Trouble understanding how to design drainage ditches on sloping land

I read from the John Seymour book that for a sloping field you should make an open cutoff ditch and redirect it to the bottom somewhere.

Sounds very simple however my attempts so far have been anything but.

I don't get how the water from the top cutoff is supposed to reach a place where it will be able to go downhill because the ditch parts I made so far are just ending up having pools and not going left or right, just staying there stagnating. Is that bad or is that normal and they will flow sideways once there is enough liquid? I am wondering if the water, if stuck there, won't just absorb back into the soil again or if it is there does that mean it is water that would otherwise have soaked into the field?

I have a stream running through the middle of the field so thought to direct, at least the closer parts, to where the stream starts at the top.

I have already tried this but because there is no pitch really to the cut off ditch parts I made at the top they are just staying stuck there as mentioned.

Am I supposed to make the top ditches slope deeper and deeper until they hit the right angle junction to take them away? This would be difficult since it is pretty much flat already, not the field I mean the cross section where digging the cut-off, and I soon hit big rocks, due to high clay content. John Seymour's diagram does not indicate anything like that. It just shows a flat ditch at the same level, but stepped down of course, as the ground level.

I have been trying to look things up online but details are very sparse about the technicalities of making them. They generally just talk as if the reader would already know how to make them.

So advise welcome!

Where I am, the goal is usually to get the water to slow down and infiltrate to ensure our well stays productive during our drought period.

It would help to have a diagram of what you're trying to do? Some ideas of the slopes you're concerned with.

Also some idea of why this water is a problem - if the land slopes, doesn't the water just run off naturally? If you want it to infiltrate faster, that's were Key Line Plowing can theoretically help, particularly if you drop seeds into the plow lines so they start their roots down deeper.

Some info on your ecosystem and weather patterns would likewise help. What works in one climate, could be a very bad idea in another!

Jay Angler wrote:Where I am, the goal is usually to get the water to slow down and infiltrate to ensure our well stays productive during our drought period.

It would help to have a diagram of what you're trying to do? Some ideas of the slopes you're concerned with.

Also some idea of why this water is a problem - if the land slopes, doesn't the water just run off naturally? If you want it to infiltrate faster, that's were Key Line Plowing can theoretically help, particularly if you drop seeds into the plow lines so they start their roots down deeper.

Some info on your ecosystem and weather patterns would likewise help. What works in one climate, could be a very bad idea in another!

The whole field is sodden and boggy with high clay content so definitely a problem. Sounds like you are in an opposite climate to me! I am in wet UK and this field is like a bog on most of it with rushes growing all over the place.

The land slopes but it doesn't run off because of the clay, so I have been told. I read that plowing is the last thing you want to do with heavy clay soils or only in a very small window of time or otherwise would make matters worse.

Another term to research is swale.

There are generally two ideas about water. One is to get it off and away as fast as possible without erosion. The other way, which sounds like what you are looking at is to slow the water down to soak in as it goes down the hill, so you can keep more of the water for your garden/field/pasture/orchard.

If the soil is holding water too well, then I would recommend upping the organic matter and microbial life. The more organic matter you have and the more microbial life, the more places the water has to go. When it's just clay... it makes a puddle and doesn't like to soak in.

John Lester wrote: The land slopes but it doesn't run off because of the clay, so I have been told. I read that plowing is the last thing you want to do with heavy clay soils or only in a very small window of time or otherwise would make matters worse.

I am quite familiar with clay soil, and the significant difference between my climate and yours is that we get a significant summer drought. I read Patrick Whitefield's "The Earth Care Manual" cover to cover years ago and was struck by the similarities in our climates. I suggest that if you haven't read it, your local library will hopefully have a copy, and you may find it helpful, even if not directly applicable to this particular problem.

I have read that historically, UK was an incredibly boggy place and that mankind did a lot of "draining the swamp" and with the current bigger storms we've been seeing, flooding is an issue. (Aggravated by removing beavers, but my understanding is that they're being re-introduced with positive effects on managing floods.)

I absolutely agree that plowing would require absolutely perfect conditions - however, a properly designed "Key Line Plow Blade" cuts through the sod, but *does not turn it* and there is only minimal mixing of the soil. I have never tried it on our soil and the organization that was doing so seems not to have actually published their results. So I would agree - no plowing!

