Solution:Darcy's law for flow in a porous medium (or similarly in certain open-channel contexts) is often given by Q = KA (dh/dl), where Q is volumetric flow rate, K is the coefficient of permeability, A is the crosssectional area, and dh/dl is the hydraulic gradient.
This highlights the dependence on cross-sectional area, hydraulic gradient, and permeability. Gravitational or frictional forces are subsumed in K and do not appear separately in the simplest expression of Darcy's law.