Hydrology - Water Resources Report 35

Flow and Salinity Characteristics of the Santee River Estuary,
South Carolina

Brenda L. Hockensmith


A characterization of the relationships among streamflow, tide stage, and specific electrical conductance of water in the Santee River Estuary was the primary objective of this study. Conductivity, temperature, and stage data were collected from October 1996 through August 2002. Three stations, two on the South Santee River and one on the North Santee River, continuously recorded conductivity and temperature data. Stage data were also collected at each station. Longitudinal conductivity profiles of both distributaries were completed.

The flow characteristics for the study period were atypical compared to the flow characteristics since rediversion of the Santee River flow in 1985, based on computed streamflow at Jamestown and dam-release data reported by South Carolina Public Service Authority. Streamflow averaged 11,000 cfs (cubic feet per second) between October 1986 and August 2002. Between October 1997 and September 1998, it averaged 18,000 cfs, and between October 1998 and August 2002 average streamflow decreased to less than 3,700 cfs.

Regression analysis was used to quantify the relationships among streamflow, specific conductance, tide stage, and tide height. Strong correlations (R2 > 0.86) exist between streamflow at Jamestown and dam releases. Good correlations also were found with specific conductance between stations (0.72 < R2 < 0.95). The inverse relationship between dam releases and specific conductance at the stations was quantified. The relationship between dam releases and specific conductance along each river was quantified from longitudinal-profile data. The equations for these relationships can be used to estimate streamflow in the estuary from dam-release data, predict specific conductance at each station, and locate the saltwater interface in each distributary for a specified streamflow condition.

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