Saturday, March 29, 2014

Restoration work

When we first stepped foot on our property, close to seven years ago, we naturally radiated towards the flattest land. It was where the water ran off the main street, and the two gullies on our property drained to. Only at the time, it was at the tail-end of a drought, so it looked like a dry sand bed.

Water entering property, about a metre wide

Thankfully, it has rained a lot since then, so we've gotten to know our dry creek bed rather well in the wet too. Above you can see the water run-off, 24 hours after a lot of rain recently. This water is coming from our neighbours land. They have a concrete culvert, cutting across the creek bed so they can drive to their house. Being concrete however, it creates a lot of turbulence and velocity when the water flows through it.

If the rainfall is steady, like it was a few days ago, it will drop silt in a sheet (above) where the water drains away. In heavy rain though, the water can cut up the creek bed and even eat into the slopes at the sides. We knew it needed some restoration work, if we are to return stability to this particular area of the property.

Soft landscaping

So whenever we had tree branches or lantana to pull out, we placed them across the creek bed, to act as a silt trap. Above you can see a thicket we constructed, which has been there for about twelve months or so. Grass has grown through it in the dry weather, and then it gets pushed over when the water passes through in the wet. The grass dies, but creates even more matting to catch silt with.

We had some pretty bad erosion from the flood in 2011, it created a deep saucer that kept scouring deeper whenever we had more rain. Since placing the thicket here however, the deep saucer has gradually filled with silt. What's even more interesting, is seeing how the water flow has changed through our property.

Reduced water flow

This is water flowing after the thicket. It has a reduced flow compared to the sped of what was entering. You can also see how the width of the water has changed. It went from about a metres width, when the water first entered the property, to 30 centimeters now. Grass is also able to survive closer to the water, because its not being pushed over and starved of sunlight. This strategy has reduced erosion throughout the creek bed.

Staying put

After the water has passed through yet another thicket we constructed, it has virtually no flow at all. This water has been retained 24 hours after rainfall has ceased. These are very small modifications we've made, but over the seasons it gradually changes how the water flows.

We will continue with this work, because it's important to help drought proof and reduce erosion on our property. In the full circle of things, it will also help lower bush fire risks. By taking the dead wood and strategically placing it to capture and retain water now, it will help to grow plants less likely to ignite in a fire. Less likely, doesn't mean bullet proof, but its still a step towards not living in a tinder box either.

Bare patch where lantana formerly was

In other restoration work, we've (er, David) cleared some weedy lantana, to make way for a native plant I finally managed to track down. It's called Bursaria spinosa, and shares similar properties to the lantana. There is a special reason for wanting this.

When we first stepped foot on our property, all those years ago, and stood in our dry creek bed, we suddenly noticed we weren't alone. There was a chorus of birds, calling to one another; darting from lantana bush to lantana bush. They were tiny flock birds: finches, wrens, robins and the like. We fell in love with this place from that moment on.

So when it came to removing weedy lantana bush, which is mandatory under law, I wanted to give these remarkable flock birds something similar to nest in. I could never imagine evicting them from their homes, just because we decided to purchase the land they live on. You have to nurture a love affair, not erode it with possession.

It's one of our greatest joys, doing this slow restoration work. Every season it changes a little more.


  1. I love Bursaria. We have it here. Not much originally, but it has self-seeded. The flowers are beautifully perfumed and the butterflies love it, too.

    Interesting restoration work, too. Does the water eventually exit the property, or have you managed to soak it in?

    1. Nice to hear of another recommendation for Bursaria. I'd never heard of it, until I started looking for a substitute for lantana (ie: another prickly shrub). We do get quite a lot of butterflies, so I think Bursaria will fit in quite well here. We just had a lovely run of rain so I'm waiting for it to dry out before I start planting.

      The water does eventually exit the property, and we'd love to dam it off. Alas, no money for earthworks, so we've recently purchased some vetiver grass and plan to grow it at the property boundary. As long as the frost doesn't kill it off, it should build a dam wall behind it every time the storm water run-off, drops silt. At least that's the theory. We hope to get the vetiver in soon. Just need to get the brush cutter out first, to access the area. :)

  2. This kind of work is the kind I find the most interesting. I know a lot about growing plants and working with soil but not much about earthworks which I guess this qualifies as. I think this knowledge will become much more important in our world as our environment changes-we need to learn to adapt.

    You said your grass dies out from laying flat. Nothing-and I mean NOTHING will kill our grass off. Even the sand that the county uses to keep the roads safe during our ice season ends up on our lawn and that doesn't smother it. We have opposite problems than you but its good to know how yours reacts.

    1. It's definitely an area of interest for us too, as we need to employ earthworks, without employing earth moving equipment. We've seen how the storm water run-off drops silt (and large amounts of it) so we just need to design something to trap the run-off.

      There are all sorts of methods you can employ, from gabion walls, zuni bowls, and tree trunks tied together - to the method we prefer, being silt traps with whatever plant materials are to hand. The vetiver grass we recently purchased, is what they use to make rice paddy fields. So they can withstand some inundation for a period of time, and they catch silt so you end up with a solid wall over time.

      I imagine the grass you have, has evolved to withstand the elements in your area. It sounds like you may have boggy problems, if you have the opposite problem to us. We just recently experienced some extended wet weather, and we've noticed some boggy patches under the new driveway.

      The grid pavers are doing their job, retaining water, so lower down on the natural earth (that used to drain in the wet) we now have mush. It's a new problem for us, but I guess also an opportunity to harvest moisture for longer periods of time. We're thinking the grid pavers are required, and a French drain underneath them. This should stop it from becoming too boggy, when we come off the driveway and manouvre the vehicles.

      It's nice to have wet problems for a change, lol.

  3. I am sure that having wet problems once in awhile is great for you! Yes, we do have boggy problems at this time of year when our snow melts, the earth unfreezes and it rains all at once but there is one area in particular that I see it as more consistent throughout the rainy season and that where water runs off our driveway. I am not concerned about it as a genuine problem so much as wondering how I can take advantage of the area. Something non edible and perennial (worried about what is in the run off). I also thought to try to plant something akin to reeds but I have not looked into it yet-its likely not a perennial in our area but it would be ideal to clean the water as it continues to its next destination.
    Your new ideas for the run off form the pavers sounds good.

  4. I'm always amazed when we manage to make water seep in the ground (as opposed to running away) we get natural reeds occurring voluntarily. We don't plant seeds, they just spring up when we make the area soggy enough for long enough. I wonder if you are able to make a small saucer in this area to collect water, as opposed to it running away after the thaw - and if reeds will occur naturally for you too?

    In my experimentation, I have found when changing the environmental conditions, indigenous to the area plants, always emerge voluntarily. It would be an interesting experiment. :)


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