Op hoeveel meter onder de rooilijn bevindt zich het grondwater in Istanboel (Turkije)?

Het was rond de 30 meter. Door drinkwaterwinning ed is het op plekken tot 150 meter onder de grond gedaald.

[quote van origineel in engels]
The decline in the water table due to unsustainable abstraction ranges from 30 metres to as much as 150 metres in some areas. Both surface and groundwater quality is monitored through 51 observation stations scattered throughout the two basins.
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