Swales, bunds, puddles, terraces, meanders, checkdams, waffles, earthworks

For the past two decades, I have been building a wide assortment of Slow-The-Flow structures in the desert. This thread is for documenting what I've learned.

My main goal of my desert water harvesting is to slow the flow of water and sediment. When water runs off more slowly, it percolates into the ground to be used by vegetation. If enough seeps into the ground, eventually it comes out downhill as a seep or spring. The particulates carried most easily from a hill, are the most fertile. Retaining the duff, humus, and clay particles improves soil fertility. Clay retains moisture better than stone or sand, so retaining the small clay particles retains more moisture.

The most valuable source of information to me was Brad Lancaster's Rainwater Harvesting for Drylands and Beyond, Volume 2. It emphasizes building small structures starting at the highest point. It took me some time to learn that the smallest structures are the most effective and efficient.

Over the years, I learned to observe the land more aligned with how it actually is, and less in accordance with the social memes that infected my mind and prevented me from actually seeing how water flows. That's where the small, easily constructed structures come into play. They can be as simple as rotating a stick to be on contour. They are safe, and efficient.  The large earthworks that my social upbringing taught me to value are failure prone, dangerous, and hard to build. One failure upstream causes cascading failure through the whole system. However, if a small stick gets dislodged, it drifts to reinforce a spot just downstream.

The most successful water/sediment retention structures that I build are single layer check-dams. For example, by laying a row of rocks a single layer deep on the bottom of a ravine. During the first runoff event, it fills with sediment. Another layer of rocks is laid on top of the sediment, and slightly upstream. With each thunderstorm, the accumulated sediment grows. Eventually, water may seep out of the bottom of the check-dam for months after a storm. Sticks and logs are also effective for building single layer check-dams. Lay them perpendicular to the flow.  They capture sediment with each storm. Add another layer after each storm.

It might be years between runoff events. It's a joy to see the whole network of check-dams fill with sediment in one day.

Bunds only need to be a few inches tall in order to divert runoff to the roots of a tree. Bunds that size are easy to build and maintain. I used to think that building swales and water/sediment retention structures requires powerful machines. I now realize machines aren't necessary. I can build long stretches of swales or bunds by hand in a few hours, in my old age. Young kids can build even faster. Decades ago, I built a large pond, by hand, moving dirt with shovel and wheelbarrow for only 15 minutes per day. Every day.

Here is a recent earthwork. It took me a couple hours to build.

The area receives gentle snow-melt runoff only in early spring. The slope of the valley is about 24%. The slope of the new channel is around 1%. That dramatically slows the flow of water down the valley. More of it sinks into the ground to water the forest which starts just below this earthwork.

This structure doesn't fill with sediment, because the flow is gentle, and doesn't pick up sediment, and any light sediment continues to flow with the water. The fine sediment is captured by the forest.

This valley doesn't have run-off during summer thunderstorms, but just in case, the original path has rock armored spillways so that a torrential downpour could run over them rather than washing away the whole thing.

This swale was made without surveying tools, by working on it while the snow was melting. The water is the level.

This is my most recent earthwork.

Runoff occurs most often from roadways. The soil is compacted, and rain can't seep in. Therefore, it runs off. The ruts in the road turn into streams in even light rains. It's easy to divert that water into an earthwork, where it seeps into the ground over the next couple days or weeks, rather than being gone in a flash. If the diversion bund is at an angle to the road, then it doesn't act like a speed bump.

This type of runoff carries a lot of sediment with it. Ongoing maintenance of the structure includes periodic removal of accumulating sediment. The ephemeral water can attract deer, elk, and cows, which are heavy, with sharp feet which trample and damage bunds. This settling basin was dug into clay covered bedrock. Therefore, the flagstones from the hole were used to armor the top and outside of the bund. I used flagstones and cement to armor the inflow, so that it doesn't wash the road out. Eventually, I expect to armor the outflow, once I know where it levels off. The outflow is near bedrock, so armoring the outflow is mostly cosmetic.

Even after filling with sediment, about 40% of the volume consists of water trapped between the sand particles, so it acts as a sand dam.

It's harder to dig through bedrock than through loose bottom land loam, but two of us built this using hand tools in a few hours. Two people are better, cause then we can show off how strong we are to the other, and get much more work done.

The outflow is directed into a maple forest. Water attracts water, therefore, when given the choice between directing the overflow into the desert, or into an area that is already more moist, I directed it towards the moister area. I intend to plant apricot trees just below this bund.

Here are some of the more dramatic structures that I've built. They seep water for weeks or months after runoff events.

The last two photos are of a piece of wire fencing stretched across a ravine. The fencing was originally attached to a dead pinion pine. The force of the water broke the tree off, and buried it in sediment, so it ended up being an inadvertent hugel.

