Cavern Aquaculture, Capillary Action, and Dendro-Rhizo-Sculpture: Oasis Crater Garden Mandala (part 2)

My mind is still wandering the high desert before the dawn, breathing in the crisp dry air, the countless stars and the infinite depths of the spaces between them, marvelling at the austere beauty of the nearly inhospitable landscape. But at the same time my mind is furiously digging and building and planting wind-breaks and water storage, solar collecting systems that soak up the sun from dawn til dusk and store as much energy as possible in living water and living soil, making possible an ever more diverse array of life forms, even as they huddle together in the sheltering earth, holding fast against the cold dry empty entropy of space, consciousnesses burning through the long night.

A pond inside of a cave seems like it wouldn’t lose as much water to evaporation, nor lose as much heat to the night sky. What if you built some hollow spaces into the inner slopes of the crater and then used them to store water and heat?

sketchy plan of a crater with lots of caverns built into the interior slopes

Built into the south-facing interior slopes of the crater you could have a big insulated cavern/earth-sheltered-greenhouse that was almost completely glazed on the south sides soaking up the sun all day. At night you’d probably want some thermal shutters / insulative curtains. Inside of this solar-heated cavern could be multiple ponds aerated by cascading waterfalls, along with swimming, bathing, and relaxation spaces like showers, pools, hot tub, saunas, integrated with aquaculture and perhaps even tropical forest gardening. 

sketchy sketch of a cavernous solar natatorium/spa/tropical greenhouse w/ indoor ponds

Water heated in this space could be thermo-siphoned and/or pumped up to higher cisterns for storage and even perhaps periodically used to flood swales. Such flood irrigating might be done as often as monthly but would probably always be during the early pre-dawn hours, (mainly to reduce evaporation losses but perhaps also to add a little bit of extra heat at a time when it could potentially prevent an overnight frost.) Alternatively, sub-surface irrigation techniques could be used to further minimize evaporation while providing water to plants via wicking (capillary action.) Perhaps water could be piped into a series of unglazed, ceramic pots (ollas) buried in the rhizosphere.

Built into the non-south-facing interior slopes of the crater could also be caverns of varying sizes, some of which could be intentionally flooded to different degrees. Examples of some of these possible cavern aquaculture systems include: an underwater cave perhaps connected to ponds or chinampas outside, or just a chinampa or finger of a pond that is partly inside and partly outside of a cave, perhaps a duck island on a pond in a cave, or even just a trickle of clean water into a drinking bowl in the shade and shelter of a cave. Basically lots of habitable hollow spaces accessible to a variety of animals, (fish, crustaceans, reptiles, amphibians, ducks, chickens, bats, wild birds, small mammals, maybe sheep, almost certainly pigs during at least some phases for their prodigious pond-gleying, etc.) integrated with the cultivation of fungi and more shade-tolerant, water-loving plants.

some cavern aquaculture and dendro-rhizo-sculpture cavern sketches

A temporary soil-filled column connecting the submerged floor of a cavern with the tree-inhabited earth above the cavern might wick water up and eventually fill with tree roots. Once the roots reached the floor, the soil container could be removed, leaving a column of exposed living tree roots that would continue to move water up via capillary action. Maybe a variety of such dendro-rhizo-sculptures, (seriously rad and gnarly art, statues, tools, tool handles, furniture, and even structural components like frames for walls, roofs, doors, windows, and staircases,) could be grown from tree roots with enough time, patience, and foresight.

Of course, lots more structural complexity and cost is added when you start talking about building in caverns. And it adds complexity to the order of operations too, the transition from flattish land to a terraced crater with multiple caverns built in. The vast majority of the earthworks could happen almost all at once if nearly all the caverns were built and ready to be buried, but a more gradual transition might be more appropriate. Lots of questions. Still thinking about all this, but figured I would share some of my thoughts. I’d love to hear some of your thoughts and feedback, too!


Design Idea: High Mountain Desert Oasis Crater Garden Mandala (part 1)

We’re keeping our options open while considering different sites. Some of them may be more challenging than others. Short of trying to garden on the high seas or the polar tundra, a piece of high mountain desert land might be one of the most challenging sites on earth. But, if permaculture can be applied successfully in a parched and half-frozen wasteland, then the rewards would certainly be worth the challenge.

Imagine some relatively flat land up in the high desert, maybe 40 or 100 acres. It’s extremely windy, arid, (like less than 10 inches of precipitation a year,) and quite sunny, and while it can get hot during the day and in the summer, it gets cold at night and in the winter. The existing vegetation consists of mostly low scrub brush and tufts of clumping grasses. The soil is probably pretty sandy, and maybe the water table is deep and hard to access or maybe it’s shallow but brackish. There’s mountains in the distance but the surrounding land is mostly flat, barren, and empty save for a few herds of cattle and the occasional irrigated field of monocrop wheat.

This desolate landscape, or something like it, is just one of the sites we’re considering. It’s not exactly the top of the desirability list, but it is fairly cheap as far as land goes. And lately at least, I’ve been enchanted by the idea of an earthworks-intensive potential site design that rises to the challenge posed by such a hostile environment.

Below are some rough sketches and notes detailing some of the design ideas that have been bouncing around in my head.

The basic goals are to: shelter as much growing area from the wind as possible, catch rainwater and floodwater during wet times and store for use during dry times, reduce evaporation, filter out dust and salt, build organic matter, catch and store heat during hot times for use during cold times, and catch, store, and use the abundance of wind and solar energy.

These goals could be accomplished in different ways and at different scales, but the design idea I’m currently geeking out on is for maybe just a few acres. And while there are many potential variations entailing cooperation with immediate neighbors, this design idea is mostly intended for one or maybe two households.

a rough early sketch

The idea is basically to make a big crater garden by digging out a central pond, building up surrounding berms, and digging out sort of a big moat around that so the water drains towards the center. Except for a zig-zagging access road and drainage channel into the interior of the crater, most of the earthworks, terraces, swales, and paths would be concentric circles on contour. The exposed outer slopes and terraces of the crater would be planted with the hardiest, most wind-tolerant, and drought-resistant pioneer species, forming a windbreak for the interior. The sheltered inner slopes and terraces could accomodate more tender or demanding species and would be the main food production area. The central pond surrounded by the innermost low terraces and chinampas would be for the most water-loving and aquatic species. The south-facing part of the terraces on the inner slope of the crater, just above the original grade, would be ideal for passive solar earth-sheltered houses and greenhouses.

a colorful but still very rough very early sketch

There are many potential pitfalls around digging a huge pit in the desert, including but not limited to: legal/zoning issues, the angle of repose of the soils indicating just how much area will actually be required to have stable useful terraces, and the imperative to stockpile beforehand the huge piles of mulch, seeds, and plants required to immediately cover the disturbed soil upon completion of the earthworks. This idea is still in the early phases, and actual site conditions might totally change the approach, (not to mention we may choose a totally different kind of site altogether,) but for now I’m enjoying thinking about the simplicity, conceptual clarity, and efficiency of concentric circles on contour.