RELATING HILLSLOPE GULLY EROSION WITH SELECTED PRECIPITATION PARAMETERS

Gully erosion is a serious ecological issue where large quantities of sediment are transported down gradient causing significant damage to water quality, agriculture, aquatic, wetland, and riparian ecosystems. Gully erosion has been studied extensively at the lab scale and at the watershed scale, but less extensively at the intermediate hillslope scale. The objective of this study was to establish relationship between erosion rate and precipitation intensity, duration, and accumulation on hillslopes. The study was conducted on a hillslope severely affected by gully erosion located at the East Tennessee State University Valleybrook Research facility near Gray, TN. Erosion pins were installed in the gully channels, sidewalls, interfluves and delta area, weekly and storm event measurements of erosion pins were taken for a 15 week period. A weather station was installed to monitor precipitation at 5 minute intervals. Erosion data revealed that most of the deposition occurred in the gully deltas with both erosion and deposition occurring in the channels. These two areas also showed the most variability in terms of gully dynamics. Erosion was significantly correlated with precipitation duration, total precipitation, and intensity for the pins located in the deltas. This research shows that higher precipitation intensity events produce more erosion than lower precipitation events but total precipitation was more correlated with erosion. With this knowledge, land reclamation projects can be more effective and reasonable mitigation measures can be implemented to prevent further hillslope gully erosion.