FIG. 2. (a) 1-cm water retention cell with pressure transducer connected to a porous cup embedded in, and in hydraulic contact with, the porous media. The porous cup was connected to a syringe pump that provided metered water addition and removal. (b) 2-cm water retention cell with (1) water inlet connected to sintered porous plate, (2) water outlet, pressure transducer ports, and centered time domain reflectometer (TDR) probe. (c) 4-cm water retention cell showing the vertical location of the two TDR probes. (d) 7-cm cell showing the pressure transducer positions and water inlet/outlet.