Distance in between swales depending on slope and rain?

I am wondering how far apart swales should be from one another. I have some 1 down 4 across slopes, some a bit steeper, but just a bit, and then some that are less. We are talking 2.5km of differing slopes.
The annual rain is 600mm, Villacastin, Spain, 1200-1400m, cool mediterranean.
I once heard Bill say that on steep slopes put them 3 meters apart, and go to 150 on the plains. Is there a general rule, or idea of the distance between swales depending on rain and slope?
Thanks,
Rob

 

I'll kick off the responses with some words from Bill Mollison in Introduction to Permaculture...

I look forward to further discussion of this.

 

https://permaculturenews.org/2010/12/15/a-guide-to-back-flood-swales/

Look for Section 3 but it's not exactly what you are after.

 

Some of Darren Doherty's observations on swales, including those of Bill Mollison and Geoff Lawton. Climate specific.

https://forums.permaculturenews.org...ales-Vs-Mounds-Some-Concepts&highlight=swales

A 1 in 4 slope will be a safe working limit in most tractors

 

Geoff's comments about swales at the end of the article sure do get me excited about swales!

If I didn't have to look after the kids I'd be outside with floodlights digging swales now!

 

I've attempted a broadfork dual-line punch across a Bunyip-measured contour standing above the the line and pulling the soil up. Makes a mini-mound, with gaping holes in it. Plan is to put Vetiver across that for establishment, trees when the weather is good.

 

Interesting SOP, do you have some photos? I'd like to see it.

 

I don't have any, plus it would be hard to make out.

I can explain though: Contour measured and staked. 7-tine broad fork (Gundaroo Tiller) into a decomposed granite soil. First line on contour, inserted and the fork levered down to 45 degrees. Second line 20cm behind. Makes a lumpy, lifted area that rain woul penetrate and slow on, but only smaller amounts. Figured it would help Vetiver establishment without the pain of digging a swale, heaps faster too and the grass survives on top, as I can't germinate a cover crop for a couple of reasons.

I'll fake some photos next time if you like.

 

here are some topo and google maps of the farm

https://www.flickr.com/photos/[email protected]/

Thanks for the replies.
Rob

 

Is there any harm in putting more smaller swales closer together, versus larger ones farther apart?

 

Traditional Agriculture Question...

Hump & Hollow Drainage is basic swale methodology isn't it ?

 

Except for the word 'Drainage'. 'Infiltrator' would be a better word?

 

In Australia a swale is normally thought of as being on contour to allow sequestration of water whereas a 'drain' is used to divert water to a specific location. In the US a swale is mostly used to refer to what we call a diversion drain and consequently is not on contour.

 

Hi Rob. As the article referenced by Matto noted, Rainwater Harvesting Volume 2 by Brad Lancaster gives a very detailed analysis of how to work out exactly what you are asking and is well suited for your type of environment.

Your design will depend on what you want to use different sections for. For example, if you wish to focus on tree growth then swales with trees on the down side, or pasture, deep ripping with a Yeoman type plow on contour or a combination of both. Or you could just start by deep ripping the entire property to sequester water straight away and then take time to develop a top to bottom approach for water catchment and management over the entire property. Don't get caught up in the semantic details of whether it should be on contour or use Yeoman's Keyline design, personally I just do it on contour because I focus on edible forest tree development but your design requirements may be different and will come together as your plan matures.

Good luck.

 

Thanks...

 

I hear what you are saying but in relation to the purpose of spread and infiltrate, on contour is of the utmost importance......
I think what you are saying is that this approach is not essential on every property but for clarity if we are talking swales or or keyline (the ripping part through the keypoint at least) then the very essence of them is that they are on contour, granted not all the rips below the key point would remain exactly on contour but the process of spread and infiltrate and erosion prevention is very similar.
I agree entirely with you about the ripping top to bottom and then adding interventions as the need becomes apparent, it's really easy to rush in and make drastic changes to the landscape through earthworks because it's Permaculture and swales etc. are obligatory .....I'm laughing because I have been entirely guilty of this before!

 

As I understand it, keyline is not on contour, but slightly off contour to direct water to the ridges.

 

I just spoke on the phone to Allan Yeoman, the original Yeoman's son, and he says to the best thing is to keyline plow the entire farm. That is is a much better method than swales (what is he going to say). The thing is, I think he's right. He says to use swales as catchment for dams and for diversion from dams for irrigation of the land, but that other than that, the best way to infiltrate water into the ground is through the Yeoman Plow. I am upside down right now.

 

I'm originally from Houston, Texas and lived sometime in San Antonio Nice to see a fellow Texan