Hydraulic conductivity of sandstone samples

Saturated hydraulic conductivity (k) describing the ability of the porous media to allow flow is defined by Darcy's low. Beside pore space properties it depends on the properties of liquid; therefore it is conventionally determined for water at 15 řC. Values of hydraulic conductivity vary between m/s and m/s for sands and sandstones and rises with increasing grain size and porosity. Hydraulic conductivity can be estimated by empirical formulas or measured by laboratory and field methods. Laboratory determination includes the constant head and the falling head permeameter tests. The constant head permeameter test is suitable for material with values of hydraulic conductivity ranging between m/s and m/s; the falling head test for values between m/s and m/s. Unsaturated hydraulic conductivity is a function of moisture (and pressure head). Retention curve describing the dependence of moisture on pressure head is the basic characteristic of each material. The unsaturated hydraulic conductivity can be calculated from the parameters of retention curve and the value of the saturated hydraulic conductivity using Van Genuchten - Mualem formula (1980). Fine grain rocks with small pores have higher values of hydraulic conductivity than coarse grain rocks in condition of significantly negative values of..