Skip to Main Content
Skip Nav Destination

Backfill impacts on moisture measurements in fractured rock

Rohit Salve and Daniella Rempe
Backfill impacts on moisture measurements in fractured rock
Vadose Zone Journal (November 2013) 12 (4)


As the scope of hillslope-hydrology investigations extend deeper, there will likely be an increase in the use of backfill to facilitate sensor installations, particularly in fractured rock. Because of the disparity in hydrologic properties of backfill and the native rock being monitored, discrepancies in measured values are imminent. In this study, we assessed the impact of different types of backfill that can be used to provide hydraulic continuity between sensors and the "measured" environment. During a period of 4 yr, the hydrologic response to seasonal wetting and drying was monitored with identical time domain reflectometry (TDR) sensors embedded in native rock, fracture infill, augured native rock, and silica powder. We found that while all backfills responded to wetting and drying events, there were differences in the response to individual rainfall events and in the amount of moisture measured. Our observations show that the use of any type of backfill for monitoring fractured rock hydrology will result in distorted measurements; however, our analysis suggests that simple calibrations between native rock and backfill measurements allow moisture content changes in the native rock to be quantified using backfill measurements. Backfill that is finer textured than native rock provides the best estimate of water content during long-term, uninterrupted drying events when the backfill measurements are calibrated to native rock conditions. Irrespective of calibration, backfill materials coarser than the native rock provide the best detection of the timing and duration of the hydrologic response to precipitation.

ISSN: 1539-1663
Serial Title: Vadose Zone Journal
Serial Volume: 12
Serial Issue: 4
Title: Backfill impacts on moisture measurements in fractured rock
Affiliation: Lawrence Berkeley National Laboratory, Berkeley, CA, United States
Published: 201311
Text Language: English
Publisher: Soil Science Society of America, Madison, WI, United States
Number of pages: 9
References: 26
Accession Number: 2014-002238
Categories: Soils
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
N39°42'25" - N39°42'31", W123°37'60" - W123°37'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Soil Science Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201403
Close Modal

or Create an Account

Close Modal
Close Modal