Our lower field tended to have standing water in the winter. Improving the depth of the grass roots by mowing higher and less frequently, and having meat chickens fertilize it, has helped enormously, but it took at least a decade. I suspect you'd like faster results.

It would be helpful to know if the field has what they call "plow pan" - a hard, impermeable layer of clay caused by repeated plowing  - is present and at what depth. If so, a trick I have used is to dig several holes - with my rock content I consider myself lucky to make it 60 cm diameter and depth, but a meter depth would be better - and fill the hole with punky wood and any green and brown organic matter you can. If it's deeper than the plow pan, it will allow the water to get under that layer. It would also support worms, which will work at expanding the healthy area. If you can make or buy Biochar (https://permies.com/f/190/biochar), adding this to the hole may help a lot.

If the issue is truly just clay soil, adding literally every bit of organic matter you can scrounge from everywhere - dead leaves, wood chips, biochar manure etc - will gradually improve it.  

The next alternative, is to consider going with Nature. Have you read about Chinampas?
Instead of thinking, "dig ditches to remove the water," the idea is to "dig narrow ponds, dumping the dirt to make higher beds, and hold the water." Traditionally they used posts rammed into the soil +/- willow woven between, to hold the dirt up high, and keep the edges of the "ditches" fairly straight sided. Some of the posts were water tolerant trees or shrubs which then provided tree hay, food, building materials etc.
https://permies.com/t/74407/permaculture/chinampas
https://permies.com/t/63991/wetlands/Images-Chinampas-share-teaching-education
If you were to attempt the Chinampas approach, having organic matter and biochar available to layer into the dirt that was being mounded up would likely help a lot to improve the soil tilth and prevent the disturbed clay from turning into concrete. The time of year you tried to start this would also be crucial. Planting into the beds promptly - even if just a cover crop - would also be helpful.

Jay Angler wrote:...

Thank you for the reply.

Chinampas seem similar to a traditional bed method in the uk called lazy beds, which I too also only recently learned about when researching these issues. Also the more well known raised beds. That is well and good for growing crops but for now I just want to do it for access purposes as I would like to get my van to drive over it sooner or later, with gravel track of course, and just walking it is rather irritating to by covered in mud just walking a few feet here and there. Of course it will never be fully free of mud but it is about taming it to manageable levels rather than total eradication.

Having a quick look this morning and I may have made a little progress.

Yesterday I dug more ditch, about 15-20 feet just above where I get in and out of my van, which had been seeing really soggy mud creeping through the gravel.

It had been raining heavily through the night and when I stepped out on the the little area of gravel. which was oozing mud and water previously, today it was firm when I stood on it. The ditch above was also well filled through the night's rains. So this may be a successful proof of concept.

I am thinking even if I have to space ditch rows as close as 10-20ft apart that will be a good result and guide them to the natural stream in the middle of the land.

It is rather a fun and satisfying process to direct water!

I'm trying to understand what the exact problem is. Is it that the land between the ditches remains waterlogged, or are you concerned about the standing water in the ditches themselves?

I'm not an expert, but my understanding is that a ditch dries up the land down slope from the ditch. Many people find this counter intuitive, but essentially the ditch is intercepting the flow that would enter the downslope section thus allowing it to dry out. If your field is as waterlogged as you describe than you may have continual subsurface flows adding water to your ditches, which is why the appear to be not emptying.

Generally you want ditches to be close to horizontal in slope - they have much of a gradient then flowing water causes erosion problems.

I guess some photos of the arrangement would be helpful, as well as a clearer idea of what you are trying to achieve.

I feel a picture or a google map might help folks understand and give a better answer.

Have you used the permaculture principle of observation?

Observation will tell where the water is coming from and help understand the best placement of ditches.

It seems the OP is on the right track now for the solution.

John Lester wrote:...Yesterday I dug more ditch, about 15-20 feet just above where I get in and out of my van, which had been seeing really soggy mud creeping through the gravel.

Nancy Reading might know where I read this, but I'm sure that archeologically, your distant ancestors used fleece to act as natural "landscape cloth" to help with this problem on their walking paths. I don't know if you have access to non-commercial fleece (I understand that many farmers simply compost their fleece as there's no market for it.)

