What is a Zone of aeration

A portion of the lithosphere in which the functional interstices of permeable rock or earth are not filled by water under hydrostatic pressure.

In your own words::

Well’s use is permanently discontinued or if it is in a condition that makes it uneconomic to repair.

Explanation:

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since there isn't any suggested answers i will give you the reason and hopefully you can figure it

south africa, or rather all of africa, has not been in the location in which it is nowadays throughout the geological past. after the super-continent pangaea started to break apart, gondwanaland, in which was africa, moved further south, and parts of it came to be very close to the south pole. because the climate in this part of the world is very cold due to the very dispersed sun rays in there, what is now south africa, started to freeze, and the conditions were right for the formation of glaciers. the glaciers existed up until the period when gondwanaland started to break apart and what is now africa started to move towards north, sp it warmed up and the glaciers melted.

they were destroyed coming out of the civil war but after he war they were booming. if you need an in-depth answer follow up with me  

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