid out in insurance claims.
Cyclone Bola, March 1988
One of the most damaging cyclones to have hit New Zealand in the last two centuries is Cyclone Bola, which struck the Hawke’s Bay and Gisborne–East Cape region in March 1988. The former tropical cyclone slowed as it moved over the area, resulting in over three days of torrential rain. Worst affected was the hill country inland from Gisborne, where strong winds forced warm moist air up and over the hills, augmenting the rainfall from the storm itself. In some places, over 900 millimetres of rain fell in 72 hours, and one locality had 514 millimetres in 24 hours.
A ruined harvest
Flooding from Cyclone Bola had a devastating effect on horticulture in the East Coast region. The damaged crops included 3,000 tonnes of grapes, 1,300 tonnes of squash, 7,000 tonnes of sweetcorn, 13,500 tonnes of tomatoes, and several million dollars in vegetables for the local market. Large amounts of horticultural produce were swept into the sea – fishing boats were dredging fruit from the sea floor in their nets for several months after the storm.
The ensuing floods overwhelmed river stopbanks, damaged houses, swept away bridges and sections of roads and railway lines, and destroyed parts of Gisborne’s main water-supply pipeline. Three people died in a car that was swept away by flood waters, and thousands were evacuated from their homes – 3,000 in Gisborne, 300 in Wairoa, and 400 at Te Karaka.
The downpours triggered innumerable landslides on the region’s hillside pastures. Some farmers lost 30% of their grazing area, with landslide scars taking decades to heal. Huge quantities of sediment were dumped into the flood waters. One 11,000-hectare catchment deposited a million tonnes of sediment into the Waipāoa River. Thick sediment from the ebbing floods smothered pastures, orchards, and crops ready for harvest. Cyclone Bola was estimated to have cost $90 million in losses to horticulture and farming, and the cost to the taxpayer was around $112 million.