Hydrologic Modifications to the Lower Savannah River

Proceedings of the 2003 Georgia Water Resources Conference, held April 23-24, 2003, at the University of Georgia.This project uses existing flow and river morphology data to evaluate how the reservoir system and navigational dredging have altered the hydrology and form of the river over the last 50 years. This analysis is being conducted to support a joint Nature Conservancy – Corps of Engineers program to determine ways in which the management of dams can be changed to lessen the impact on natural systems, while continuing to provide benefits to people such as flood control, electricity generation, and recreation. Two USGS gages on the Savannah River below Augusta provide sufficient data to characterize the hydrology of the lower Savannah prior to and following installation of the Savannah River dams above Augusta. The operation of the dams has greatly reduced peak flows in the lower river. Under current operating rules, the 100-year flow is approximately the same magnitude as the pre-dam 2-year flow. River floodplain interactions probably have decreased commensurately. Conversely, 7-day low flows in the lower river have increased greatly since dam operations began. In addition to these hydrologic alterations, the lower Savannah has been directly modified through dredging and channelization to allow barge traffic to reach Augusta. Dredging and navigation efforts have been suspended for more than a decade due to a lack of demand for barge navigation. Approximately 26 miles or 13% of the river’s original length has been removed due to the creation of forty navigation cuts