I am unsure how to specifically define a water-rich area. I assume that it is an area of water surplus but I am led to believe it has a more specific definition for I have been asked it as a separate question.
It is given in the context of this sentence:
The government is expected to allow companies in water-rich areas to make money from selling it to drier regions
I have done a google search and nothing comes up straight away, and I haven’t been able to find a specific definition for it.
Is it exactly the same as the definition for “water surplus”?
Yes, water-rich means having a surplus of water, at least in this context. I read the article this sentence is from and thought of no other meaning.
I found one instance where water-rich is quantifiable:
Turkey, located in a semi-arid part of the world, is not rich in freshwater resources, nor does it have the greatest wealth of water resources in the region; compared to water-rich areas (i.e., those with 10,000 cubic meters of water per capita annually) such as North America and Western Europe, it has only about one fifth (1,500 cubic meters) of the water available per capita.
This quanta is from Turkish legislation, so I’m not sure if the value carries over to other countries. I hope this helps.