TY - JOUR T1 - A southeastern piedmont watershed sediment budget: Evidence for a multi-millennial agricultural legacy JF - Journal of Soil and Water Conservation SP - 298 LP - 310 VL - 60 IS - 6 AU - C.R. Jackson AU - J.K. Martin AU - D.S. Leigh AU - L.T. West Y1 - 2005/11/01 UR - http://www.jswconline.org/content/60/6/298.abstract N2 - A sediment budget was developed for a representative rural southeastern Piedmont watershed to estimate the relative importance of various sediment sources, particularly the contribution of agricultural sediments introduced to stream systems during the cotton-farming era (approximately 1820 to 1930 A.D.). The Murder Creek basin containing Monticello, Georgia was chosen because: 1) forestry and agriculture were and continue to be dominant land uses; 2) a U.S. Geological Survey (USGS) gage provided flow and suspended sediment records; and 3) the creek discharges into the Lake Sinclair reservoir (constructed 1949 to 1953), which could be used as a bedload sediment trap. Sediment rating curves, reservoir sediment deposition, and the Water Erosion Prediction Project (WEPP) and Universal Soil Loss Equation (USLE) erosion models were used to estimate suspended sediment export, bedload export, unpaved road erosion, and other surface erosion, respectively. Depths of historical agricultural sediment deposits were measured in stream cutbanks and floodplain auger holes. Historical row-crop agriculture led to floodplain deposition of a nearly-uniform 1.6 m (5.3 ft) of sediment, equivalent to 12.2 cm (0.40 ft) of topsoil over the watershed. The mass of cotton-farming sediments in valley storage was extremely large compared to current sediment export rates. At present sediment export rates, it would take six to ten millennia to remove all of the cotton-farming sediment in storage. This study suggests that the unstable streambanks, mobile sandy streambeds, and turbid conditions characteristic of modern Piedmont streams are largely a legacy of poor farming practices in the late 1800s and early 1900s. Estimated sediment exports exceed estimates of current inputs, and floodplain accretion rates and streambank conditions suggest streams have been in a state of net sediment export over the last 50 years. ER -