In my dry (during the dry season), windy, hot, tropical, deforested, deserted oasis, we have the double challenge of water. When it's dry, our clay soil turns to cement and sheds any water that TRIES to come. In the rainy season, since we're situated in a bit of a low spot, we get hundreds of thousands of gallons of water rushing through like a river. Okay, not usually THAT bad, but it does rush through and deposit even more clay soil, leaving slick mud. After a day or two, dig down and it's completely dry 18 inches deep.
I've decided a sort of swale (and more to come) is the solution. I've started it at our driveway (dirt drive which has turned into a canal to direct the water right to our doorstep) with a fairly narrow swoosh (is that a technical term?) Away. It roughly follows the very gradual slope in that spot, curves down and back up a bit to meet up with what will be my banana garden. The Swale will be deepest and widest at the bottom of the curve and then will direct only overflow into the bananas. I don't want it to focus the water into the bananas, but hold the bulk at the curve. Total length is maybe 70 feet from driveway to (future) bananas. Width is around a meter (not measuring it, just eyeballing it and letting the spirit of the Swale direct me). Depth is currently about a shovel deep. I'm waiting for the next big rainfall to determine if I need to go deeper or make other changes.
The end coming from the driveway is bare, and the end by the banana garden spot has decent shade trees and some weeds and grass growing. Most is full sun.
Since the water really does a number on the topography when we get down pours, I'm thinking of planting lines of vetiver in a dash pattern at the top of the Swale where the water comes in. This would help to keep the soil in place. I'd make the "dashes" 3 plants long or so, and break for the same distance. Then I'd do the same thing about a meter back, but placing the dashes where the spaces are . . . If that makes sense. The idea would be to slow the flow, hold any organic material, and let the groundwater recharge there. I might pop some moringa or Lycenna trees in there too for additional shade and roots and to contribute more organic mass.
Inside the swales, I'm not sure what to plant. There's a couple of local ground covers that I might be able to encourage in there, but most of the local things are less happy with wet feet. Maybe check out the local ditches and see what's in there? I'd like to try perennial peanut ground cover, but the seeds are kinda expensive.
I'm looking into trying some clumping bamboo inside the Swale before the mound (sorry, my lingo isn't up to date). I will plant some moringa on bottom of the far slope to hold the mound, and also might plant more vetiver there.
So I have probably two nice sunny spots on the Swale where I can plant a nice fruit tree. What do you think would work best here? It should be something I can get here in Haiti. And probably not enormous, since I have some larger trees (baby trees that will grow large) planted in the vicinity.
Right now the ground is almost bare, so thoughts on keeping things in place would be appreciated too!
Thanks for all the helpful advice I've gotten since finding this community! I'm totally relearning how to garden in a different environment!
Wow, looks like you have done a big chunk of work by hand there - nice job!
I don’t pretend to be a swale expert, but if you haven’t already looked at Mollison’s permaculture book, he covers earthworks pretty well, as does Lawton in his videos.
I think generally the goal is that they be on contour to catch and soak, although in your case where you are trying to move the water, a 1% slope is what I think is recommended. Otherwise I guess it is just a ditch! :).
Agree with your plan on ground covers - what grows in ditches is probably your best bet. I like the dots dashes concept with the vetiver grasses - let us know how that works! But, if on contour or a 1% slope, hopefully the water won’t be moving too quickly.
Will it be challenging to get growers started in the dry season? Maybe some thick mulch?
“All good things are wild, and free.” Henry David Thoreau
Rainy season is supposed to start this month, so I'm planning to put the vetiver in at that point. I'm basically going to let the rain tell me what I need to adjust in the depth and slope since I don't have anything other than rudimentary tools.
The purpose is to catch and soak. The overflow into the banana garden is a secondary water source for the bananas (the bananas will be in the little Grove of trees). I plan to plant some trees on top of the mound that will be watered by the rainwater soaking in below.
Mulch is a little bit of a problem since, as you can see, there is little organic material available to us other than the native trees that have thorns. I can use those around the base of the trees as long as I don't spread out too far. I'm interested in more info on Lawton's "spinney pits" where he puts his thorny branches. I'm not exactly sure the science of it other than having an out-of-the-way place to let them break down. It sounds like he might be using them to hold moisture deep in the ground as well?
I tried to show the spot 10 meters or so up from the current location, where I'll make my second Swale. That one will start at the driveway as well, curve down to the banana garden again, with a moderate overflow option, and then will curve back up again to catch the water on the other side of the banana garden where we have the largest amount of flow with each hard rain. I'll make some other similar swales on that side too, I think, once I can determine the effects of these swales. And combine that with the vetiver dashes. I'm actually thinking of slightly curving the dashes to serve as better catchments for the water. It's all a trial and error right now though.
I'm very impressed that you've been able to dig so much before the rainy season starts! Doesn't the clay soil bake solid? Our ground -- quite sandy in most of the areas we've been digging, but lots of clay pockets around -- gets nearly impossible to dig when it hasn't rained in months here, so digging our water movement earthworks and garden swales and berms for our latest garden area was a months-long process as we were able to knock it out without killing ourselves.
