AHC Have the qattara depression be filled with water during the era of Ptolemaic Egypt

[Igor MGTOW]

Bonus Points if you make ptolemaic kingdom survive and make a map about this alternate history

 

[Lalli]

Was there even technology to do that during Ptolemaic Dynasty? And why they even would do that?

And survival until when? Century or two longer might be possible. Probably Romans still would influence to Egypt greatly but not necessarility oust the dynasty and annex Egypt. Nowadays? That would be ASB. For any dynasty it is impossible survive 2300 years. And their high inbreeding rate would make that even more difficult. As Egyptian dynasty Ptolemaic dynasty lasted quiet long anyway.

 

[Arkenfolm]

What benefit would they possibly get out of this? I believe if you divert the Nile then all you get is a mediocre agricultural region that while potentially useful today as Egypt has a huge population and great demand for food, it also reduces the flow of the main Nile. If you use the Mediterranean than you get a salt lake useless for anything but fishing.

The technology that makes the Qattara Lake useful, like power generation, mining industrial chemicals from the lake, or knowledge of how it positively alters climate, did not exist in Antiquity

Although maybe Ptolemaic Egypt survives another 2 millennia and then builds the project in the modern era.

 

[Goldensilver81]

What benefit would they possibly get out of this? I believe if you divert the Nile then all you get is a mediocre agricultural region that while potentially useful today as Egypt has a huge population and great demand for food, it also reduces the flow of the main Nile. If you use the Mediterranean than you get a salt lake useless for anything but fishing.

The technology that makes the Qattara Lake useful, like power generation, mining industrial chemicals from the lake, or knowledge of how it positively alters climate, did not exist in Antiquity

Although maybe Ptolemaic Egypt survives another 2 millennia and then builds the project in the modern era.

Un modern days you can connect the oaises with the nile to the depression by the way plants work by absorbing water and letting most of the humidity back out leading to more water and thus more plants thus which means more water repeat the cicle etc could mean more rainfall that balances diverting the nile in fact this cycle is one explanation for the prehistorical green saharah the natural increase of a little rain allowed for more plants and thus the cycle bgean .

So doing it might very well be worth it of course by 100bc no one would know the science behind this

 

[Arkenfolm]

Un modern days you can connect the oaises with the nile to the depression by the way plants work by absorbing water and letting most of the humidity back out leading to more water and thus more plants thus which means more water repeat the cicle etc could mean more rainfall that balances diverting the nile in fact this cycle is one explanation for the prehistorical green saharah the natural increase of a little rain allowed for more plants and thus the cycle bgean .

Qattara is not a particularly deep depression so the effect would be pretty limited and regional. IIRC the additional moisture from Qattara would mostly benefit Sinai and the Levant, which isn't a total loss for Egypt since they ruled a lot of that area.

So doing it might very well be worth it of course by 100bc no one would know the science behind this

I think it's one of those opportunity cost things, since there's a hell of a lot of other things Ptolemaic Egypt could do with that huge amount of manpower and money required. Qattara is about 250 kilometers away from Faiyum, and that's a huge waterway to dig--and maintain (and the waterways around Faiyum were already silting up in the Ptolemaic era).

 

[Goldensilver81]

Qattara is not a particularly deep depression so the effect would be pretty limited and regional. IIRC the additional moisture from Qattara would mostly benefit Sinai and the Levant, which isn't a total loss for Egypt since they ruled a lot of that area.

I think it's one of those opportunity cost things, since there's a hell of a lot of other things Ptolemaic Egypt could do with that huge amount of manpower and money required. Qattara is about 250 kilometers away from Faiyum, and that's a huge waterway to dig--and maintain (and the waterways around Faiyum were already silting up in the Ptolemaic era).

oh of course the quatara depresion wont cause a green sahara just explaning that is how it began water came to the coast due to moonsones plants made more moisture and depressions turned in to lakes , so this one would turn the coast and the surrounding region green over 2000 years of reduced albedo could mean that egypt in its entirety along with the levant sinai and some parts of lybia would be as well as the entire coast but not the interior as that would that would take many more thousand years or filling more depressions.
and yeat that money could be used some where else also like i mentioned no one knew about albedo or water transpiration science so yeah

 

[RogueTraderEnthusiast]

I'm not entirely sure that the Egyptians KNEW about the Qattara Depression. If we assume they did, the only real justification I can think of is to create a defensible body of water for a western border and provide a way to transport goods by ship to the Siwa and Qara oases (assuming they're still good and not impacted by the fill). It would at least mean that there is a hard-canal border to worry about in the west that can insulate the delta.

As a project, it'd probably work as a sort of punishment-labour, but I'm not convinced that this PoD would have ANY relationship to a surviving Ptolemaic Egypt. If anything it would more likely be tied to one that fell faster. There isn't a significant strategic problem in the west.

The only idea I can think of for how this could be useful in the long term is that there is a genuine reason to consider how to do primitive desalination, which might prove to be an interesting side project for some intellectual. If that WORKED then suddenly the Depression becomes an interesting geopolitical prospect.

Honestly, I don't see this best served as a Ptolemaic project. I think it'd work better as a native dynasty project. Considering the relative peace, and the threats at the time from the west, it could make sense for them to do it (again all the concerns as to how useful it'd be besides as a shipping route for the oases listed) - it could be that the canal isn't active for very long, and is undug in a butterfly-netted Ptolemaic period at a much cheaper cost.

Though there is one potential benefit that sadly doesn't justify it - it'd be an amazing source of salt - if Egypt didn't already have loads of easy salt sources already. Considering the scala of the Depression, and the saltiness present there already and only marginally diluted by the Med, you've got a potential for salt production that dwarfs the rest of Egypt. If you can find people to BUY that salt then you have a potential revenue source there, which could support the Dynasty, but.... I'm not convinced.