Modeling Interflow under the Influence of Plough Pans for a Sloping Field

Core Ideas The soil water content profile is proved and found when interflow occurs. The function of the main factors on interflow is revealed. The kinematic wave model is modified to suit the study area. Plough pans in sloping fields promote interflow. Plough pans are common in sloping fields in the black soil region of northeastern China. The mechanism of interflow differs between sloping fields in this area and other areas. Models for simulating interflow in sloping fields therefore need to be modified. We propose a mechanism of interflow under the influence of plow pans in sloping fields in the black soil region of northeastern China that extends the kinematic wave model to this area with slight modifications. Field and laboratory experiments were performed to assess the accuracy of the new model predictions. The results demonstrate that the interflow profile exists in the experimental land. The slope gradient has little effect on the interflow occurrence time, but the maximum interflow rate increases with increasing slope gradient. The higher the saturated hydraulic conductivity, the earlier the occurrence of interflow and the greater interflow volume per minute. Rainfall intensity affects the time of interflow occurrence and but does not affect the size of the maximum interflow per minute. In the stage of interflow rising, only the lower layer of the two saturated layers above the plow pan generates the interflow. At the stage of interflow withdraw, interflow is generated only in the saturated layer above the plow pan. The model simulated data, which were consistent with the experimental data, suggest that the refined model captured the temporal behavior of interflow for the study area.