Highly eroded landscapes, such as those within South Carolina’s Calhoun Critical Zone Observatory (CCZO), have a redistribution of soil from higher to lower landscape positions. This redistribution has altered the depth to the argillic horizon, a layer with low permeability, across hillslopes. Numerical models of hillslope and watershed hydrology often represent the argillic horizon as parallel to the soil surface along hillslopes but redistribution of erosional sediments can alter zones of interflow impacting current estimates of water flux. This study uses measurements of depth to the argillic horizon in CCZO hillslopes, along with ksat and texture measurements, in both highly eroded and relatively undisturbed hillslopes to update parameterizations of two HYDRUS 2-D hillslope models. These models incorporate spatial variations in depth to the argillic horizon, and endeavor to maintain an appropriate mass balance of eroded surface soil. We track flow paths of the ground water and use the hillslope model data to compare outflows at the lower slope between the conventional parallel depth model and the non-parallel depth model. We also compare outputs of the non-parallel depth model of a disturbed landscape to repeated soil electrical resistivity measures from a representative hillslope.
Ryland, R., D Radcliffe, A Thompson, and D Markewitz (2019): Erosional redistribution of surface soil: How has changing depth to the argillic altered hillslope interflow. Soil Science Society of America International Soils Meeting, San Diego, CA, 6-9 January 2019.
This Paper/Book acknowledges NSF CZO grant support.