from The Century Dictionary.
- noun The entire basin drained by a river and all its tributaries.
Sorry, no etymologies found.
This may be on the level of the drainage-area concerned, or perhaps even on the village level.
It is known from the amount of sediment annually delivered into the sea by the Mississippi, that its enormous drainage-area must on an average be lowered. 00263 of an inch each year; and this would suffice in four and a half million years to lower the whole drainage-area to the level of the seashore.