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Saturation‐matric potential relations in gravel
Author(s) -
Tokunaga Tetsu K.,
Wan Jiamin,
Olson Keith R.
Publication year - 2002
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2001wr001242
Subject(s) - saturation (graph theory) , geotechnical engineering , water content , moisture , geology , hanford site , vadose zone , soil science , degree of saturation , hydrology (agriculture) , mineralogy , soil water , radioactive waste , environmental science , materials science , mathematics , engineering , waste management , combinatorics , composite material
Some environmentally sensitive unsaturated zone sediments, such as those underlying radioactive waste tanks in Hanford (Washington State), contain large fractions of gravels and coarse sands. Coarse, granular media are also included in designs of engineered capillary barriers for subsurface waste isolation. Thus knowledge of the unsaturated hydraulic properties of gravels is needed to understand flow and transport in these critical settings. When standard methods for measuring moisture characteristics or water retention relations are used for gravels, corrections are needed in the near‐zero region of matric (pressure) potentials. The need for correction results from gravity stratification of saturation profiles within even short sample columns. Such a correction method was developed and used to determine drainage curves for Hanford gravels having characteristic grain sizes of 8.0–9.5, 4.8–5.3, and 2.0–2.4 mm. In 30 mm tall sample columns, gravity corrections were essential for the 9 and 5 mm gravels and less significant for the 2 mm gravel. Validity of the correction method was demonstrated through accurately reconstructing average column saturation‐potential relations from their predicted local saturation‐potential relations. The method and results presented here are part of an ongoing study on Hanford gravels and on limits to classical unsaturated hydraulic scaling encountered at large grain sizes.