First thing you need to get is some info on "fossil" water. The water 1000 m deep has been there for over 40000 years,. Abstracting it cannot be sustainable as it may take more then 500 years to recharge it.
You live in an very arid part and I would expect an application of more than 1500mm per year. that is 15000 m³ per ha per year. At 100000 ha that represents a lot of water. The ocean level should rise a fraction and Mr Gore might just blame that on Global warping.
Morals aside, after all you are just doing the digging. (And using the water isn't really that bad)
I think you should contact your friends in Saudi Arabia, They have some
160000 ha under irrigation using fossil water under similar conditions. and even goes down to 1200 m.
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