# water delivery in a desert



## ascanius (Oct 11, 2013)

Hey everyone.  
Ok so i have a small city in a desert set on a plateau ridge.  To the east are foothills and canyons running up almost to the point of the ridge.  The city is built on three hills, two hills are on an isthmus (not sure if that is the right word) that juts out from the plataeu.  The other hill is on the main portion of the plataeu.  This city was once a coastal city but the sea has receeded.  

For the city itself i imagined a sort of hanging gardens of babel, which means I need a great water delivery system.  This makes two problems.  How to get the water, and how to get the water to the tops of the hills.  I was thinking os a system of aquaducts originating from water in a cave.

The other idea i had was to use the properties of water such as turgor pressure, adhesion.  Basically the principle is the same as placing the endother of athe sheet of paper in water, the water will travel up the sheet of paper.  The same principle is how trees get water to the leaves.  From what i have read the substance needs to be porous or have very small tubes.  I was thinking of using this system for the ground water and having it travel up porous travertine to a system of cisterns that wick off the moisture.  Any thoughts?


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## CupofJoe (Oct 11, 2013)

Geology could let you have pressure fed aquifers if there was a higher watershed nearby. Water gets soaked up on higher ground somewhere else and then channelled through the rock to a lower open end. It is the same basic principle of a siphon, as long as the exit is lower than the reservoir [and there are no holes in the pipe] then it doesn't matter how low the rest of the pipe goes...
I think I saw on TV that this is apparently how there are springs in the middle of an Australian desert; the water comes from hills hundreds of miles away [and hundreds of years before]. It seeps through the rock until it breaks through to the surface again.


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## GeekDavid (Oct 11, 2013)

The ancient Romans were able to force water up hills in their aqueducts by using the pressure of the water moving downhill earlier in the aqueduct.

Whether it's a natural underground system or a man-made one that echoes the Romans, it's certainly possible to get water to flow uphill without electric pumps.


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## Lawfire (Oct 11, 2013)

GeekDavid said:


> The ancient Romans were able to force water up hills in their aqueducts by using the pressure of the water moving downhill earlier in the aqueduct.


That is interesting. I've never seen any information on that. I was under the impression that all the aqueducts were open on the top (or had wooden roofs), and they went through, not over hills. I would be very interested to see how that worked. Do you have any links?


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## GeekDavid (Oct 11, 2013)

Lawfire said:


> That is interesting. I've never seen any information on that. I was under the impression that all the aqueducts were open on the top (or had wooden roofs), and they went through, not over hills. I would be very interested to see how that worked. Do you have any links?



Roman aqueduct - Wikipedia, the free encyclopedia

Roman Aqueducts

From the above link:



> While their visible remains leave a definite impression, the great bulk of the Roman waterway system ran below ground. Channels bored through rock, or dug below the surface carried water where it was convenient and possible. Of the approximately 260 miles in the aqueduct system, only 30 miles consisted of the visible, mammoth arched structures.



What Are the Roman Aqueducts? | eHow

Or you can just type "Roman Aqueduct" into your search engine of choice, which is what I did.


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## Sanctified (Oct 11, 2013)

Sometimes we don't have to explain these things, and as an example I'm thinking of Qarth in Game of Thrones. What kind of big trade city has closed gates, no trade network and no adjacent cities? That didn't stop old Georgie.


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## GeekDavid (Oct 11, 2013)

Sanctified said:


> Sometimes we don't have to explain these things, and as an example I'm thinking of Qarth in Game of Thrones. What kind of big trade city has closed gates, no trade network and no adjacent cities? That didn't stop old Georgie.



I think the author needs to have the works in mind, but it's not always necessary to do an info dump to explain it to the reader.


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## Lawfire (Oct 12, 2013)

GeekDavid said:


> Or you can just type "Roman Aqueduct" into your search engine of choice, which is what I did.


 Oh yes, thank you. I never used a search engine before...what I was wondering was if you had any links to what you were stating was happening. Nothing you linked to backs up what you are trying to claim. 