What kind of trees are your tall thorny trees, did you say? Our only woody mulch source is also thorny: our mesquite trees, also affectionately known as "murder bushes." Since it's what we have, we just use it and try to avoid the thorns as much as possible. We wear our many scratches with pride. ;)
We also base our earthworks on trial and error and repeated observation. We've found that the best (and often the only) time to dig and modify our canals and swales is when it's raining and actively flooding and filling these channels, so we expect to get wet and muddy!
For what it's worth (and this may well not be kosher permaculture, I don't know), we allow "weeds" -- grasses and Palmer's amaranth, mostly -- to colonize the banks of our water redirection canals to prevent erosion but don't actively plant anything in them. The water moves along them at quite a clip when it rains a good amount and keeps the bottoms of the ditches bare of plant material. This helps keep our driveway and footpaths from flooding and leading that floodwater directly to our front door.
We slow the water down first using grade and branching (i.e. many different options of places for the water to go) when it reaches our garden areas, then the garden swales are heavily mulched and planted mostly with nitrogen-fixing and fast-growing beans. We primarily plant tepary beans because they love our desert-with-monsoon climate, and we seed them into the walls of the swales (our swales are quite deep and narrow, between 18" and 2 ft. deep by about 1 ft. wide on average, and deeply mulched, so we don't seed the bottoms). Cowpeas/black-eyed peas also do pretty well in our swales, and we've got a common pole bean called mechudo that's a pinto-black cross that requires a longer season but does pretty well if we add mulch-buried greywater drip irrigation lines to the monsoon floodwater (this is true of our older garden area). We plant yucca stalk teepees in the berms near the mechudos so they can climb and shade other parts of the garden. We plant mixed squash near the tops of the swales as they meet the berms -- the "shoulders" -- as well as some devil's claw (Proboscidea parviflora) to hold soil, provide shade, and bear fruit.
Our swales surround "tree islands" of pre-existing (but increasingly happy) mesquite, where we've also planted other native and non-native food-bearing trees and bushes in sunken beds and will be planting more prickly pear in raised sand and gravel beds.
In the last couple of heavy rains, we observed that excess water is still flooding slowly out of the top/back of both garden swale areas, so I just started digging what I'm calling a "tuber delta" at the upper end of the feeder canal to the newest garden area after it climbs a little and becomes the last mulched and planted garden swale. It widens out into a deep delta from the extended swale, and I'm surrounding it with a berm. Once I've finished digging it out, I'll add compost, then chop and drop, then woody mesquite chip mulch, and I'll plant all the roots and tubers in there that I haven't been able to plant elsewhere because digging them up would mess with the careful grading of all the other planting areas. I don't have pictures of this yet, and the digging is slow-going even though the ground is softer now in rainy season because I can't handle that intense sun for too long, so I dig in little bursts as I can.
Apologies that some pictures below are blurry -- the low light was a challenge for the fancy camera.
"Do the best you can in the place where you are, and be kind." - Scott Nearing
There's a technique (I don't recall the name right now, if anyone can help me) (Zai pits!!) where you dig a bunch of holes, maybe 1 foot diameter x 1 foot deep, in a grid pattern (or whatever you like) and they help the water soak down when it rains. I saw a video of it being used in Africa, and he dumped any mulch he could into the holes as he could, and put worms in, and planted things in them. He had lovely soil after a few years. It gives the good stuff (fungi and worms etc) a home base to spread from, and connect up with each other. In your area you might consider them is addition to your swales. Swales to move water that's amok, Zai Pits to soak it down.
And if you can grow vetiver, I'm jealous, that's one I really want. Too cold here. I love the perfume made from the roots, I love the idea of having a deep rooted erosion control that makes the scent I like (khus is the common name for the scent.)
I'm enjoying your threads/posts, seeing what you are doing there!!
Very interesting responses and photos! And that idea of digging small pits sounds very interesting. We have 200 acres of mostly wilderness to work on, so chances are we'll have ample opportunity to try many different methods. I think Lawton's "spinney pits" are basically based on that idea of making a place for water to soak deep into the earth a few of those could make a big difference on our flooding.
Vetiver does grow quite well here when the goats don't eat it. If we can get it established in the rainy season (which just MIGHT begin tonight given the full cover of clouds we finally have), it will survive grazing, especially if we plant a lot. I can buy a big sack of plugs (grain sack) for about $5.00. Then it's just a matter of getting it into the ground. My other major hobby (or one of them) is collecting and trying perfume, and vetiver is one of my favorite notes. I also use the essential oil (easy to come by here, since Haitian vetiver is the most desirable) for face and hair.
The reason I was able to dig was that I waited until we had a good soaking rain, then dug the top down, then when we had another rain it softened it up pretty well. Also, hubs bought me one of the local hoes designed to break up this clay ground, and it glides through this stuff! The clay cracked my shovel blade! But the hoe is not phased.
And yes, our pups like to "help" with the earthworks projects too!