Crago, Richard, Civil and Environmental Engineering, Bucknell University, 701 Moore Avenue, Lewisburg, PA, 17837, rcrago@bucknell.edu.
Aircraft-based LIDAR instruments were used in 2006 and 2017 to develop DEMs with horizontal resolution of 1 m. Both DEMS covered the entire Muncy Creek watershed in north-central Pennsylvania. In 2011, Tropical Storm Lee caused record flooding and significant reconfiguration of flow paths. The average difference E (a possible Erosion index) between elevations in 2006 and 2017 along a reach might indicate significant erosion (positive E) or deposition (negative E) in a reach. The stream power index SPI=A*S (where A is the watershed area contributing to flow in the reach and S is the average reach slope) is a well-known index predicting the likelihood and amount of sediment transported in a reach. If SPI increases with downstream distance (s) in a particular reach [that is, d(SPI)/ds>0], erosion might be expected, and vice versa for deposition. The research included all reaches in the watershed with areas greater than 10 hectares. Across the watershed, reaches with d(SPI)/ds>0 have histograms of reach-average E shifted to the right compared to reaches with decreasing SPI, as expected, but d(SPI)/ds and E are nevertheless poor predictors of each other. Small flow paths favored channel erosion (E>0) while large paths favored deposition (E<0). Mapped differences between 2006 and 2017 DEMs showed that stream channels tended to straighten between 2006 and 2017, in line with the observations of Kochel et al. (2015).
Muncy Creek, sediment, erosion, Stream Power Index