116-5 Measuring Soil Hydraulic Properties Using a Falling-Head Borehole Permeameter.

Poster Number 131

See more from this Division: S01 Soil Physics
See more from this Session: Advances In Soil and Vadose Zone Hydrology: The Contributions of Glendon Gee: II
Monday, October 17, 2011
Henry Gonzalez Convention Center, Hall C
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W. Dan Reynolds1, Craig Drury1, Xueming Yang1, Chin Tan1, Tiequan Zhang2 and Jinyi Yang1, (1)Agriculture & Agri-Food Canada, Greenhouse & Processing Crops Research Centre, Harrow, ON, Canada
(2)Agriculture & Agri-Food Canada, Greenhouse & Processing Crops Research Centre, Harrow, ON, CANADA
An enhanced falling-head analysis is presented for measuring field-saturated hydraulic conductivity (Kfs) and sorptive number (α*) using cased boreholes finished in the unsaturated zone.  The analysis extends the original vertical discharge solution of Philip (1993) to include a “well screen” of variable length (L) and radius (a), and vertical, radial and combined vertical-radial discharge options.  Numerical optimization via Excel “Solver” is used to calculate Kfs and α* from two or more head vs. time data points.  HYDRUS-2D simulations of falling-head borehole infiltration are used to show that the Philip (1993) “flow efficiency correction”, C = π2/8, and “gravity factor”, G = r0, should be replaced with C = 1 (no flow correction) and G = 0 (negligible gravity effect).  The enhanced solution determines Kfs with ≤ 20 % error for all discharge geometries, and it determines α* with ≤ 20 % error provided that 1 ≤ L/a ≤ 4.  The new enhanced analysis improves the accuracy and utility of the falling-head cased borehole permeameter.
See more from this Division: S01 Soil Physics
See more from this Session: Advances In Soil and Vadose Zone Hydrology: The Contributions of Glendon Gee: II