Hydrologic Behavior of Gullies in the South Carolina Piedmont

The Piedmont region in the United States has been eroded and gullied due to deforestation and cultivation during the 1700 and 1800. Currently, a majority of these gullies are under forest vegetation and appear stable; however, neither the hydrology of these gullies, nor their sediment contribution to surface waters, has been quantified. This study instrumented eight gullies ranging in size from 36-90 m long, 2.4 to 9.5 m wide, and 0.9 to 3.0 m deep with weirs, stage recorders, and stormwater samplers to assess gully response to prescribed burning. Results from pre-burn data show that only four out of the eight gullies exhibit flow during storm events ranging up to 25.7 mm. Higher rainfall amounts, such as those achieved during hurricanes, may be needed to initiate flow in all gullies. This observation has implications for understanding gully re-activation and associated erosion.