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A world with a natural water cycle has rivers which generate a lot of transportation and ecological benefits. But gravity and sunlight drive those engines. An artificial domed community doesn’t have that unless it can somehow emulate the water vapor / rain cycle without cost. But In the case of a domed city on a planet with no water bodies, fluvial systems still would serve to disperse sediment and nutrients, as well as move wastes from the ponds and lakes to and from the surrounding soil.

I am worldbuilding a domed city on a planet with no water bodies. The city has ponds and lakes for aquaculture, biodiversity conservation, and food.

My city is on a hot dead world which is capable of generating a water vapor cycle using ambient heat outside the city, and my city does emulate a rain cycle. I don’t think it’s generating enough volume to maintain a river however, or that would be a fairly lumbering river if it were. Also, creating steam is only half of the equation. I have to condense it into rain at a large energy cost.

So I don’t think it’s feasible to rely on a rain cycle to drive the engine of rivers for cleaning and maintaining healthy water bodies, thus it seems like a completely separate fluvial system is needed anytime lakes or ponds are incorporated into an enclosed colony with no natural rain cycle.

Would it be necessary to have fluvial systems in this city?

And a corollary to this: what would such a system look like? Turbines seem bad for aquatic and lacustrine life. Waves seem bad as well due to erosion. What moves the water back uphill then?

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    $\begingroup$ Yes, you need a "fluvial system". In real life it is called a sewerage system, and it is an essential part of urban infrastructure. All cities have to have it, even if they are located in places where it basically never rains. (And you will absolutely have rain. Water evaporates from those pools and lakes, water vapor goes up, accumulates, and it comes down as rain, because what goes up must eventually come down.) $\endgroup$
    – AlexP
    Aug 30, 2023 at 15:15
  • $\begingroup$ So if I have earth-like temperatures and humidity, then obviously evaporation will occur - but it will be proportional to the surface area of the water bodies. Earth has 73% of its surface evaporating to drive the rain cycle. I'm not there. Then there's still the question of condensing the rain, which won't happen naturally. It seems that left to its own, enclosed lakes would just hit 100% humidity and become a sauna. $\endgroup$
    – Vogon Poet
    Aug 30, 2023 at 15:29
  • $\begingroup$ Just to clarify, you're talking about a domed city on a hot planet. You would need to cool the dome, otherwise heat coming through it would bake the city. I'm thinking that the water would naturally condense on the inside of the dome and run off to the dome's anchor points, where it would create small rivers. Can you explain why this isn't the answer you're looking for? $\endgroup$ Aug 30, 2023 at 16:13
  • $\begingroup$ Because I think that having the dome do as you say would be a design feature and would not happen as a matter of course, since precipitation/condensation happen on certain surfaces under certain specific conditions. Likewise, that answer doesn’t address the volume of water which is a factor if surface area and temperature, as I commented. That answer works with a specific size of city and water body, not universally. It can be a partial answer however, with the. umbers which make it work. Torrents of rain are precluded in my question as cost and resource prohibitive. $\endgroup$
    – Vogon Poet
    Aug 30, 2023 at 16:36
  • $\begingroup$ Hot dead world could have been mercury type scenario (hot minimal atmosphere))whereas you seem to be aiming more for a Venus type scenario ( hot thick atmosphere)I think it would be worth editing the question to indicate that. Biggest issue in the Venus type scenario is dissipating thermal energy. until that is solved that all other problems are a distant second. ie If thermal dissipation is solved its not that big of a deal to have in dome temperature gradients that permit rain. $\endgroup$ Aug 30, 2023 at 19:29

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Is a fluvial system necessary: no.

Where fluvial system is an open water system ie streams.

Based upon space station, antarctic stations. Various incidences of people living many months in enclosed/confined spaces.

Of course the environmental systems would need to be able to keep the environment with in a certain envelope of temperature, pressure humidity. With options for users to fine control those within there personal spaces. This would apply to practically any enclosed habitat. Where ever, however it is located. But these would not be implemented as fluvial systems.

Desirable use of Fluvial systems

Fluvial systems would be needed to provide for higher quality green spaces for mental health. Low quality green spaces wouldn't need a fluvial system such as drip irrigation or hydroponics.

If it was deemed to be desirable to have a 'natural' air/water recycling system where some fraction of habitats water/air was processed through a vegetated wetlands akin to Biosphere 2.

Implementation

For actual fluvial systems if they are large enough (kilometers) they can rely on atmosphere pressure and temperature gradients to allow for clouds and rain. ie large orbital habitats.

Anything smaller such as what the question asks would require /use simple pumps to move water around. Less complex examples are water parks, and generic water features that many building complexes have. The most complex example being: Biosphere 2, with a significant waterway traveling though multiple biomes/compartments and Rain simulation via sprinklers.

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  • $\begingroup$ I wasn’t aware how complex the new version was, can you incorporate some of the applicable aspects into the answer? Links as complete answers are discouraged. The question problem of completing the water cycle remains unanswered, save for “complex pumps.” $\endgroup$
    – Vogon Poet
    Sep 1, 2023 at 14:50
  • $\begingroup$ @vogonPoet New version of what? Biosphere2 is as far as know about the same as it was since creation with upgrades to instrumentation. $\endgroup$ Sep 1, 2023 at 22:19

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