Previously I have asked about my desert world Skara Could canals solve H G Wells Martians water shortage problems? To recap: For current purposes such a world would have gravity and atmosphere suitable for human life, but would have limited supplies of water most of which would be locked in the ice caps. Each ice cap would be surrounded by a zone with some water but which was too cold for agriculture. North and south of the equator would be a warm but very dry desert zone where it was warm enough for agriculture but without enough water.

Background information: Assume that water was originally more widely distributed, but the planets orbit was disturbed by the passage of a brown dwarf star through or near to its parent star causing a change in its orbit. Although the change in orbit had catastrophic effects, civilization was able to survive, but is faced with the problem that the limited water available is increasingly being frozen out at the poles generating the need to ship water from cold wet regions to warm dry ones on a planetary scale.

I have now decided to base this world in a pre steam technology era, but unfortunately I don’t believe that huge canals (multiple canals 200m x 10m deep running for thousands of miles) would work in this era. One possibility would be to allow magic, but I’m very wary of magic as anything could be possible and it could easily over power the scenario causing unwanted effects.

So how can I arrange for some form of magic to make thousands of miles of big canals possible, whilst preventing it from dominating and distorting the rest of feudal society that lives there? It should still take hundreds of years to build the canals. But I don’t want that much ease to change for example no magical castles easily created in the middle of the desert or easy open pit mining.

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    $\begingroup$ One problem you will have with canals, especially if you want to make them cross multiple thousands of miles and cross continents is that you'll need to pump a significant amount of water uphill--even if the norther water is already at a high lattitude. That said, canals have been built without magic but with extraordinary amounts of manual labor of similar length before. The "Grand Canal" in China, for example, is over a thousand kilometers long and was constructed in around 10 years, albeit with an estimated four million labor slaves and at similar technology level. $\endgroup$
    – Dragongeek
    Commented Oct 10, 2020 at 19:32
  • $\begingroup$ I was thinking to make the scenario easier that they might make use of existing water ways - a preformed course at the right slope that could be thousands of miles long. As the planet dried the rivers would dry up / silt up and could be re-engineered as canals. There would just need to be a suitable relatively high altitude source of ice /glaciers in an artic plateau they could tap into with a shorter linking canal. But may be I don't need magic? $\endgroup$
    – Slarty
    Commented Oct 10, 2020 at 20:24
  • $\begingroup$ If you have "hundreds of years" you don't need any magic to build the canals. Consider for example the a famous pre-industrial canal, the 240 km (150 miles) Canal du Midi, built in France over mountains and valleys in 14 years, from 1667 to 1681. Building the canals is not the main problem; having water flow in them is, unfortunately, much more difficult. $\endgroup$
    – AlexP
    Commented Oct 10, 2020 at 20:36

2 Answers 2


Mars Lives!

Thinking of Mars, perhaps there is a huge network of volcanic lava tubes interconnecting all over. these vast tunnel systems are underground reservoirs of water, which is then pumped from tunnel to tunnel. The ones that slope well are used to move water place to place as needed. You block side channels and holes.

Near the poles, actual volcanoes can be used as heat sources to melt ice and snow, and the water channeled down into a tunnel system where the water goes downward with gravity. Steam pipes are run out to where there is ice and snow and used to melt the ice to water. If you want to be really fun, volcanism can be used to lift the water, which plummets downward to where the rock is burning hot and geothermally is driven up through pipes as steam. This could provide heat and water for cities near the poles, and if you were a little more steampunk, also providing power through steam to cities above. Using condensation chambers to distill steam also solves the potential salinity issue.

Because it's underground, you aren't losing water due to evaporation. It all works like a giant plumbing system of aqueducts, but buried beneath the surface. Construction costs are reduced accordingly.

Huge lava tunnels also make a great story and worldbuilding element. Underground shipping along canals would be practical and away from the burning sun. If you decided to go a little more steampunk, you could have tethered ammonia-filled balloons transporting goods through tunnels like an underground railroad, floating over aqueducts - or actual underground trains in areas near the surface where there is enough collapse to permit air circulation.

This might also push construction increasingly underground. The sunny areas would be for agriculture, while the shaded parts of the tunnels would be cities running up the cliff faces of the tunnels. These areas would concentrate moisture to a more comfortable level in such a dry, arid environment.

A large and extensive system of lava tubes channeling water and powered by volcanos might be a bit fantastical, but it is less so than magic, and since when is fantastical a bad thing in a fantasy story?

  • $\begingroup$ I think you might have something there. I don't think that lava tubes are going to cut it for long distance transportation, but they might just be the piece I need to connect things up and not magic required - result! I feel a reality check question coming on - watch this space. $\endgroup$
    – Slarty
    Commented Oct 11, 2020 at 17:15




Mars has burrowers. These big creatures make their slow way through the substrate, just below the surface. Maybe they are wormlike, or mole-like. These creatures are large and long lived, and their burrows are substantial, with the sides compacted and hard. They are unroofed (or not) and the sides lined and fortified (or not) and then used as canals.

It is the work of generations, these canals. The burrowers can be repositioned or their trajectory changed with the intervention of humans but it takes decades or even centuries to open up kilometers of burrow.

  • $\begingroup$ an interesting concept. I would be concerned that they would be harnessed to dig all the mines, but I suppose the creatures might be a bit finickity and not be willing to go near ore deposits (bad taste?) so that might avoid the "problem" of having them dig all the mines. $\endgroup$
    – Slarty
    Commented Oct 11, 2020 at 17:14
  • $\begingroup$ The creatures are several thousand tons each. Even getting them to change direction is the work of many months. $\endgroup$
    – Willk
    Commented Oct 11, 2020 at 17:56

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