Water Management - Swales, Drains etc

[Susan BBPM]

We live on a hill. House at the top, stream at the bottom.

Most of the year our climate is described as 'wet'. However, we get extremely dry spells (often at this time of year when plants haven't got going and a lot of the soil is bare.

Perhaps 3 weeks ago we were wading through mud and wondering if our rose would survive being soaking wet for so long. Now our garden is baked hard clay and we have the sprinklers on all day long to try and combat it.

We have a large, paved patio at the top and in order to prevent waterlogging from that and coming through from the road we had draining installed. That catches the rainfall from the patio and takes it directly down to the stream. But I'm now thinking that in summer it'd be nice to be able to flick a switch and divert that water to the garden.

We have several large water butts - we do collect water.

But I want to start doing something with swailes or irregation. Our climate does seem to be getting hotter and dryer in summer (but not in winter!). But it's tricky as depending upon time of year you have two completely opposing goals.

Has anyone else tackled this kind of problem?

 

[Mr_Yan]

I have no direct experience with this but know of several who have and have heard a lot of horror stories of it going wrong. (My property is a square about 45 m on each side and has about 1 meter height difference between the high and low points)

Here I urge caution and seeking a professional.

I've heard of people putting in swales or terraces on grade and causing landslides with the first real rain.

 

[Susan BBPM]

I have no direct experience with this but know of several who have and have heard a lot of horror stories of it going wrong. (My property is a square about 45 m on each side and has about 1 meter height difference between the high and low points)

Here I urge caution and seeking a professional.

I've heard of people putting in swales or terraces on grade and causing landslides with the first real rain.

Our hill is very steep. Hard to say what the difference between top and bottom is, but I'd guess 5m. The bottom half is flat. I think the hill extends for 30m.

We have raised beds on the side of the hill - that's very solid. I was thinking about just small ditches - maybe 4 inches wide and deep at various points down the hill so the water collects and stands for a little while allowing it to soak deeper into the soil. But when it's wet you want the water running off as quickly as possible.

And then I thought maybe those ditches could slope towards the professionally installed drainage (which is deeply burried perferated pipe in gravel that diverts water to the stream. In winter this would speed the passage of water to the drains, but in summer we could block access to the drain causing water to sit a bit longer in the little ditches?

I take on board what you're saying. But something small like this shouldn't cause a problem (especially in heavy clay soil)? But would it work??

 

[Oliver Buckle]

I am also on heavy clay, and if it is wet I only have to dig a hole a spit deep where It has not been cultivated for it to half fill with water almost instantly, as I found emptying the litter box when the cat was sick. I have been removing the top soil making a hole down into the clay, and filling it with wood level to the surface before replacing the top soil. I am hoping the bottom half of the wood will become saturated in a subterranean pond and seep water back to the surface in dry weather.
Traditionally drainage channels were filled with brushwood, rather than gravel, and I have found pebbles, that previous owners obviously incorporated as a drainage layer, embedded in the clay they were put down on. Organic material has the advantage of remaining permeable, I am thinking all my hedge cutting will get buried that way when I get back out there.

 

[Susan BBPM]

I am also on heavy clay, and if it is wet I only have to dig a hole a spit deep where It has not been cultivated for it to half fill with water almost instantly, as I found emptying the litter box when the cat was sick. I have been removing the top soil making a hole down into the clay, and filling it with wood level to the surface before replacing the top soil. I am hoping the bottom half of the wood will become saturated in a subterranean pond and seep water back to the surface in dry weather.
Traditionally drainage channels were filled with brushwood, rather than gravel, and I have found pebbles, that previous owners obviously incorporated as a drainage layer, embedded in the clay they were put down on. Organic material has the advantage of remaining permeable, I am thinking all my hedge cutting will get buried that way when I get back out there.

I love sunflowers and we STILL have the big stalks from last year. They're like tree trunks. We had planned to shred them and compost them, but they are REALLY hard to chop up.

I wonder if digging trenches and burrying sunflower stalks would be beneficial?

I do like your idea!!

 

[Susan BBPM]

I should add, part of my problem is the raised beds on the hill. They're about 18 inches deep and filled with lovely compost.
Trouble is, the water sinks down to the bottom, reaches the clay surface of the hill and then runs down the hill. I'm having to water the beds at the same frequency of containers.

So, I'm thinking about a ditch top and bottom - one to catch rainfull and soak it into the clay layer under the beds, and one at the bottom to catch the water from the bed and stop it flowing downhill so fast.

 

[headfullofbees]

Add some of your clay soil to your raised beds; it will give you better nutrient as well as water retention.
It's the "wetting agent" in many proprietary composts.

 

[Oliver Buckle]

The clay I dig from the bottom gets added to my incinerator in smallish lumps, them pounded a bit with the ash before being fed back in. It makes for a well drained, friable soil, but Head full of bees is right, some clay is an excellent addition. Those tiny clay particles get surrounded by a ball of water held by surface tension which keep the moisture and nutrient from draining away.