State of emergency: Canterbury floods

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STATE OF EMERGENCY:

CANTERBURY FLOODS

Words by Heather Woods

In the days leading up to 30 and 31 May 2021, MetService had issued a red alert weather warning for much of Canterbury.

As growers and farmers did what they could to prepare crops, livestock and property, it was unclear just how extreme, dangerous and business-breaking the event would be. Then it started raining. The rivers rose rapidly, and what followed was an onslaught of water the like of which many had never seen. As banks burst and fields became lakes, local councils and Civil Defence Emergency Management worked under a ‘State of Emergency’ response helping communities cut off by flooded roads, and restoring key supply routes that had been closed off by broken bridges. Looking back on what was a wetand-wild few days, we spoke to growers from around the region who were on the front line.

Wind was the other factor, with vegetables like spring onions – which now have a nice bend to them – looking different from usual when they hit the supermarket shelf

Expecting more than a few drowned potatoes

In Southbridge, about 60km south of Christchurch central, Oakley’s Premium Fresh Vegetables was fortunate to only see around 70mm of rain fall on their main growing area. The ground coped well with the extra water. Their other two growing locations saw 130mm and 160mm respectively, so they’re expecting to find more than a few drowned potatoes in the crops still in the ground. Robin Oakley, founder and managing director of Oakley’s, said there will be a knock-on effect in the form of nutrient leaching and the effects of waterlogged soil in the crops still growing for winter and spring harvest. He would also expect a lot worse from another high-rainfall event in the short term. Robin considers them lucky that it wasn’t worse, and that those located by rivers that breached their banks likely experienced worse flooding across their properties.

The biggest impact was the effect on nutrients and fertiliser levels lost to the flood water that would have otherwise nourished the plants

Leaching is just as important as the water damage.

In the Lincoln area of Selwyn, Allen Lim at Jade Garden says they estimate that somewhere between 160mm and 200 millimetres of rain fell. With the soil pretty dry, that was a lot of water to deal with in such a short timeframe. Luckily, they didn’t see any infrastructure damage, but it certainly made the paddocks super muddy and difficult to get machinery into. But they were lucky in that there’s no river close by; they mostly saw ponding. For Jade Garden, though, this is the main growing season, so everything is currently in the ground. And while the volume of water was one issue to deal with, Allen is more concerned with leaching and their cap.

RAINFALL AT ALLEN LIM AT JADE GARDEN 160mm – 200mm

IN THE LINCOLN AREA OF SELWYN

RAINFALL AT OAKLEY’S PREMIUM FRESH VEGETABLES, 3 GROWING LOCATIONS

70MM SOUTHBRIDGE

130MM OTHER

160MM OTHER

The Maronan Bridge over the Hinds River. STACY SQUIRES / STUFF

The floods likely took nitrogen from the soil and he’s just hoping they won’t be held to their quotas, because they had zero control over the event and the fact that now they’ll need to reapply fertilisers if crops are to mature as normal. Otherwise, they (and other growers) will face the serious issue of no vegetables through winter. Wind was the other factor, with vegetables like spring onions – which now have a nice bend to them – looking different from usual when they hit the supermarket shelf. The problem is that consumers expect perfect looking vegetables down to colour and texture—despite them tasting exactly the same. Growers understand the issue well, but consumers rarely grasp this problem which is just as important as flood water damage itself. Down at Hewson Farms, Ross Hewson says the dry ground is most definitely waterlogged now. But the free-draining ground they’re on certainly helped the situation with surface water quickly draining away. For those closer to the rivers that wasn’t the case, and things are a bit of a mess. It was an incredible amount of water – around 145mm in the foothills, and the rivers just aren’t capable of dealing with that. The biggest impact was the effect on nutrients and fertiliser levels lost to the flood water that would have otherwise nourished the plants. Ross says simply, “We never need that much rain.” The good news, for Hewson Farms at least, is that they haven’t planted a lot of their vegetable crops yet.

It’s the largest rainfall Ross can ever remember, and he believes MetService was right to ‘red alert’ it; it was all they predicted, and possibly more

The flood came when most had either just harvested or not quite planted for the next year. So as much as this was an ‘out there’ weather event, it could have been a lot worse for them if crops had just gone in the ground. In fact, if it had happened any other time in the last six months it would have been devastating. It’s the largest rainfall Ross can ever remember, and he believes MetService was right to ‘red alert’ it; it was all they predicted, and possibly more.