Effects of Upstream River Flow Regulation on the Annual Low Flow Magnitude in the Savannah River at Augusta, Georgia, USA

The present paper investigates the effects of flow regulation on low flow conditions in the Savannah River at Augusta, GA before and after the construction of major dams and reservoirs. The Savannah River flow upstream of Augusta, GA is regulated by the operation of three large federal multipurpose projects: Hartwell Dam, Richard B. Russell Dam, and J. Strom Thurmond (also known as Clarks Hill) Dam. During low-flow periods, the operation of the dams is controlled by the drought contingency plan of the Savannah River basin. Analyses of low flow statistics at the Augusta water level gauge indicate that trends in the low flow volumes and frequencies are significantly modified after the construction of the dams. Although water level data collected before and after the construction of the dams show homogeneous properties, the data show considerable heterogeneity because of flow regulation when the full data record is considered. Low flow statistics for the period after the construction of all three dams show the Log Pearson Type 3 distribution to be the most suitable. Flow distribution also shows a considerable increase in annual minimum daily-mean flow rate compared to that prior to the construction of the dams.