Designing for Climate Change II

In the first post I wrote about stabilising the stream banks and feeding out pollarded willows to the goats. I also mentioned the casuarina and cabbage trees planted in the riparian corridor. Here is an image of them.

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Much of this work designing for climate change came after the 2015 Whanganui floods. Here is a picture of the neighbours place the day after.

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This is the neighbour on the other side. Lots of dead sheep.

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But truth be told we had started our work before the June flood. As a matter of fact, just two days before the storm hit the Whanganui region I was finishing up a French drain around our home with the help of my daughter.

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Because it was mid-June we were also preparing our garlic for planting later that night.

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At least someone enjoyed the weather.

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Our calf, Heidi, weathered the storm down in the valley. Note the culvert that I am clearing in the image below and keep it in mind when viewing the image that follows.

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The willow in the foreground gives you the relative location of the culvert, which you can’t even see due to the extensive plantings along the stream following fencing off the riparian corridor.

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But this post should really be about the hillsides, where slips occur, and how to reduce the risks of future slipping. We have planted over 100 3-metre poplar poles that come from the regional government. They should be soaked for a week before planting 700 mm deep in mid-winter.

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We locate them mostly in the valleys where water is concentrated during storms.

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After three winters of planting, we are now up to the upper slopes. On the side of the farm with the goats we use tree guards and on the side with the kune kune pigs we do not use them.

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But I am told that it takes seven years for the roots of poplars to grow broad enough to hold the hillsides against slips, which raises the question: what to do during the intermediate years to prevent slips from taking out the poplars? Our answer has been targeted drainage.

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There are certain areas where we can capture concentrated surface runoff on the hillsides and leapfrog it over the most vulnerable slopes. This is not ideal, but may be a reality in a world of increasing extreme weather events.

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In summer we take the pipes down and store them under trees out of direct sunlight. This preserves the plastic pipes and retains water high on the landscape during the dry season. It is an expensive measure but part of what I call Triage Permaculture. Seasonally installing and dis-installing the pipes is part of what I call four-dimensional design management.

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Sadly, we’ve also had a neighbour dumping water onto our land illegally, which has caused an additional slip.

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Because they will not take responsibility for their own water as prescribed under The Building Act, I have had to put in a drain and a sump (made from a flower pot) and more plastic pipe to redirect the water away from the vulnerable area.

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We’ve also put in a surface drain to draw stormwater away from the top of the slip, which is dangerously close to a fence and a major farm track.

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This has all been a massive effort requiring tens of thousands of dollars and hundreds of hours labour. But at the end of the day, if I want my children to inherit a resilient farm there really is no other option.

 

Peace, Estwing

2 thoughts on “Designing for Climate Change II”

  1. We lived up the awa for several years and put in alot of poplar poles on steep slopes. We made sure that we would be able to regularly top them before they got too large (used them for stock feed) as when it was windy, they would rock alot if not sheltered and the roots would pull up large clumps of soil. Neighbour across the river actually felled many of his large poplars because of this, and all the leaves which carpeted the ground in the autumn killing the grass. I guess you are aware of side effects of polars.

    1. Thanks Ann. We have planted mostly Veronese based on the advice from Horizons. There are so many cultivars of poplars I have to rely on HRC to give the best advice for our conditions. We have large poplars on our land and adjacent properties with no signs of instability – on the contrary, they’ve held the soil during slips nearby.

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