Geological WI:A Ceaseless tract of Desert...

[naraht]

Every other African River is screwed up some way for human use, lets screw up the Nile.

POD: 25,000BC. An earthquake in southern Egypt topples Gebel Tingar and blocks the Nile at the approximate location of the Aswan Dam.

Possibility A (Less Likely). The Nile turns sharply east or east northeast, cuts though the eastern desert coastal range and has an outlet in the southern red sea. It river valley between Gebel Tingar and the sea has *many* rapids and is completely useless for boat travel.

Possibility B (More Likely). The Nile turns West-Northwest into a relatively low lying area and does not have an outlet to the sea. The Nile feeds into an Endorheic basin like the Great Basin in North America.

In either case, there is a ceaseless tract of desert stretching from the West edge of Africa to the Red Sea.

Effects? The Old Nile Valley itself probably still remains a natural travel corridor between the Mediterranean Sea and the truncated Nile. In Possibility B, I think the large size of the resulting lake probably leads to a habitable shoreline, but I'm not sure which way the winds would carry the moisture, (west, I *think*).

Ideas from here?

 

[mrmandias]

Was the area you've diverted to desert in 25000 BC? You may need a much more recent POD. Otherwise, you might actually end up butterflying away the creation of the Sahara.

Also, 25,000 years is a lot of silt. Query whether by historic times you wouldn't have filled in the basin and flowed over into the mediterranean or back into the OTL Nile River Valley.

 

[MNP]

I'm curious. How are other African rivers screwed up for human use?

 

[naraht]

Was the area you've diverted to desert in 25000 BC? You may need a much more recent POD. Otherwise, you might actually end up butterflying away the creation of the Sahara.

Also, 25,000 years is a lot of silt. Query whether by historic times you wouldn't have filled in the basin and flowed over into the mediterranean or back into the OTL Nile River Valley.

Because of the prevailing wind patterns and the lack of ice age, you end up with Deserts at that latitude unless the mountains and seas are such that rain gets brought into that area by monsoon. I don't think our "Lake Saladin" is going to make much difference over the entire Sahara.

The silt is a good question. I think I'd have to do quite a bit of volume calculation before determining that. I was trying to go back far enough to eliminate Egyptian civilization without screwing up the general movement of the early humans. OTOH, changing the Tenth Plague to making the Nile *never* come back is appealing.

 

[naraht]

I'm curious. How are other African rivers screwed up for human use?

The Nile is the only river in Africa which goes through farmable area while being more or less navigable for most of the year. Most of the Congo's drainage isn't that farmable and both the Niger and the Zambezi aren't as navigable from the sea inland as the Nile is without dredging. North America is sort of the other end of the scale. Half the inhabitable (to Europeans) continent is drained by two river systems (St. Lawrence & Mississippi) which have small specific areas where they aren't traversable (Niagara and Louisville (and similar breaks to Louisville on the Missouri)).

Yes there were cultures at a reasonably high level that used both the Niger and the Zambezi, but they might have benefited by the rivers being more like the Nile or the Mississippi.