Temporal variations in baseflow for the Little River experimental watershed in South Georgia, USA

Abstract

Study regionThe Little River Experimental Watershed (LREW) in the Southern Coastal Plain Major Land Resource Area of the U.S.A. (N31°28′54″, W83°35′03″). Study focusSeparation of streamflow hydrographs into rapid stormflow and baseflow can vastly improve our understanding of watershed processes. The two parameter Eckhardt digital filter method for separation of high and low frequency signals was used to estimate the portion of streamflow emanating from soil water and groundwater. The method requires estimation of two fitting parameters, BFImax and alpha (α). The baseflow index (BFI) is the ratio of baseflow volume to total streamflow volume. BFImax was set at 0.80 and α at 0.98. New hydrological insights for the regionBaseflow was found to produce 53% of annual streamflow. Stormflow was found to produce 47% of the annual streamflow. Baseflow was the greatest during the months from December through May (55–57%) and the least during the months from June through November (43–46%). Annual BFI was found to decrease with increasing annual precipitation, indicating that during high precipitation year’s saturation excess driven stormflow increases in the LREW. Hydrograph analysis indicated an average stormflow duration of seven days, typically extended by interflow in this watershed. These observed seasonal patterns can have a significant impact on regional agriculture as well as coastal estuaries that both rely heavily upon streamflow.