Profile Resolving In-Situ Soil Moisture Sensor

PRISMS Delivers Time Series Measurements

The ability to acquire time series measurements of in-situ soil moisture in continuous profile has long been desired in numerous applications –from waste site remediation monitoring to dam and levee health surveillance, early warning of landslide potential to improved irrigation management, as well as monitoring of land-atmosphere interactions for input to climate models.

Transcend Engineering has invented a sensing technology called PRISMS, for "Profile Resolving In-Situ Soil Moisture Sensor," that provides long-term time series monitoring of spatially resolved profiles of soil water content in the unsaturated zone.


PRISMS combines advances in the processing of TDR data with innovations in the physical sensing apparatus. These advancements enable high temporal (and thus spatial) resolution of reflectance continuously along the inside surface of a borehole using a waveguide that is permanently emplaced in contact with the adjacent soils.

PRISMS is in use by pioneering researchers investigating the role of soil moisture dynamics in important terrestrial processes. Development of PRISMS has been supported through funding from the US Department of Energy's Office of Science through a Small Business Innovation Research (SBIR) grant. 


How PRISMS Works

PRISMS uses the principle of Time Domain Reflectometry (TDR) to measures soil water content. Conventional TDR probes only provide a single measurement of an average volume. Unlike conventional TDR, PRISMS provides  detailed profiles of water content  along waveguides up to two meters in length.  





Data Gallery

Profiles of dynamic soil moisture
distribution in situ
Agreement of PRISMS lab test
results with prepared moisture
content for three soil types
Agreement of PRISMS soil column results with conventional soil moisture probes
PRISMS soil column profiles (blue) compared to conventional soil moisture probes (red)
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PRISMS Deployment

Field TDR equipment acquires
raw PRISMS data
Three PRISMS sensors on a PVC
borehole casing at Rifle IFRC
GeoProbe rig used to create PRISMS
boreholes for trial deployment
Deploying PRISMS on
FLUTe(TM) flexible borehole liner
Deploying PRISMS on
FLUTe(TM) flexible borehole liner
Inflating FLUTe liner
with food grade corn oil
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Bethel, VT 05032


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