Soil hydraulic properties determine the rate at which water and other fluids move through soils. It also determines their water holding capacity, microbial activity, and biogeochemical processes. Soil hydraulic properties have a first-order effect on the transport of chemicals through soils, and the associated rates of biogeochemical processes that rely on the availability of various substances in pore water.

EMSL uses a specialized system for the semi-automated measurement of soil hydraulic properties (also known as relative permeability-saturation-capillary pressure, or k-s-p, relations) using the multi-step outflow method. This system and associated analyses provide data and parametric descriptions of the water retention characteristics of the soil and hydraulic conductivity as a function of water saturation. This experimental system allows measurements to be performed on intact or repacked core samples. Custom fittings and end caps can be machined, as needed, to accommodate cores of different sizes. Columns can also be fitted with current and potential electrodes for concomitant measurement of electrical resistivity to determine petrophysical relationships.

Research application

• Supporting the Terrestrial-Atmosphere Processes Integrated Research Platform, these resources provide critical data and parameters needed to model water flow and solute transport processes in variably saturated porous media.

Available instruments

Instruments used for soil hydraulic property measurements include high-precision, calibrated pressure transducers; mass flow controllers; and electronic balances. System control and data acquisition are performed using programs developed with National Instruments LabView software.

Tips for success

• Users should consult with us prior to submitting a proposal. This ensures suitable experimental resources will be available for your planned research and that your research plan will provide the data needed to address your science questions of interest.