Damaging winds 4/10/2015

[melja]

why does it have to be a land use change?
I would thought the dust would have come from the river beds in the foot hills/gorges
)

Some of it was, but most came from recently cultivated paddocks,i was watching an area 15kms away from me where there was heaps coming off a hill block recently done, its poor farming boarding on environmental vandalism and there's no excuse for it, direct drilling is a far better way to resow where you dont loss the soil to wind. Ive heard every time there's a big blow like this and soil is lost to the wind it takes 20-30 years to build the lost soil back again, but then the way the modern farming is today they push there soils so hard that there's so little carbon been returned back to the soil that its probably taking 100's of years.

New Zealand is so far behind other parts of the world when it comes to soil conservation

Have to agree with Richard on the environmental vandalism thing, huge amounts of land in the MacKenzie is being worked and put into grass just for a few months in spring to feed lambs and without irrigation it then turns into a barren dust bowl for the rest of the year, its just not sustainable in that environment and the rest of us get to enjoy there dust all summer.

[03Stormchaser]

Example of a paddock being stripped of its topsoil. This taken near Omaru, sent to me via facebook.

[Manukau heads obs]

alot of that topsoil will though fall downwind/on the port hills
so you could call it, top soil re distribution
(and that has occured for millions of years, even with the natural vegetation (tussock/low shrubs))

[Richard]

If you look through the strata layers on the Banks Peninsula you'll find they mainly clay deposits originating from glacial out wash during the ice age , not soil . The share volume of ice/water and gravels etc being shifted down from the alps meant that large areas of what is now the Canterbury Plains would have had no plant life on it including desert like sand hills on both the south sides of the Waimakariri and Rakaia rivers, it was a much different landscape to what we have today there for you cant compare what has occurred for millions of years to what occurred on Sunday especially when bring in large cultivating machinery into the equation.

[Razor]

alot of that topsoil will though fall downwind/on the port hills
so you could call it, top soil re distribution
(and that has occured for millions of years, even with the natural vegetation (tussock/low shrubs))

Fundamental error there, pre- people (ie until very recently) both the peninsula and plains were heavily forested.

[Orion]

Whatever.
There were no smiley faces in 1975 for the farmers who saw the soil blown away from their young grain-crops. It was catastrophic.

[Karliosis]

A little bit late, but I had some difficulty transferring data from kestrel to PC.
The pressure drop wasn't as rapid as I was hoping for, but none the less, the main pressure drop began around 8am at 1002hpa, and I recorded a minimum of 986.6hPa at 8:02pm. A 15 hpa drop in 12 hours.

I recorded a little bit of wind too, the max gust I got was 47.3hm/h, which is the strongest I have recorded in christchurch from my handheld. I think my previous max was around 42km/h, but I'm not 100% sure

Unfortunately I forgot to switch time for daylight savings, so the time on the graph is out by an hour.