HR: 1330h
AN: H52A-1170    [PDF]
TI: Channel Recovery Following Dam Removal: Lessons From Three Historic Dam Removals of the Middle Atlantic Piedmont
AU: * Pizzuto, J E
EM: pizzuto@udel.edu
AF: University of Delaware, Geology Department, 101 Penny Hall, Newark, DE 19716 United States
AU: Skalak, K J
EM: kskalak@udel.edu
AF: University of Delaware, Geology Department, 101 Penny Hall, Newark, DE 19716 United States
AU: Brown, R
EM: brown@acnatsci.org
AF: Patrick Center for Environmental Research, Academy of Natural Sciences 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103 United States
AU: Tomlinson, J
EM: 83375@udel.edu
AF: University of Delaware, Geology Department, 101 Penny Hall, Newark, DE 19716 United States
AU: Moskalski, S
EM: moskalsk@udel.edu
AF: University of Delaware, Geology Department, 101 Penny Hall, Newark, DE 19716 United States
AB: To determine the rates and processes of channel recovery following dam removal, we studied 3 sites along Muddy Creek in southeastern Pennsylvania. Garthridge Dam, 12.2 m high and located the farthest downstream, was breached in 1933. Highrock Dam, 1.8 m high and located the farthest upstream, was breached in 1972. Castle Fin Dam, 3.1 m high, was removed in 1997. We surveyed the longitudinal profile and channel cross-sections upstream of the former dam site. We also sampled the bed material and mapped floodplain and channel deposits. Undammed reaches far upstream were used as controls. At all sites, laminated muddy reservoir deposits are still preserved as terraces up to 5 m high bordering the channel. These deposits are persistent and will likely remain in place for decades, if not centuries. In addition, these deposits are a preferred habitat for exotic plant species, which had exceptionally high cover values at all three sites. At Castle Fin, laminated muddy reservoir deposits underlie the channel bed, indicating that the channel has not incised to its predam elevation after 5 years. At the other sites, vertical incision has completely removed fine-grained reservoir deposits from beneath the channel. Bed material is finer grained near the former dam site than at the control reaches at all the sites, and the water surface slope is higher near the former dam site than at the control reaches. These data suggest that, even after many years, channels above locations of removed dams are noticeably different from nearby control reaches, possibly indicating that complete recovery from dam removal is an inherently slow process.
DE: 1800 HYDROLOGY
DE: 1803 Anthropogenic effects
DE: 1824 Geomorphology (1625)
SC: Hydrology [H]
MN: 2003 Fall Meeting