Sunday, 25 September 2011

How to: Install a dry creek bed

Heavy rain revealed a serious weakness in the design of our new garden, which has raised beds separated by 'ground level' paths. Whenever we got a downpour, water built up in all the paths and had nowhere to go (except into our shoes when we went for a walk round the garden). Oops - hadn't thought of that!
 
A big pool of water has collected at the lowest point of the path
(see centre left of the picture)
Several hours later, and the paths are still soggy!

Urgent action was needed! There are lots of ways to deal with poor drainage on a sloping site, including gravel-filled french drains sunk below ground, and rain gardens. After a rapid search of the internet, we decided the best option for us would be a dry creek bed leading to a sump drain. The creek bed would channel water off the paths and down to the lowest point of the garden, where it would sink into the sump drain and gradually disperse into the soil. 

We didn't take as many 'action shots' as we should have, as we were racing to beat the next downpour. But basically, the job involved clearing away soil to a depth of about 20cm from the 'creek bed' and mounding it up on either side of the cleared area. We kept the slope of the bed the same as the garden, while making sure that the level was lower than the paths that we needed to drain. We added one small flat stretch where the water can pool and feed rushes.

Once we'd dug the bed, we lined it with landscape fabric to keep the soil in place, and distributed river pebbles liberally over the surface, smaller ones in the middle and larger along the edges. A few sandstone rocks completed the picture. The whole thing only took us about two hours.

The lower portion of the creek bed. You can see the landscape
fabric peeping out in the bottom right hand corner of the shot.
It took us a few weeks to install the second half of the creek bed, which was less urgently needed for drainage purposes. The challenge with this was more aesthetic - how to make it look as if it is a real stream with a natural source. More sandstone rocks provided the answer, with the stream appearing to well up out of a pile of them, or so we hoped...  

Dry creek bed completed, with the first plantings of rushes
in place on the lower stretch
 Well, it still doesn't look that natural does it?!? Hopefully once the plants start to grow up around the rocks and pebbles it will seem less contrived. And at least we aren't getting wet feet if we take a walk after rain (unless we walk past the spot where the as-yet-unconstructed sump drain will be situated). 

Some websites we found really useful (though didn't follow 100%) were:
For an interesting read on making best use of water around the house and garden, check out the Michael Mobbs saving water special on The New Inventors.

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