A Portable Streambed Permeameter Built With 3-D Printed and Arduino Controller/Data-Logger

Abstract:

Streambed permeability is an important but difficult to measure parameter that regulates fluid exchange and riverine biological activity. We developed a portable, in-situ permeameter that works in streambeds characterized by a range of soil particle sizes. The device uses an Arduino controller to drive a pump that establishes a varying pressure head across the medium of interest. This requires a secure seal between the streambed and permeameter housing. Much of our effort was devoted to establishing this seal using unconventional means, including castable ultra-soft rubber. We determine relative permeability using both the difference in amplitude between the measured pressure gradient and that given by the hydrostatic forces of the fluid column, as well as the phase shift between the hydrostatic forcing and the responding pressure as characterized by Darcian flow through the permeable medium. We consider it notable that the data acquisition, control and fluid delivery system could equally be employed as a well-mounted permeameter for small wells, lab permeability tests in cores, as well as air permeability tests in snow and soil.