Quantitative value characterising a size of a drainage area A_e:
| for circular drainage area | ||
| for square-shape drainage area |
which can be is misnomer for other shapes of drainage area.
It usually makes a physical sense of an average distance from a well to the drainage area boundary.
See also
Physics / Fluid Dynamics / Percolation
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Field Study & Modelling / Drainage (fluid flow)