AUTOMATION OF A FALLING HEAD PERMEAMETER FOR RAPID DETERMINATION OF HYDRAULIC CONDUCTIVITY OF MULTIPLE SAMPLES

Abstract

Measuring hydraulic conductivity of saturated soil (Ks) is one way to quantify soil hydraulic properties. However, this technique is very time consuming for both in situ and laboratory measurements, and often one is limited to measuring only one sample at a given time. Automation of hydraulic measurements has been suggested, but this has not been done for laboratory Ks measurements. Thus, we propose to use pressure transducers to measure Ks in multiple soil cores with a falling head permeameter. To accomplish this, an automated falling head permeameter was developed by attaching pressure transducers to falling head permeameters to measure Ks of soil cores in the laboratory and a datalogger was used to record the readings. To test this method, 64 soil core samples were taken from two locations, 30 from a sandy soil, 23 from a silt loam soil, and 11 from a silty clay loam soil. The automated unit allows for six samples to be processed with minimal human oversight compared with only one sample being read manually (conventional method), requiring frequent observations during a period often >30 min. When values obtained using the automated method were compared with values obtained for the same cores using the manual technique, there was no statistical difference at the 95% level.