Evaluation of Flow Pathways in a Sloping Soil Cross Section

ABSTRACT HYDROLOGIC response to precipitation was determined in situ by measuring soil moisture and water potential (continuously monitored) within a layered, sloping soil cross section. Analyses of data from natural rainfall conditions are presented to show effects of variability in the cross section on the hydrologic response and flow pathways within the cross section. The results show that soil moisture distribution returns to the pre-storm distribution within a week and that water and total potential distributions require more than four days to return to pre-storm values. Water potential contours rise fastest in the steepest part of the cross section during a storm until they are parallel to the soil surface. Following the storm, the water potential contours fall fastest in the steepest part of the cross section. Total potential distributions indicate near vertical flow pathways in the unsaturated zone and lower part of the cross section prior to the storm. Flow pathways in the middle and saturated part of the cross section are lateral toward the stream. Immediately following a storm the flow pathways in the upper part become lateral toward the stream for a time before returning to the pre-storm condition.