Irregular shaped soil samples (narrower at the bottom, and wider at the middle and upper sections) were obtained from a wetland/dam. Can any one share his/her experience on conducting lab based saturated hydraulic conductivity measurements on such soil samples?
I have not done this myself. A coworker coated the undisturbed soil sample in wax. He saturated cut the bottom and top, perhaps used some screen or one of those porous plates for support of material inside as it saturated in a container. He set up a flow system to measure water entering, and maybe leaving too, kept it running for a while until he had uniform flow. I think the small end would define your area that the flow passes through. It been 40 years, so that is about all I can remember. I am not sure if the dimensions variance you mention will effect result, as the head is greatest on the small end. The paraffin (wax) seemed appropriate for the lab test, and held the sample together.
Generally saturated hydraulic conductivity (sHC) is measured with soil sample sieved through < 2 mm air dry soil sample following the constant head permeameter as described in Richards (1954)( Diagnosis and improvement of saline and alkali soils, USDA agricultural Handbook, Vol. 60. Us Govt. printing Office, Washington, DC.). In view extreme difficulty in obtaining sHC data on irregular soil sample, constant head method data are also useful at times.
The typical constant head and falling head permeameter methods for measuring saturated hydraulic conductivity are based on Darcy's Law with assumptions of 1 dimension and steady state flow. Irregular shaped soil samples may cause flow in 2 or 3 dimensions. So, you may not be able to use the simple equations for those standard methods.
However, you could conduct the experiments, and then use a numerical model to solve the flow while estimating the hydraulic conductivity that best matches the experimental conditions (head measurements) with the irregular shape of the soil sample as the boundary conditions of the model.
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