The rains came fast and hit hard. Downpours from ex-tropical cyclone Debbie battered the Bay of Plenty – and was more than the small town of Edgecumbe could bear.
After days of straining against rising river waters, the concrete floodwall separating the Rangitāiki River from the town leaked and eventually burst, unleashing cascades of water.
At around 8:30 on the morning of April 6, 2017, those living in the town were told to leave their homes to seek higher ground.
New Zealand's history is riddled with severe floods – around 100 over the past 60 years; nine in the past 14 months alone – which have washed through townships, displacing families and entire communities.
Were there signs floods were going to happen? How does climate change play into how predictable, and severe, future floods will be?
The timeline of events leading up to April 6 seem straightforward: heavy rain, swelling river, stopbank burst. But according to the late Sir Michael Cullen, who led a 2017 independent review of the flood, the situation was "complex".
Floods are caused one of three main ways: rain or snow melt can cause rivers to swell and overflow, also called a fluvial flood; rain can hammer concrete surfaces and overwhelm stormwater systems, pluvial flooding; ocean waters can sweep up high onto land, coastal flooding.
Three days before the Edgecumbe flood, MetService had issued a warning for heavy rain, culminating in predictions of 200 to 350mm of rain in less than two days. The other factor at play was that the previous month had been very wet as well, meaning soils were already soaked from high rainfall.
Heavy rain and wet soil combined to cause the Whakatāne and Rangitāiki Rivers to swell, with the Rangitāiki river about 20 per cent fuller than the previous 2004 flood.
The weather signs were there, how the region dealt with its consequences came down to its flood management plan.
Edgecumbe's main lines of defence were the nearby Matahina dam, which could store some of the floodwaters if water was drained out of the Matahina Lake; Reid's floodway, which would divert water away from the city; and various floodwalls along the river, which should have held the waters back.
The floodway was outdated and in the process of years-long upgrade, including widening it to accommodate more water. Design issues, landowner negotiations and dodgy modelling of its capabilities all contributed to delays in completing the floodway by 2014. If it had been, it's likely there would have been less pressure on Edgecumbe's last line of defence: its floodwalls.
Twenty minutes before it burst, residents noticed water seeping from the wall. That seep turned into a fountain up to a metre tall spurting from the concrete. One fountain turned into several. Finally, the wall cracked open "like two gates" unleashing water upon the town.
Not all floods can be traced back to something as dramatic as a concrete barrier failing. Northland's 2020 flood saw rivers and streams swell but water also collecting on concrete surfaces and in low lying areas. After months of droughts, more than 200mm of rain fell on the region, causing slips that closed the main highways and water to pool and eventually inundate homes.
Both floods had emotional, legal and economic follow-ons. Years later, school children in Edgecumbe would cower under tables when it rained heavily. Other people would speak about how traumatic and lonely the past few years had been.
Homes would be left uninhabitable, some caked in mud and debris; others were completely washed away or foundations destroyed. Insurance claims for lost or damaged homes and belongings totalled in excess of $91 million in Edgecumbe and $37m in Northland.
Various factors contribute to the flood risk of a home, and according to Tower Insurance, these can range from the number of floors to the building materials and flow of water.
New technology developed with analysis from Risk Management Solutions (RMS) and brought to New Zealand by Tower gives homeowners a much clearer picture of the individual flood risk of a property, says Tower CEO Blair Turnbull.
"The benefit of using the RMS model is that it is so detailed that neighbouring properties can have very different ratings, depending on the camber of their land, whether they have a flood wall, and other factors."
New Zealand has been rated one of the worst countries in the world for natural disaster risk; this modelling helps homeowners and potential owners to make the best decisions for themselves. Each customer is given a low, medium, high or very high rating for flood risk.
"Ninety per cent of Kiwis told us that access to flood risk data about a house they are looking to buy may change their thinking about the property in some way," says Turnbull. "We also know that only one in three Kiwis feel very confident they have the right level of insurance for their current house to cover the risk of flooding by waterways and rainfall."
To learn more about your property's flood risk rating, get started by clicking here.