164
votes
What is the utilitarian purpose of artificial waterfalls?
Low-tech climate control: the waterfalls fill the air with spray, which evaporates off and cools the populace.
The Romans used to achieve a similar effect with fountains.
- 15.5k
125
votes
What is the utilitarian purpose of artificial waterfalls?
Still water is heaven for proliferating algae, bacteria and annoying insects like mosquitoes.
A large city with large bodies of still water is a recipe for plague spreading. Having water on the move ...
- 301k
73
votes
Accepted
A way of getting the water to the top of the tall building without electricity?
In order to get water up to the top of a building, you can either carry it manually, or you can pump it. Pumps don't have to run on electricity.
Wind-powered pumps use a windmill to power the pump, ...
- 1,964
70
votes
(How) can I provide reliable water sources in a world of flying islands?
While I am answering my own question, this is by no means a definitive answer, please contribute your own if you feel there are other alternatives
There is a kind of plant in the Andean regions of ...
- 3,262
70
votes
What is the utilitarian purpose of artificial waterfalls?
Energy storage.
You use a form of energy generation with unreliable or periodic output. As a form of energy storage you pump water up into a nice big reservoir when you have surplus, then power ...
- 66.5k
65
votes
Sailing without wind, but with strong currents
You can't control your direction in a sailboat when there is just one current. Sailboats are only able to move into a different direction than the wind is blowing because they have a "second sail" ...
- 49.1k
65
votes
Pressure inside an infinite ocean?
You won't be able to have this in a universe that uses our physics.
The degree to which space itself expands or contracts is related to the cosmological constant and the density matter within that ...
- 16k
65
votes
Accepted
How long could a person survive on nothing but water, salt, and sugar?
Warning: the links go to medical Wikipedia pages and they show bodies that look quite ill. Follow with caution.
Just isotonic sugar water will likely lead to death by scurvy, beriberi, and kwashiorkor,...
- 17.2k
59
votes
What is the utilitarian purpose of artificial waterfalls?
You're looking at it backwards. Nobody added artificial waterways to a city. They did what they had to do to support building a city on top of existing waterways.
Human settlements naturally spring ...
- 8,249
54
votes
A way of getting the water to the top of the tall building without electricity?
The oldest pump in historical records is the force pump. The book that first describes it was written between 15 and 30 B.C/B.C.E.
This is the Archimedes's screw, which is one of my favorite ancient ...
- 142k
52
votes
Are 'tree waterfalls' possible?
No, at least not with classical trees. A tree can be defined as
a woody perennial plant, typically having a single stem or trunk growing to a considerable height and bearing lateral branches at ...
- 24.2k
51
votes
Accepted
Closest Proximity of Oceans to Freshwater Springs
What is the closest I can realistically have my spring to the ocean?
0 meters
When, as a kid, I went to the sea during summer, it was common knowledge that, in some places along the coast, there ...
- 301k
48
votes
Accepted
Feasible and rational way to give food and water to a prisoner?
In medieval times, this was given quite a lot of thought as castles were designed in most cases to survive a siege.
Food is an issue during a siege to be sure, but water more so; this ties into the ...
- 54.2k
47
votes
Accepted
All of the freshwater on Earth has suddenly vanished - would humanity survive?
Depending on the temperature you are exposed to, you can go 100 hours without drinking at an average temperature outdoors. If it’s cooler, you can go a little longer. If you are exposed to direct ...
- 132k
42
votes
What methods might an ancient civilization use to desalinate sea water?
Reverse osmosis.
from Aristotle, Meteorilogica.
There is more evidence to prove that saltness is due to the admixture
of some substance, besides that which we have adduced. Make a vessel
of ...
- 306k
41
votes
Accepted
Is it biologically plausible for a land animal to drink saltwater and not drink freshwater?
In animals found on Earth, the ability to drink sea water is dependent on the ability of the kidneys to export salt without damage. Sea mammals can do it -- seals, sea lions, manatees and dugongs, ...
- 47.3k
40
votes
Accepted
How to create tides in a small sea?
Rocking
Your continent is floating. Maybe it is rocking back and forth as it floats. That can happen with floating things. Any number of forces can put a body into an oscillating motion.
As ...
- 306k
39
votes
(How) can I provide reliable water sources in a world of flying islands?
Fundamentally you need a large enough body of water for evaporation to occur.
There are two options, the simplest is just to have a "water world" with an ocean down below and have the islands ...
- 77.3k
39
votes
How could an organism store a massive amount of water?
Water volume isn't a problem. The mass is the problem. Your body is somewhere around 60% water. This means even a perfect water storage mechanism can only be about 66% more efficient. You can't ...
- 133k
39
votes
Accepted
What methods might an ancient civilization use to desalinate sea water?
You can build a solar still using nothing but pottery tubes, sealed with asphalt or similar. A single unit (different design) can produce as much as five liters per day.
For continuous production, ...
- 55.9k
39
votes
Would this system work to purify water?
Do it like it's done on Earth
Using filters and machinery is useful when you need it fast or compact but on a generational ship, it's materials you can't spare.
You need garden/agricultural areas ...
- 47.9k
36
votes
Would it be possible to make a water mill without metal?
It is very possible. It's been done. The wheel itself can clearly be made out of wood, as many are even in societies that have metal. The axles and gears that transfer the rotational energy are ...
- 5,182
35
votes
How could the rain fall slower?
What you need is much, much lower terminal velocity for raindrops.
Using mathematical terms, terminal velocity—without considering
buoyancy effects — is given by$$
V_\text{t}= \sqrt{\frac{2mg}{\...
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33
votes
What would realistically happen if you could water walk?
It will be WAY harder than it sounds
Not sure if you've ever seen these floating lilly pads at any public pools, but they work more or less as described. The below body of water is completly still, ...
- 106k
32
votes
Accepted
How to make sure humans do not know the meteorological phenomenon rainbow?
You need to have direct sunlight that can be dispersed to see a rainbow. If you have only already dispersed light, no rainbow can occur.
If you have a permanently cloudy atmosphere (like it is the ...
- 446
29
votes
Logistics Problem With Water Creation Magic
Your question already contains the answer:
There's a facet of my magic system that uses a certain kind of crystal to create water out of the magic energy stored within.
The amount of magic energy ...
- 6,665
28
votes
What could cause the world to be almost completely submerged in water, naturally or man-made?
The idea of an ocean planet isn't too far-fetched. There are several moons in the Solar System - Enceladus and Europa, for instance - that have subsurface oceans. If the ice covering their surfaces ...
- 102k
28
votes
A way of getting the water to the top of the tall building without electricity?
Steam it up with a solar concentrator.
This London skyscraper can melt cars and set buildings on fire
The building — designed by internationally renowned architect Rafael
Viñoly — is a dramatic ...
- 306k
27
votes
How could an organism store a massive amount of water?
You dont have to store more water...
Just lose less water.
Camels don't store water in their humps; that's just fat. They store water in an internal bladder.
Animals lose water either through ...
- 11.3k
27
votes
What happens to my candy-creatures when they get wet and how do I stop it?
Plain sugar is soluble in water, therefore it seems straightforward that these creature would dissolve to a certain extent under water exposure.
However polymerized sugars/carbohydrates like starch or ...
- 301k
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