Wednesday, March 15, 2017

Tempest toss’d

Last week, we were hit hard in Auckland by a storm dubbed the “Tasman Tempest”. The storm, which also affected Northland and the Coromandel, dumped a month or more of rain over only three days. It was a very big deal.

In Auckland, the average rainfall for March is 85.5mm (3.3661417 US inches), and last year March 10-12 Auckland had only 1.2mm of rain (pretty much none, in other words). This year, between March 10-12 Auckland received 101mm (about four inches) of rain—that’s more than 18% above the March average over just three days. That’s a lot of water.

There was widespread flooding all over the place. In Auckland, some of the worst flooding was in west Auckland, and on Sunday there was particularly bad flooding in New Lynn, where a sinkhole opened up. At one point Sunday some 2800 homes were without power due to a submerged substation, but power was restored within a few hours.

The weirdest thing to come out of the storm, however, was that we were told to cut back on our consumption of drinking water or we’d have to boil our water, and we were told it was Auckland’s biggest water crisis in 23 years. The reason is that the reservoirs that supply two-thirds of Auckland’s drinking water, located in the Hunua Ranges, had an extreme amount of silt stirred up, as might be expected: Because it was record rainfall, there was also record silt levels.

This was really weird. As I said on my personal Facebook:
Have to admit: I've never heard of having to save water because there was too MUCH rain! They want us to save 20L per person, which is about two buckets full. If we don't, and especially if there's more heavy rain, we'll get a boil water order. Nice. Their specific advice: No watering the garden (well, not needed, anyway…), No baths, Three-minute shorter showers, Avoid washing the car (not much point when it'll be in the rain…). Apparently they need a long period of dry weather for things to return to normal. So, we're supposed to conserve water and hope it DOESN'T rain. Very weird.
But what’s even weirder is how little sense this makes. As people who know much more about these things than I do pointed out to me, boiling water would only concentrate the silt for the consumer because water would boil off. Boiling is only necessary if there’s a contaminant of some sort—bacteria, viruses, etc.—that need to be killed. Watercare isn’t suggesting the water is contaminated, so the real threat would seem to be merely discoloured water, not something that would need to be boiled absent contamination.

Still, I’m no expert, of course, so it would be helpful if Watercare explained things more fully. However, they don’t even use social media, so we actually get very little information, which allows every armchair expert to weigh in, and without official expert information, we’re bound to be confused. And, in the 21 years I’ve lived in New Zealand, most of that in Auckland, I’ve never been told to conserve water before.

Still, water conservation request notwithstanding, we faired quite well. While there was some surface flooding in our yard, and rain poured over the gutters at times, we weren’t damaged in any way, nor were we flooded. Two days later, the grass is already noticeably starting enjoying the ideal growing conditions, even in those areas that had surface flooding.

So, the Tasman Tempest was very, very bad for some people, kind of bad for a lot more, and an inconvenience for the rest. Pretty much like any big storm can be, except that most don’t lead to requests to conserve water. There’s a first time for everything, I guess.

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