Thank you Joseph and thank you Beau. This was a fabulous read for me this morning. Another day this week, I was walking around my property (not desert!) that sits on top of a hill in the foothills of the White Mountains. I was thinking about a chain of small and only seasonal ponds I want to place along the flow of water I've observed. It's excellent to think I might be able to achieve some of that with only my old-lady strength and hand tools. While we receive a lot of water each year, I'm hoping to increase the amount that our land holds before the water goes on downstream. In the forested part of our property, I've observed many instances of the water coming out of the ground just below a grandmother of a tree. Rather than a single stream, our land is ribboned with water in the spring snowmelt. As temps change around here (I'm looking out at bare ground in December) the land will need to develop ways to capture more water for slow release without snow. Such good winter morning plans--thank you for the seeds of that!

Joseph Lofthouse wrote:For the past two decades, I have been building a wide assortment of Slow-The-Flow structures in the desert. This thread is for documenting what I've learned.

Thank you for documenting your experience with slowing the flow of water. I am in a far different environment where we have pretty regular precipitation but I think the principles behind your observations help produce the same outcomes, slowing down the water so it can absorb or used in place. I am in a suburban area where little consideration was given when originally designed for retaining water in place so it can soak in. Over the last couple if years I have been applying things I have learned here in Permies that help slow the water down and allow it to soak in and in some cases as in huglekultur to retain water right where it was needed. I will be reading your comments and posts in this thread and applying them on smaller scale in my 1/3 acre. Thanks

Mike Love
Central Maryland

Paul Krafel has written about his observations on how even small changes to water flow can have major consequences. He's written quite a bit - the book Seeing Nature maybe 2 decades ago, and more recently Roaming, which is online. He talks about his experience with water and soil in his TedX talk on this page: http://krafel.info/tedx-talk/

Sigurd

The central sands of Wisconsin are pretty flat. They grow potatoes here. You might have maybe 5" denivelation in a 40 acre field, so not many earthworks to be built here! Our farmers tend to go heavy on the fertilizer/ manure. I suggested they plant a "sacrificial crop" at the low end of their field to sop up the flow of nitrates before it flows into our creeks/ streams. On my property, I built a long, long pile of dead oaks/ branches. Along the ditch, about 20 ft away from it, I also built another one, somewhat lower, right alongside the ditch and imported some local topsoil to fill up: These 2 long lines of higher vegetal material work great in capturing the snow: The snow gets deposited between the 2 highlines and beyond,  and in the spring, it sinks between them, adding moisture to the trees that are growing there [a windbreak].
Across the road, they had a Norway pine  plantation that they had been growing for years to make paper. When the plantation matured, they took all the trunks out of there. They could have left the brushy stuff and piled it on the low end of the field, but no! Aaarghh! They also tore the soil to remove all the roots! They carted the whole thing in dump trucks to be sent to the various dump sites of the local towns [and taxpayers pay to maintain those dumpsites too!]
They left behind a devastated landscape with nary a stick so they could plant potatoes. The pines had dropped needles so there was about 4-5" of "topsoil" [kinda] sitting atop 35" of sand. I cried to see such devastation. Did I mention it is a windswept area? and they will not plant a cover crop either. [too expensive, he says]. When the wind blows, it looks like a sandstorm across the road and the ditches fill up with the best of this poor soil. Some of it gets blown over my 2 highlines of brush, so I benefit from their bad agricultural practices, in a way.
You might think that this post has little to do with earthworks, and indeed it doesn't. Since the goal is to slow the flow of water, however, it kinda fits.
Leaning on the chop and drop method, placing vegetal material upgradient in those swales and earthworks might be an additional way to slow the flow of water. You have to have quite a flow of water to dislodge interlocked brush. My brush is red oak that died from the wilt, so it really interlocks!
There is more than one way to skin a cat and more than one way to keep the water on your property.

Across the road, they had a Norway pine  plantation that they had been growing for years to make paper. When the plantation matured, they took all the trunks out of there. They could have left the brushy stuff and piled it on the low end of the field, but no! Aaarghh! They also tore the soil to remove all the roots! They carted the whole thing in dump trucks to be sent to the various dump sites of the local towns [and taxpayers pay to maintain those dumpsites too!]
They left behind a devastated landscape with nary a stick so they could plant potatoes.

Such a shortsighted and wasteful practice, but it's the result of bean counters looking for the quickest and greatest profit from that land, instead of planning longer term and considering the environmental impacts.
Contrasting that, I just saw an account with photos of a tree farm where they cut the pines, then they run through with a massive bulldozer with a sort of moldboard plow behind that rips out the stumps, but it plows a furrow at the same time. The stumps and brush are left to decompose alongside the new rows being made. New trees are planted in the plowed up furrows. The old stumps, roots and limbs rot down and return to the soil. The new trees are now about 6" below grade, so runoff goes naturally to water them. Far from ideal, but still a cheaper and better system!

Inspiring to hear your insistence on the possibility of accomplishing a lot of effective earthwork using handtools and muscle power! I'm starting plans for earthworks to stop the further rutting of my steep hillside road, and i don't feel i can wait until i have the funds or connections that will allow for machinery to help.