Two-dimensional soil water movement under the rainfall infiltration has been demonstrated using the model slope layered with traffic pan. The experimental runs of the 8° and 12° model slopes under the prolonged steady rainfalls of 80, 100, 125, and 150 mm h-1 suggest the development of the perched saturated zone above theunderlying traffic pan as well as the downslope subsurface flow ensues. Confining attention to flow in evolved saturated zone at steady state, the concept for predicting the evolution of the slope surface saturation is introduced as Return Flow Generating Point (RFGP), the location of the intersection of the perched water table (PWT) and the slope surfaceattributed to the return of infiltrated rainwater. RFGPs observed from the eight experimental runs are presented, discussed, and generalized to imply RFGP on a long uniform hillslope layered with existent traffic pan.
The Japanese Society of Irrigation, Drainage and Rural Engineering