Tough math calculation

[Borys]

Ahoj!
Imagine I want to move 30 cubic kilometres of water per annum. 200 km from one body of water to another. 25 metres difference in height. What size river do I need?
No, I do not know how recalculate cubic kilometres into acre-feet.
Borys

[Korpen]

Hm, that gives a avarge flow of 951m3/s, so something on the scale of Vistula (or 1/2 the Donau). Considering the small difference in height, I suspect that the pace of the water will not be high.

[The Rock Doctor]

Geez, two of us got suckered into this?  I got the same number, for what it's worth.

Wikipedia provides broadly similar numbers for the Don and the Shatt-Al-Arab/Euphrates.  That implies a lot of digging.  Don't you wish you'd thought of this before sending all those Swiss contractors home?

[Borys]

Ahoj!
The Don is IIRC 20-24 cubic kilometres a year?

Borys

[The Rock Doctor]

The Don's listed at 935 m³/s in the virtual tome that is Wikipedia...so about 29.5 cubic kilometres per year.

[Borys]

Ahoj!
Maybe I'll settle for 10 cubic kilometres p/a then - the Don is a BIG river.

100x10m - how much water would that carry?

Borys

[P3D]

Digging out a second Suez Canal?

I'll tell you if I find the needed formula.

[Borys]

Ahoj!
Actually, the Kuma-Manych canal.
Remember our terraforming, making the Aral Sea accessible by maritime traffic?
I poked around and a 200 km canal could link the Don at Rostov with the Caspian Depression. Greatest height - 40 metres.
After the Caspian is raised to world-ocean level (half a century?) some digging and lots of blasting up the course of the Uzboy will lead to the Karashor depression, and then to another depression  occasionally filled by the Sary-Kamysz lake. The bottom of the Aral is some 10m above sea level, so the buck stops at Sary-Kamysh.

Borys

[P3D]

100m with and 10m depth would have a max flow rate of 1400m3/s at the given parameters.

[The Rock Doctor]

After the Caspian is raised to world-ocean level (half a century?) some digging and lots of blasting up the course of the Uzboy will lead to the Karashor depression, and then to another depression  occasionally filled by the Sary-Kamysz lake.

Happily, you should have a few nukes to use for excavation at that point.

Dredge out the Aral!

[Borys]

Ahoj!
Thanks guys!
I will start small - 60x10.
Nukes? Yes! Beat them swords into ploughs and all that!
Borys

[The Rock Doctor]

Well, keep a few swords so you can displace all those serfs in the way.

[Borys]

Ahoj!
The serfs are fully mobile, as the mutton is self-propelled.
Borys

[P3D]

You need at least 80m width, and accounting the fudge factors and uneven slope I'd say you need 100m width.

However, Volga delivers 8000m3/s into the Caspian sea. The total amount the Don would add is not significant. And as water loss in the Caspian is due to evaporation, 10% higher flow rate would require only like 10% larger surface area to evaporate.

[Borys]

The Caspian is more or less in equilibrium, ranging from 26 to 32 mbsl over the last few thousand years or so. Estimates as to when it was 50 metres ABOVE sea level vary widely from 1200 to 120000 years ago.
Anything above the inflow of the Volga would go into area increase.
Means I need a larger canal ...
Borys