Most major rivers in New Zealand have a history of destructive floods, and European settlers soon discovered that floods were a recurring menace. Wellington’s first settlers arrived at Petone in January 1840, intending to farm the broad Hutt Valley. Less than two months after they arrived, the Hutt River overflowed, inundating their huts and tents. After several more floods during the next few months, most of the settlers abandoned the Hutt Valley and moved to Thorndon, now part of central Wellington.
In Christchurch, settlers unwittingly chose a site for the city that was part of the constantly shifting channels of the Waimakariri River.
Blenheim – ‘Beaver Town’
Blenheim was dubbed ‘Beaver Town’ or ‘The Beaver’ by early surveyors – like a beaver colony built in midstream, it was often completely swamped by the meandering Ōpawa River. The river also acted as an overflow channel for flood water from the Wairau River. During one period in 1893, the local newspaper, the Daily Times, noted:
Again the town has been inundated with Opawa back-water, and this time to a greater height than has been the case during winter. We have now had nine floods in 11 weeks, each of them being of sufficient size to entirely suspend business operations for two days. 1
Central Otago floods, 1863
In 1863, prospectors swarmed over the mountains of Central Otago, camping along the streams and rivers where there was gold. The winter that year was severe, with thick snow blanketing the mountains. In July, warm rain deluged the region for six days, and rain and melted snow poured into the rivers.
Between 25 and 27 July, rivers swelled to disastrous levels. During a single night the tributaries of the Molyneux (now the Clutha) – the Shotover, Kawarau and Arrow rivers – rose by 6 to 10 metres. The floods overwhelmed dozens of miners asleep in tents and makeshift huts on the river banks beside their claims, or even on terraces well above normal river levels. Eight huts disappeared from a beach in the Arrow Gorge, and by morning, only one tent of many was left on a terrace opposite the Arrow township. In the upper Shotover River the torrent undermined a terrace, and a hut where 15 men were living collapsed into the river, and 12 drowned.
The sodden mountains gave way in landslides that sometimes blocked the valley floors. Weeks earlier, a landslide had dammed a stream running into the Shotover River at Sand Hills near Māori Point. Swollen by heavy rain, the stream burst through the barrier on 26 July and overwhelmed a camp, killing 12 miners.
On the Arrow River, a landslide dam broke, releasing a wall of water that swirled through the lower areas of Arrowtown, sweeping away buildings and burying everything beneath several metres of gravel. Most miners escaped to high ground, but many lost all their belongings and equipment. By the end of August, more than 100 lives had been lost because of the Central Otago floods.
Clutha floods, 1878
Although the Central Otago floods of 1863 resulted in more deaths, the Clutha River floods of September and October 1878 caused the worst damage. Heavy rain and melting snow in the headwaters of Lake Wānaka produced floods that lasted for three weeks, inundating settlements and demolishing dozens of bridges along the whole length of the river. A 1938 account described the Clutha in flood:
[i]ts angry surface [was] strewed with dead horses and cattle, houses, bridges, furniture, timber and farmstacks. Some days the spring sun shone with a ghastly pleasantry on the devastated towns, while 100 miles away more heavy rain on the mountains was preparing still greater strength for the flood. 2