Compilation of Data on the Middle Savannah River for the Analysis of Sub-Daily Flow Variation

The Nature Conservancy (TNC) has been working with the U.S. Fish and Wildlife Service (USFWS), the U.S Army Corps of Engineers Savannah District (USACE - Savannah) and other stakeholders on environmental flow recommendations for the Savannah River since May 2002 and have recently (2015) updated the environmental flow recommendations from 2003. Analysis of the flow data revealed a large amount of flow variability on sub-daily basis in the reach of the Savannah River from the Augusta Shoal downstream to the New Savannah Lock and Dam. The sub-daily flow variability affects sustaining suitable habitat during critical periods to promote fish spawning of robust redhorse, shad, and Atlantic sturgeon. The cause of the flow variability is hypothesized to be a result of the interaction of flow releases by two upstream hydroelectric facilities (Strom Thurmond Lake and Stevens Creek Hydroelectric Facility [Stevens Creek]) and backwater conditions. An important goal of the USACE Sustainable River Program (SRP) is to improve the health of rivers by changing the operations of reservoirs. Important tasks to meet this goal include work to: improve the understanding of existing hydrologic, ecological and socio-economic conditions at project sites; to refine environmental flow needs; and improve reservoir operations.
To better understand how these upstream flow releases interact, a time-series database was compiled to evaluate the flows releases and the downstream variability. Stream temperature was included in the dataset because the sub-daily variability is more biologically critical during particular temperature ranges. Continuous monitoring data was obtained from the U.S. Geological Survey (USGS) and the USACE. The South Carolina Electric and Gas Company (SCE&G) provided data on the daily operation for Stevens Creek. The data were organized in monthly workbooks with one spreadsheet per day of the month. Scripts were written to parse the data from the various workbooks and spreadsheets into a continuous time series of hourly flow releases from Stevens Creek. The period for the compiled data set is January 1, 2011 to December 31, 2015. Time-series of time derivatives of daily change in flow at the USGS gaging station was computed. The measured and computed time-series data were compiled into a data viewer to facilitate the interrogation of the flow and temperature data and to visualize the interaction of the hydropower releases on downstream flow rates.