Glad to hear that your efforts so far seem to be helping.

For a really muddy path in my field we have to walk up in our winter wet season, I dumped ~40 garbage cans a year of chipped and shredded tree bits for about 8 years before the area would stay walkable. At the time, getting wood chips from tree companies wasn't that hard - now they're much more popular and hard to get in my area. I needed something that was cheap and would eventually grow grass and I was prepared to be patient. However, it constantly amazed my how many wood-chips the soggy ground could suck up in a season! Now, with all that organic matter, it stays green despite the foot traffic, all summer.

We treat our paths the same - barrows and barrows of wood chips each year. We get stuff dropped once or twice a year for use on paths, chickens and leave to rot down for mulch for various beds. A good application of woodchips marks otherwise muddy paths walkable year round.

Michael Cox wrote:I'm trying to understand what the exact problem is. Is it that the land between the ditches remains waterlogged, or are you concerned about the standing water in the ditches themselves?

I'm not an expert, but my understanding is that a ditch dries up the land down slope from the ditch. Many people find this counter intuitive, but essentially the ditch is intercepting the flow that would enter the downslope section thus allowing it to dry out. If your field is as waterlogged as you describe than you may have continual subsurface flows adding water to your ditches, which is why the appear to be not emptying.

Generally you want ditches to be close to horizontal in slope - they have much of a gradient then flowing water causes erosion problems.

I guess some photos of the arrangement would be helpful, as well as a clearer idea of what you are trying to achieve.

I am aware that the cut-off ditch is meant to dry the land below, hence the name. What I am questioning is how to empty them when they are at a level gradient, as you say is advised, as the water is just standing there. They say you have to direct down to the bottom but I am not sure how to get it to move if it is level at the top. If they should be horizontal in slope as you have noted my question then is how do you enourage them to go downhill of on a horizontal level? The land forms some small flatish shelves in places so not perfectly sloping so in these cases how to get the water to direct to where it would be downhill again which may been many tens of feet away?

I will figure it out though I guess and getting a better idea day by day.

Another question I have had is should just one cut-off ditch at the top of the field keep the whole field below dry? Or would several be of benefit. I will just trial and error this. I can just make more below the first one until no more water builds in the new ones.

As to the standing water it is not that I am concerned about it being there I am just asking if it is normal for it to sit there and for the ditches to constantly contain some water rather than being totally, or nearly, dry once water has passed through them.

Thinking from experience when just out for walks in farmer's fields they do usually have some form of standing water in their ditches throughout the year.

I dug a good bit more but now I have a new concern! Yesterday I was digging right next to the gravel track I have laid so far and it did not occur to me at the time but I later realized that this will risk the sides collapsing when driving on the track won't it!?

In some parts I dug it is only about 4-8 inches from the track edge, which is only gravel so that would be a risk wouldn't it? How far would be safe to keep open ditches by the tracks, without risking the track falling in when under weight of a vehicle, yet still allow drainage from track area as this is the main part I want drained. I mean for longer term I want to aim to drain the whole field but for now I want drainage around the track mainly because that is what I use to drive on and so the drier I can keep it the better.

I really don't want to be in a situation where I got the van stuck with one wheel in the ditch and perhaps another in the air as I would be really in a fix then I think and have to call for assistance which is what I really want to avoid. Better to fill in that work and start again from a safer distance. Perhaps from what you mention above I don't have to do the ditches right next to the track anyway for them to benefit from drainage.

As an academic question to help understand, would the middle of a large field drain if it only had ditches around its edges even thought those ditches are far away? Is it like if you had a wide and shallow bowl of water and even if you punctured the edge, the water will still flow from the whole container? I know a little different since the soil is like a sponge I suppose isn't it? Just trying to understand the theory better.

I know I could backfill with gravel to shore them up but I don't have any spare left now and don't want to buy more. I would rather just fill these ones in and make new ones a safer distance.

The stuff I have been digging is really catching a lot of water though! I have dug almost a foot deep, similar wide, and maybe 15-20ft in length mostly and by next day or two they are half full.

John, I just cannot understand your issue, and I build roads.
Can you give us a drawing detailing the issues, and photographs  so we can clearly come to grips with your questions.