Considerations on settlements and urban development on a colonized exoplanet

Question

When humans are colonizing a new planet, what are the considerations that need to be made for settlement placement and development?

For this particular question, let's consider the following assumptions:

1. The colonized planet will be self sufficient; i.e. it won't just be a planet that's exploited for its resources. It won't have any contact with Earth.
2. The atmosphere of the planet is breathable but does require some initial terraforming effort to actually make it long term livable; i.e. settlers will have to live for at least the first few decades inside domes or protected environment, though can work outside those.

My attempt at the considerations are those:

1. Natural defensibility is not a primary concern for placement, or a concern at all. Humanity is united and even if war was to break out, technology would easily allow to ignore the defensive advantages of rivers and mountains.

2. Closeness to water is probably the most important factor: perhaps oceans more so than rivers. Salty water can be desalinized and ocean access enables much easier transportation of resources both from resource gathering places and to the locations of new settlements.

3. Inland settlements will be rare and probably associated with some sort of mining and, again, would favor rivers.

4. Energy production would mostly be nuclear, with plants constructed well outside the domed cities.

5. Most of the population would be inside mega-cities, which should provide transport to the work places (such as mines, farmlands etc.). Bigger factories/farmlands would possibly sprout small suburbs.

What other considerations should I make? What are the most important resources for a colonizing humanity? Besides resources, what would be the concern for placing and how would does cities grow?

Answer 1

Unless your tech level is dramatically above the present day, consideration for settlements should be the same as they were throughout the Earth's history.

Following factors may be considered prime:

1. Access to fresh water;
2. Access to food;
3. Access to transportation;
4. Availability of room to expand;
5. Natural habitability (good climate, lack of natural disasters);

Tech advances in #1 in your case may sound like a game changer - cheap and ubiquitous desalinated water would reduce dependency on rivers and aquifers. Providing that you have a redundancy in power generation and desalination, you can place your mega cities on the edge of a desert.

#2 (food) is not a big concern today as long as #3 (transportation) is good. In future, #2 is likely to become even less important, so in a nutshell, you don't have to look for places like Nile delta or Mesopotamia for your city to place.

#3 (transportation) is increasingly important. I would even say that modern city is only as good as you can get in, out or around it. You had mentioned ocean transportation, so I would say that having a seaport is a must. Look for coastal places with nice big harbors.

#4 may be critical for a city to grow. Some cities, like Hong Kong and San Francisco had started really nice, but as they used up all the land available nearby, they had become symbols of overcrowding and high housing prices. So, start in a coastal area, but not on a narrow peninsula or an island.

#5 is something that people historically didn't think too much about when founding cities (or didn't have much choice at the time). As a result, we have many cities threatened by earthquakes, typhoons, high tides, blizzards and other calamities. You have a luxury or having a fresh start, so you should be able to study seismic activity and climate, and avoid making costly mistakes.

Answer 2

You've done well to consider resource location as a primary concern. You might consider a few things as well. Every colony will need to have some stuff coming in, and will definitely have stuff going out. You need to consider what resources you need to draw on as well as how to deal with waste.

Water. I would give consideration to the locations of Aquifers a little more weight to go along with rivers. You may have the tech for desalination, but that is energy intensive and adds a layer of complication that you do not really need. Consider locating coastal towns at places that are both near a river and the ocean. If you rely solely on desalination, the failure of one of your plants would be catastrophic. The other thing about oceans is that they can and do spawn Hurricanes. Those can create problems. Coastal cities are useful if you are going to be harvesting fish for food and as a natural transportation node for large shipping.

Inland Colonies will face more of a challenge in getting rid of wastes that you would need to factor in. If your people are living in a Mega City, where does all the poop go? A mega city is going to generate a LOT of it. Granted, there are plenty of ways to cope with it. You could dump it in the river or ocean, as humanity has done from time immemorial. You could have a plant that burns it for fuel or processes it for fertilizer. There are tons of ways to cope, but you do need to address it.

Look for opportunities to build in redundancy, such as wind farms and solar to augment the nuclear power plants. Multiple water sources. Lots of crops that can be rotated for food supply. Maybe even look to genetically alter livestock to cope with the world outside the dome. Try to make it so that if any one system fails, it doesn't kill the whole colony. And do this for each colony. The series of redundancies is going to be unique to each location.

Answer 3

Older communities tended to cluster near trade routes or key resources - agricultural, mineral, industrial, services, etc. Sometimes the locations of these key resources determined where the trade route ran.

Older communities cared more about access to water for living and trade, but they lacked alternatives. We do have alternatives now, and interstellar migrants seem likely to have alternatives also.

Example: Phoenix, Arizona is in an arid valley - it imports water hundreds of miles (and food from even farther away), lacks any kind of river port, yet thrives.

Newer communities tend to gravitate toward desirable climate. Some key technologies (notably communications, transport, and air conditioning) mean that folks tend to move away from the shoveling and costs of harsh winters. Within that more desirable climate, folks do indeed tend to seek urban life.