tools/instructionals for putting swales on hillsides?

Hi there,
My question here relates to the development and creation of swales within a rural community setting in Malawi.
I have been working with smallholder farmers at developing better water management strategies to combat erosion and flooding and have been using swales as a design solution. The challenge appears in translating the information on width and depth - I usually go by observation and the slope but I recognize in teaching others so that they may implement further or continue teaching that isn’t feasible. Is there a formula available, or does anyone have advice on how an infograohic could be developed for steep and gradual slopes and it be informative and a teaching tool to those who may not be able to read? I’d be grateful for any advice. Thank you.

Welcome to permies, Afshan! I made your post its own thread so it'll hopefully be seen more easily and get more answers. I also added it to the Earthworks, Teaching, and Rural forums.

I hope that helps!

Thank you Nicole!

Hi Afshan,

Here is a tool that may be of use to you. Good luck!

https://www.permaculturereflections.com/swale-calculator/

I am not sure if this will help the original poster, but I obtained LIDARR Mapping for all of my farm, so my contour maps are in 2 foot contour lines not 20 foot contour lines.

When working on a particular field or earthworks project, I have found using cardboard is ideal because it is cheap and scales nicely with those two foot contours. Printing out my 2 foot contour map I start cutting out the cardboard, laying it upon layer upon layer. When I am done, I then fill in the "steps" of the cardboard with drywall compound, then paint the resulting 3 d model. In an instant, I can see where the water is moving and how I can then control it with earthworks.

I then add in my roads, swales, rock check dams, etc...whatever the project is, and now I have a really great model to show the Soil Engineer. This really helps because she can envision what I want to do with no loss of communication because she cannot picture it.

please keep us posted

If the swales are too large, labour has been wasted, but they will work.

If the swales are too small, they will overflow in major rain events. They could be expanded, but the perceived failure might lead to abandonment...


A simple process seems key. That calculator is neat, but I worry it's not accessible to the described target audience. It's also a bit odd to me that the user sets the desired swale count..

Travis, as much as I love your models, I have a sneaking suspicion that not only is there no Soil Engineer coming, there may well not be a printer... or cardboard! I know very little about Malawi, but a quick search turned up the phrase 'one of the most impoverished and least developed nations on earth'.


It seems like you should be able, for a given region with somewhat similar soils, to create a rule for thumb for swale cross sectional area based solely on slope and area, no?

It would not necessarily be very close to ideal, but if the max expected rainfall and the runoff percentage were fixed to worst case scenario values for the general area this would be a step towards a very simple guideline...

Anyone able to help take this further, if I'm not nuts?

You are right Dillion, and one "mistake" I often make is being too broad.

I know on forums that 99% of the people are lurkers, and seldom participate, but rather just read through the topic at hand and learn. I tend to make my posts more broad so that everyone learns, more so then just to answer the original posters problem. In this case it is how to make a swale lay out tool in a foreign countryy, and my reply was for a much broader audience. A "this is how I do it", sort of thing.

In some ways it is not bad. If the orginal poster cannot do so, they will just think, 'I don't have that', and disqualify my reply, but a dozen other people might think, 'Wow, that is a good idea; I can do that."

I am not sure if what I do is a "mistake" or not, but this i the second time this week I have been called out for doing so. That may be a sign that I need to rethink how I post, and limit my reply to only the problem at hand. Thanks for keeping me in check, I needed that.

Travis, I hope my comment did not seem overly negative. I absolutely see the value of the information you provided being available for other readers of the thread, and don't think it's done the conversation any harm.

I do hope to see the thread to push forward with a potentially more suitable solution for this particular poster, though!

Travis Johnson wrote:That may be a sign that I need to rethink how I post, and limit my reply to only the problem at hand. Thanks for keeping me in check, I needed that.

That's not how I see it, at all. I found your previous post incredibly helpful, and inspiring. I would be disappointed, if you stopped sharing, and who knows what information you have stored between your ears, what skills you've honed, that might be of incredible benefit to those of us who really do only read and learn, if we don't feel we have anything to contribute. When I have knowledge, I share. When I'm seeking knowledge, I try to stay quiet, because it's hard to be open to learning, if I'm not focusing on exactly that. So, you be you, lol. I, for one, truly appreciate it.

Afshan Omar:
Zai pits might be easier to explain to non-literate people, they are small pits rather  than a swale that takes math. If you are getting mare water runoff than you want, you dig more pits. No numbers that tell you how many. Look into them, might make more sense than swales in your project.
Zai

Swales are great, but zai pits are easier to explain :D

Carla Burke wrote:That's not how I see it, at all. I found your previous post incredibly helpful, and inspiring. I would be disappointed, if you stopped sharing, and who knows what information you have stored between your ears, what skills you've honed, that might be of incredible benefit to those of us who really do only read and learn, if we don't feel we have anything to contribute. When I have knowledge, I share. When I'm seeking knowledge, I try to stay quiet, because it's hard to be open to learning, if I'm not focusing on exactly that. So, you be you, lol. I, for one, truly appreciate it.

I did get out and get some pictures of a model I made for one of my fields.

The first pictures shows the satellite photo from Google Maps.

The second picture shows the model I made of the area. Sadly, because of the camera angle it is hard to see the amount of depth and terrain this field has. From left to right this field has a 100 foot dip in elevation. You can however see my plans for swales, erosion control, culverts, heavy haul roads, and our proposed off-grid cabin as indicated by the green monopoly house on the left.

The third photo just lets you see the satelite and model in a side by side comparison.