> If water was brought in from some distance, the territory over which the aqueduct would run must be carefully surveyed to ensure that the water would flow at an acceptable gradient for the entire distance



Perhaps you meant through their cistern and pipe systems. With a completely sealed pipe, water can be raised to a level equal to the highest level that the water occupies within the system. The aqueducts were not sealed pipes, they were open, and the water continuously ran down hill (that's what water does). In the cistern and pipe system, water was stored at a high elevation, and would run - through the pipes - to areas with a lower elevation. The lower the point is, the higher the water pressure. 

Water does not flow up hill in an open channel. If it was flowing, downhill, with enough force (not how the aqueducts worked), it could flow up a SMALL increase in elevation, but it would be inefficient. Like a water slide with "hills" in it. With a completely closed system (pipes) water can flow to a level equal with it's highest level. That's it. That's physics.


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## GeekDavid (Oct 12, 2013)

HowStuffWorks "Ancient Aqueducts"



> To achieve a consistent, shallow slope to move the water in a continuous flow, the Romans lay underground pipes and constructed siphons throughout the landscape. Workers dug winding channels underground and created networks of water pipes to carry water from the source lake or basin into Rome. The pipes were typically built in concrete, but were sometimes made of lead when the government provided enough cash (lead was very expensive in 300 B.C.). *When the pipes had to span a valley, they built a siphon underground: a vast dip in the land that caused the water to drop so quickly it had enough momentum to make it uphill.* Siphons are part of the mechanism that makes toilets flush, too (see How Toilets Work).



How did the Romans get water up hills using aquaducts



> The only exception to the rule of a generally constant downhill slope to the water channel is that for certain specific tunnel segments, the Romans could build the tunnel as an inverted siphon (mentioned above) to cross a depression or valley and raise the water level on the downhill side almost to the level of the uphill side.



All you have to do is have a water source higher than the city... say, a spring on a mountain, and you an get it to run a little ways uphill.


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## Addison (Oct 12, 2013)

My brother and I did something like this one summer. We wanted to make our own little garden but our chosen spot was too far for the hoses and sprinklers to reach. But the backyard met the woods and a creek. So this is what he did, and maybe you can use it and alter it. 

We went into the woods to the creek and found the place we wanted the garden and dug. And we dug and dug and dug until our arms nearly fell off and our hands were solid calluses. The hole was as big as a King bed and deeper than we were tall. (At that age i'd put the depth at ten feet.) Then we got rocks and lined the hole.

Next we mapped out a route from the creek to our spot and dug a trench from the hole to the creek, lining it with rocks, scrap metal and wood. We made the trench deep, I forget the exact depth. When we hit the creek the trench was deep enough and angled so the water flowed to the hole. 

Next we covered it. The trench we covered with scrap wood then piled on the soil and dirt. We did this all the way to the hole, at that place we did one layer of wood, then soil, wood again and soil. We knew it would be a while before it worked, at that age we didn't know if it would work. At that age we only paid attention in history until we fell asleep of boredom. But later the soil turned to grass and plants. Even in the heat of summer it was still lush and flourishing. Thanks to the constant water feed from our makeshift duct. 

Maybe, if your city has submerged caves, your people can do the same thing. Or use the aqueduct but make it feed from the soil and roots.


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## ascanius (Oct 14, 2013)

The other idea i had was to use the properties of water such as turgor pressure, adhesion.  Basically the principle is the same as placing the endother of athe sheet of paper in water, the water will travel up the sheet of paper.  The same principle is how trees get water to the leaves.  From what i have read the substance needs to be porous or have very small tubes.  I was thinking of using this system for the ground water and having it travel up porous travertine to a system of cisterns that wick off the moisture.

anyone have any thoughts on this idea.  It is the one I was hoping to use.




Addison said:


> My brother and I did something like this one summer. We wanted to make our own little garden but our chosen spot was too far for the hoses and sprinklers to reach. But the backyard met the woods and a creek. So this is what he did, and maybe you can use it and alter it.
> 
> We went into the woods to the creek and found the place we wanted the garden and dug. And we dug and dug and dug until our arms nearly fell off and our hands were solid calluses. The hole was as big as a King bed and deeper than we were tall. (At that age i'd put the depth at ten feet.) Then we got rocks and lined the hole.
> 
> ...




I like this idea. thanks


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