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Profile characteristics during extended gravity drainage under falling water table conditions
Author(s) -
Watson K. K.
Publication year - 1988
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/wr024i001p00178
Subject(s) - water table , drainage , flux (metallurgy) , capillary action , table (database) , capillary fringe , falling (accident) , mechanics , geology , geotechnical engineering , hydrology (agriculture) , meteorology , materials science , groundwater , physics , medicine , ecology , computer science , data mining , metallurgy , biology , environmental health
A computer‐based numerical analysis of the equation describing water movement in unsaturated porous materials is used to provide data on the shape of the water content profile and the thickness of the draining capillary fringe during extended gravity drainage when the water table is permitted to fall at a constant velocity to a considerable depth below the surface. These velocities of water table fall are considered in conjunction with zero and nonzero surface flux conditions. The numerical results are used to assess the validity of an approach based on the assumption that during extended drainage the draining profile retains its shape with continued water table movement. For the zero flux case the assumption is of limited use whereas, in the presence of an applied surface flux, the profile shape may be accurately defined depending on the magnitude of the rate of water table fall. In calculations involving the thickness of the draining capillary fringe the equations developed using the constant shape assumption reduce to the equivalent Green and Ampt forms.