depletion

noun

Etymology: Borrowed from Latin depletio, depletionem, from depleō.

1. The act of depleting, or the state of being depleted; exhaustion.

   “The Great Northern 4-4-0s have all vanished, and there has been some depletion in the ranks of North British "Glens" and "Scotts."”

2. The consumption of a resource faster than it can be replenished.
3. The act of relieving congestion or plethora, by purging, blood-letting, or reduction of the system by abstinence.
4. gradual expense or use of natural resources over time.