Hydraulic conductivity

Hydraulic conductivity, mathematically represented as K, is a property of soil or rock, in the vadose zone or groundwater, that describes the ease with which water can move through pore spaces or fractures. It depends on the intrinsic permeability of the material and on the degree of saturation. Saturated hydraulic conductivity, Ks, describes water movement through saturated media.

Related Topics:
Vadose zone - Groundwater - Intrinsic permeability

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Transmissivity, T, is a measure of how much water an aquifer can transmit horizontally. It depends on the aquifer's saturated hydraulic conductivity and thickness, b:

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: T = Ks * b

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Transmissivity is important in studies of hydrogeology.

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Hydraulic conductivity is the proportionality constant in Darcy's law, which relates the amount of water which will flow through a unit cross-sectional area of aquifer under a unit gradient of hydraulic head. It is analogous to the thermal conductivity of materials in heat conduction, or 1/resistivity in electrical circuits. The hydraulic conductivity (k — the English letter "kay") is specific to the flow of a certain fluid (typically water, sometimes oil or air); intrinsic permeability (κ — the Greek letter "kappa") is a parameter of a porous media which is independent of the fluid. This means that, for example, k will go up if the water in a porous media is heated (reducing the viscosity of the water), but κ will remain constant. The two are related through the following equation

Related Topics:
Darcy's law - Aquifer - Hydraulic head - English letter - Greek letter

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: k = rac{kappa gamma}{mu}

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Where γ is the specific gravity of water (with units of force per volume, N/m³ or lbf/ft³), μ is the dynamic viscosity of water (with units of pascal seconds (Pa·s), poise, or lbf·s/ft²) and κ is the intrinsic permeability (units of m² or the oil industry unit of the darcy).

Related Topics:
Specific gravity - N - Lbf - Dynamic viscosity - Pascal second - Poise - Intrinsic permeability

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