Hydrology and Water Quality of Two First Order Forested Watersheds in Coastal South Carolina

Abstract Two first-order forested watersheds (WS 80 and WS 77) on poorly drained pine-hardwood stands in the South Carolina Coastal Plain have been monitored since mid-1960s to characterize the hydrology, water quality and vegetation dynamics. This study examines the flow and nutrient dynamics of these two watersheds using 13 years (1 969-76 and 1977-81) of data prior to Hurricane Hugo (1 989) and nearly 10 years (1 990-1 992, 1996-99, and 2003-06) immediately after Hugo. WS 80 remained as a control throughout the study period, whereas WS 77 underwent several treatments including prescribed burning, partial harvest, salvage logging and prescribed fire for red-cockaded woodpecker habitat management. Depending upon the antecedent moisture conditions, both the watersheds were highly responsive of rainfall events throughout the periods. Accordingly, annual outflows varied from 5% in 1981 to 59% in 1998 with an average of 22% of the annual precipitation for the control (WS 80) and from 9% in 2004 to 44% in 1991, with an average of 27% for the treatment watershed (WS 77). The coefficient of variation (COV) on WS 80 was higher (55%) compared to 36% for the WS 77. Annual rainfall variation was much lower (COV = 14%) than the