FRACTAL DESCRIPTION OF WETTING FRONT INSTABILITY IN LAYERED SOILS

Fractal theory was applied to describe fingering structure and to esti mate the effective surface tension at the wetting front during infiltr ation. A scale length of mean pore size was used to estimate the micro scopic system length of fingering. After bulk surface tension was repl aced by effective surface tension in a linear stability theory, theore tical maximum wavelengths agreed with those of experimental results wh en fingering developed in quartz sand beneath Oakley sand, but not ben eath Yolo clay.