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Title: Temporal variations in baseflow for the Little River Experimental Watershed in South Georgia

item Bosch, David - Dave
item Williams, Randall
item Arnold, Jeffrey
item ALLEN, PETER - Baylor University

Submitted to: ASABE Annual International Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 12/27/2015
Publication Date: 7/17/2016
Citation: Bosch, D.D., Williams, R.G., Arnold, J.G., Allen, P. 2016. Temporal variations in baseflow for the Little River Experimental Watershed in South Georgia. [abstract] ASABE Annual International Meeting. 7/17-20/2016, Lake Buena Vista, Florida.

Interpretive Summary:

Technical Abstract: Hydrology is the driving force of sediment, nutrient, and pesticide movement. Separation of streamflow hydrographs into rapid surface runoff and baseflow can vastly improve our understanding of watershed processes. Data collected at the Little River Experimental Watershed (LREW) in the South Atlantic Coastal Plain of the U.S.A. (N31 26' 13", W83 35' 17”) from 1972 to 2014 were used for the analysis. Greater precipitation and lower evapotranspiration rates during the winter and spring months in the region create higher soil-moisture and greater aquifer recharge, increasing surface runoff responses and groundwater contributions to streamflow. Baseflow, the portion of streamflow coming from vadose zone and groundwater sources, makes up a large fraction of the streamflow during the winter and spring periods. Thus, baseflow is extremely important to sustaining streamflow throughout the Southeastern Coastal Plain. Increasing demands on groundwater, changes in land-use, and changes in precipitation patterns due to climate change are all expected to impact baseflow conditions and streamflow volume. The digital filter method used for separation of high and low frequency signals was used for baseflow separation. The two parameter Eckhart digital filter was used with a maximum baseflow index (BFImax) of 0.80 and an alpha value of 0.98. The baseflow index is the ratio of baseflow to total streamflow. Overall, baseflow was found to produce 54 % of annual streamflow, 13 % less than prior published results. Baseflow was the largest during the months from December through May (55-57 %) and the least during the months from June through November (42-47 %). Annual baseflow was found to decrease with increasing annual precipitation. Data indicated a decreasing long-term trend in annual precipitation, decreasing baseflow, and increasing variability. Data also indicate a shift in seasonal precipitation from the winter and spring to the summer and fall which is believed to contribute to reduced baseflow in the watershed.