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Three‐Dimensional Analysis of Infiltration from the Disk Infiltrometer: 3. Parameter Estimation Using a Double‐Disk Tension Infiltrometer
Author(s) -
Smettem K. R. J.,
Ross P. J.,
Haverkamp R.,
Parlange J. Y.
Publication year - 1995
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 - 10.1029/95wr01722
Subject(s) - infiltrometer , sorptivity , infiltration (hvac) , hydraulic conductivity , mechanics , mathematics , geotechnical engineering , soil science , physics , environmental science , geology , soil water , thermodynamics , porosity
A double‐disk tension infiltrometer is developed to measure simultaneously one‐dimensional (1‐D) and three‐dimensional (3‐D) infiltration subject to identical initial and boundary conditions. The hypothesis that cumulative three‐dimensional infiltration is proportional to the square root of time is incorrect after a few seconds, and in consequence, estimates of sorptivity based on this hypothesis are in error. In contrast, sorptivity calculations using a recently developed 3‐D infiltration equation that includes the edge effects of the disk give accurate estimates of sorptivity. The difference between 3‐D and 1‐D cumulative infiltration is used to calculate the value of an additional infiltration parameter from the double‐disk experiment. This parameter, together with the sorptivity, provides the information required to calculate the contribution of gravitational flow during three‐dimensional infiltration. It is shown that estimation of hydraulic conductivity using a quasi‐steady‐state solution may not be justified when 3‐D infiltration is dominated by capillary flow effects. Finally, an analysis of the different timescales governing disk infiltrometer experiments under most practical circumstances is provided. A simple expression is given for the time at which the infiltration rate is within a specified amount of the final steady rate.