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Getting a grip on water use
For version 0.17, we want to put in a water cycle.  So we've been getting a grip on water usage; you can see our notes here:

Most of the water used ends up in the environment, as irrigation for trees, grass, gardens, shrubs, etc.  It's a huge amount — a quarter-acre lawn (a fairly typical back yard in the U.S., I think) uses about 2800 L of water per day.  Most of us don't apply that much because it gets most of its water from the sky, but without rain, that's what it would take to keep that greenery alive.  Trees use even more: about 70 L/day per tree.

So what happens to all that water?  Seems to me there are only three fates:

  1. It evaporates — either directly, or through plant transpiration, and becomes water vapor in the atmosphere.
  2. It runs down through the soil, finds some aquifer, and ultimately pools wherever that leads.
  3. It gets incorporated into the plant itself (or some animal that drinks it before 1 or 2 happens).
This raises interesting possibilities.  We weren't planning to include a weather simulation, but with that much water going into the atmosphere, in any decent-sized colony, weather would certainly result unless you actively pull it out (via dehumidifiers).  Anybody know anything about cases of indoor rain?

And as for fate 2... I hadn't really thought about it before, but water is going to drain down to wherever the soil meets the metal, in the "lowest" (furthest from the spin axis) part of each habitat.  We will need some way to get it out again, or the soil will become saturated, and folks will start doing this on their lawns.  Not good!

[Image: stormwater.jpg]

If the soil is deep enough (and especially if there's, say, a bed of crushed lunar rock on the bottom), you could actually sink a well here and there and pump the water back out.  That's a fun thought — water wells on a space colony!

Probably more practical would be to have drainage pipes that collect the water to a few major points, like a pond or lake.  Pumps would still be needed, but not as many, and it supports the water features.

Of course if you have something like a torus or sphere with a central river, the drainage problem solves itself, as soils would drain right into the river!

Joe Strout
Lead Developer, High Frontier

After doing some research I was able to find some information on indoor rain, not very much though. It certainly makes sense that clouds would form in large inclosed spaces, but the only evidence I found of this happening was in NASA's Vehicle Assembly Building. If anyone here knows a lot about weather can they tell us what is necessary for clouds to form and whether they would form in a space colony, or if the moisture would just condense as dew.
I'm beginning to suspect that the stories that circulate about it raining inside are all urban myths. I too tried to track some down, but it all had the smell of hearsay... "It is said that" or "Supposedly" or something along those lines. A few sources make the claim more directly, but those were all fluff-news pieces, not what I would call authoritative.

So... for High Frontier, maybe if it gets too humid, it starts condensing out as dew on everything, and if it's also warm, people complain about how muggy it is. But I'm not sure you'd actually get rain.

Joe Strout
Lead Developer, High Frontier

Interesting subject. I have a friend who is a horticulturalist and he shed some light on lawn watering recently. His take is that it is better to do a single total soaking once a week rather than a daily soak. The reason being is the grass roots grow to access the water. If you do a total deep soaking the roots will stretch to follow the water as it works it's way towards the aquifer. If you do a typical light daily watering the water never penetrates deeply into the soil and the roots grow horizontally rather than vertically. A deeply rooted lawn will always be healthier and more resistant to dry conditions.

I'm just a homeowner with a brown lawn who doesn't believe in wasting water on grass but it makes sense to me.
I've often wondered if hothouses could be used to grow plants & filter water/recycle it by collecting the condensation. Not sure how it would work in the sim but if a thin guttering was run near the base where the roof meets the ground condensation could be directed as it runs down the domes into catchment areas. Not as interesting as drilling wells tho.

there is also the option to run it as a wicking (self watering) garden bed by having a layer of large particle fill (crushed moon rock, sand etc) with a geo textile layer then soil & plants/trees. they use caplillary action to draw the water up as they need it. By ccollecting & directing the condensation back into the wicking beds they become a cyclical solution for maintaining greenery & water storage.

Just some ideas, hope something is useful.
You may need condenser units to remove water from the air. I'm also thinking you'll need coolers to dispose of all the heat introduced lighting the place and running various hardware. Place the coolers in the "upper" portions of the habitat and you get natural convection. Water collected could be dropped at intervals as rain. Seems like a natural combination of functions.
Many of the answers you seek may be found here.
(09-21-2015, 09:56 PM)Pye-rate Wrote: Many of the answers you seek may be found here.

Are you sure? I just read through it, and didn't find anything at all about indoor rain. But perhaps I skimmed too quickly.

Joe Strout
Lead Developer, High Frontier

Rain no help, but they ran into the same problems of how much sunlight and space allocation of space as in a habitat. The hanger is about the same size as a section of habitat.
Fair point. It's also a great example of how "outdoorsy" it can feel inside.

I wish I could visit... does anyone here happen to be planning a Europe trip any time soon (or happen to be in Europe already)?

Joe Strout
Lead Developer, High Frontier


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