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Who concluded that the law of proportionality between velocity and hydraulic gradient deviates faster in very fine sand than in coarser soils?

Who concluded that the law of proportionality between velocity and hydraulic gradient deviates faster in very fine sand than in coarser soils? Correct Answer Prinz

Concepts:

Darcy’s Law states that velocity of flow through porous media is directly proportional to hydraulic gradient for any given saturated soil under steady laminar flow conditions.

 If the rate of flow is Q through cross-sectional area (A) of the soil mass, Darcy's Law can be expressed as
V = Q/A = k × I
Where,

 k = permeability of the soil   
i = dh/dl

dh = difference in total heads             
dl = length of small soil element

One main assumption in Darcy’s law is that flow of water is laminar. If flow through soil becomes turbulent then Darcy’s law is no longer valid.

Lewis and Barnes concluded that Darcy’s law is valid as long as Reynolds Number is less than 1.

Allen Hazen experimentally show that rate of flow is proportional to hydraulic gradient if the effective size of the soil does not exceed 3mm.  

Important PointsPrinz concluded that law of proportionality between velocity and hydraulic gradient deviates faster in very fine sand than in coarser soils.

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