Midwestern Geography

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Fun with Terraforming!

I have a desire in my game world, which is based on a far-future North America, to have a large inland sea where the Great Lakes currently are. Basically, I would like to have the majority of the lakes be internavigable with medieval tech-level ships, generating a large naval commerce area without the need for canals or overland portage.

My little map shows that Superior, Huron, Michigan and Erie are all very close in elevation (600, 581,581, and 571ft respectively) whereas Ontario is significantly lower (246ft).

What would it take to bring the first four lakes all to the same elevation, say 600ft? Would damming the Niagara River accomplish this? How about just raising Erie 10 feet?

What would be the effect on the surrounding land areas? How much of Michigan, Ontario, Ohio, Wisconsin etc... would end up under water? Is the terrain in any of those areas hilly enough to create a cool archipelago?

What would be the effect on Chicago if Lake Michigan rose 19 feet? Is the natural terrain hilly at all? A Venice-like scenario would be pretty cool.

I have a long period of undefined and unknown history, where major applications of technology or magic can explain away any necessary measures to affect the changes, but the natural landscape is likely to remain constant, and current technological artifacts, such as the Welland Canal, can be assumed to have been reclaimed by Nature.

Thoughts?

 

[Davelozzi]

Very cool idea!

Yeah, I'd say damming the Niagara should do the trick. Raising the surface of Lake Michigan 19 feet would indeed create a Venice-like situation in downtown Chicago. (Check this out: http://www.topozone.com/map.asp?lat=41.8932666847437&lon=-87.64451626201432&s=25&size=l&symshow=n) You can see the 595' elevation line snaking north-south a little bit west of I-90/94, so you know that the water would be 5' deep there. Progressing east through downtown it would get progressively deeper, of course, up to 19' at the lakefront.

Similar situations would probably occur in Detriot, Cleveland, Milwaukee, and Buffalo.

As far how the shapes of the lakes would change, you could certainly figure it out with a nice topomap but it would take a while. Looking quickly at a slight relief map in my road atlas, things would change a lot in southern Michigan and Wisconsin and across northern Illinois, Indiana, and Ohio. Northern Michigan and Wisconsin are slightly more elevated so the change wouldn't be as dramatic. The area along the southern shore of Lake Erie Cleveland to Buffalo looks pretty hilly so it wouldn't be too bad there, althought it would probably become fairly irregular with lots of little inlets between the high points.

I'm not sure exactly what the elevation changes are like in southern Ontario, but it would have to be hit pretty hard. Since the land is higher on the U.S. side, much of that water from the blocked Niagara would have to go somewhere, probably flowing north and creating another big falls somewhere else. Where exactly this occured would greatly affect the fate of Toronto.

 

[fusangite]

Wish I could help. Great idea though! I love far future reservoir campaigns (I've written two, myself -- the best being situated on the shores of Williston Reservoir in British Columbia). I also have a great interest in the Great Lakes as a setting. If you need any assistance with local aboriginal or Mormon theological information about the Great Lakes, I would be excited to contribute to your project.

 

[Kid Charlemagne]

Raising Lake Michigan would utterly swamp Chicago as it is currently built - the city was built in a swampland initially, so its very close to water level. Most of the Illinois Indiana area is very flat so raising the sea level even 20 feet or so would have a pretty big impact.

 

[DanMcS]

The lakes are pretty much internavigable now. They have rivers connecting them. Raising them all to the level of Lake Superior would pretty much do away with Michigan (there'd be some islands I guess), northern new york, pennsylvania, ohio, indiana, and illinois, and parts of Wisconsin and canada in the area. There'd also be big areas of swamp on the shores in those places, stretching another 10+ miles from the water.

If you're that worried about verisimilitude, it can't be done easily, you'd have to get a good geographical map of the area and figure out how far inland the new sea borders would be. If you're not, just expand the lakes a little on your map and say that people can ply the rivers and swamps between them on barges and other shallow-drafted ships.

 

[BOZ]

i'm curious to see what you do with this.

 

[LazarusLong42]

I like the idea, but there are several difficulties with it:

First, just damming the Niagara river won't do what you're wanting to do. You'd have to effectively create a dam some nineteen feet high that stretched across the entire river basin--a hunred miles perhaps--otherwise, in the stretch of time you're talking about, the water will just find a different way to flow downhill. (Probably by reclaiming the Welland Canal, as you noted, and simply turning it into another set of falls).

Second, the upper lakes are already internavigable, as someone said. The four (or five, if you count the bulge in the Detroit River that some people call Lake St. Clair) upper lakes have no locks between them except at Sault Ste. Marie. Natural reclamation at the Soo Locks and erosion at St. Mary's Falls would actually drop the level of Lake Superior over thousands of years.

Third--and perhaps this isn't so much a problem as an alternate solution--many of the areas you're talking about flooding are effectively swampland anyway. Toledo, for instance, was built over the Black Swamp. General estimates are that, if humans suddenly stopped maintaining the drainage systems that keep Toledo above the water table, Toledo would be a swamp again in about 50 years... perhaps less. Likewise much of Northern Ohio, Southeast Michigan, the entire area on the low side of Sault Ste. Marie, and much of the Western shore of Lake Michigan.


Now, all that mostly negative said, a different idea. Global warming runs rampant, ocean levels rise. This will also cause an increase in the mositure level of the atmosphere, and cause an increase in precipitation over much of the world. More rain falling into the Great Lakes over a long period of time will take them and their drainage basins up and over what we now consider flood stages. I doubt you could justify more than about five to ten feet of increased water level in the Great Lakes region, but that's enough to create quite a bit of havoc.

 

[Barcode]

Wow.

Thanks to the cool topomap site that Davelozzi hooked me up with, I checked out areas around Buffalo, Cleveland, Detroit, and Sault Ste. Marie. It doesn't look like you lose more than 3-5 miles of coastline in any of those places. Too bad they don't have Canadian maps, and I wish the elevations were easier to read.

So, in general, it looks like the lakes all get about 10-20 miles wider, and the rivers become straits. I'll probably design a (slightly inland) Chicago as a Venice-like city using the rough elevations from the topo-maps, augmented with some judicious use of Move Earth. That's their next destination after the current part of the campaign assaulting an insane asylum for Planetouched Half-Elven sorcerers on Alcatraz wraps up.

If I make the Big Change early on (I have about 10,000 years of intervening history to play with), I think there should be enough shore erosion that the coastal marshes will just be around the rivers, as is generally natural. I'm thinking a massive Wall of Stone near Grand Island will do the trick. Perhaps an ancient sorcerer's method of eliminating the Lake Erie coastal cities, or a specific enemy in Canada? Diverting the Niagara River through their stronghold is a pretty cool way of dispatching a nemesis.

Anyone from Ontario have the lowdown on the coastal elevations thereabouts?

 

[Barcode]

I like the idea, but there are several difficulties with it:

First, just damming the Niagara river won't do what you're wanting to do. You'd have to effectively create a dam some nineteen feet high that stretched across the entire river basin--a hunred miles perhaps--otherwise, in the stretch of time you're talking about, the water will just find a different way to flow downhill. (Probably by reclaiming the Welland Canal, as you noted, and simply turning it into another set of falls).

Bummer. So you are saying that the elevation of the river basin stays below 600 ft for 100 miles across? Not that a 100 mile dam is impossible in a fantasy world. Could be quite stunning, actually.

 

[WayneLigon]

Another source to look at is National Geographic.

North America in the Age of the Dinosaurs