Task: Instance Description Understanding (ontology: Earth_Environment/SWEET)

Which of the following definitions best describes the instance 'specific retention'?

A. The ratio of the Volume of water which the porous medium, after being saturated, will retain against the pull of gravity to the volume of the porous medium.
B. The ratio of the effective permeability for a given flow phase to the intrinsic permeability of the porous medium (WMO, 1974). The ratio of the effective and specific permeabilities.
C. The volume of water released from or taken into storage per unit volume of the porous medium per unit change in head.
D. A relationship between the advective and diffusive components of solute transport expressed as the ratio of the product of the average interstitial velocity, times the characteristic length, divided by the coefficient of molecular diffusion; small values indicate diffusion dominance, large values indicate advection dominance.

Answer: The ratio of the Volume of water which the porous medium, after being saturated, will retain against the pull of gravity to the volume of the porous medium.