Abstract

Numerical models of hillslope hydrology often use characteristics from soil classification maps to parameterize subsurface hydrologic flow paths. These soil maps, however, may lack sufficient spatial detail and may not accurately represent landscapes that have been eroded from historical farming. Therefore, a spatially explicit model of eroded landscapes, particularly in the Piedmont region of GA, could be valuable. Hillslope hydrology of the Piedmont typically involves an argillic horizon with low permeability causing high lateral flow in periods of high precipitation. In hillslope models this layer of low permeability is generally parallel to the soil surface creating different zones of interflow along the hillslope. Highly eroded landscapes, such as those within South Carolina’s Calhoun Critical Zone Observatory, have a redistribution of soil from higher to lower landscape positions altering the depth to the low permeable layer and possibly altering patterns of interflow. This study used extensive soil sampling within highly eroded and undisturbed hillslopes to map spatial variation in depth to the argillic horizon. In undisturbed hillslopes, the argillic horizon was relatively parallel to the surface while in eroded hillslopes depth to the argillic was shallower upslope and deeper in lower slope positions. These spatially explicit hillslope data were used to parameterize a HYDRUS 2-D model and outflows at the lower slope were compared to the conventional parallel depth model.

Citation

Ryland, Rachel, David Radcliffe, Daniel Markewitz, and Aaron Thompson (2017): A HYDRUS 2D evaluation of altered depths to the argillic horizon due to erosion: What impacts on hillslope interflow?. Proceedings of the 2017 Georgia Water Resources Conference.