什么是 Specific discharge; hydraulic conductivity; intrinsic permeability？

The specific discharge $\vec q$ is the volume of water crossing unit area of the medium, grains and pores together, per unit time. The hydraulic conductivity $K$ is the coefficient of Darcy’s law, in $\mathrm{m}/\mathrm{s}$ or $\mathrm{m}/\mathrm{d}$. The intrinsic permeability of the medium is $k = K\mu/(\rho g)$, in $\mathrm{m}^{2}$: it depends on the medium alone.