Nineteenth-century sediment yields from the Southern Blue Ridge Mountains

Natural and human-induced prehistoric and historical soil erosion and landscape development in Southwestern Tennessee, USA

“…Despite substantial changes in both run-off and sediment delivery, the magnitude of historical river channel change is relatively small, compared to rates estimated for the Late Pleistocene and Holocene (Leigh, 2008). However, historical timber exploitation and agricultural cultivation had significant environmental impacts like hillslope erosion, gullying and badland formation in the uplands of eastern North America (Ashe, 1909;Bennett, 1939;Smith, 1983;Grissinger and Murphey, 1984b;Magilligan and Stamp, 1997;Hyatt and Gilbert, 2000;Ambers et al, 2006;Kennedy, 2013). In many areas, soils on hillslopes were highly degraded or became permanently unusable for farming.…”

Historical erosion and sedimentation in two small watersheds of the southern Blue Ridge Mountains, North Carolina, USA

“…Sediment budgeting requires information on erosion, colluvial and alluvial sediment storage, and sediment yield. Sediment yield data for the high erosivity period are available for Rocky Cove (Kennedy, 2013), but not for Wolf Branch, and thus, sediment budgeting is only strictly possible for Rocky Cove. To facilitate comparison and discussion, we calculate the Wolf Branch sediment budget using an estimate of sediment yield equal to Wolf Branch USLE erosion multiplied by the directly quantifiable sediment delivery ratio for unadjusted USLE erosion at Rocky Cove.…”

“…Following the U.S. Civil War (1861-1865 CE) and until about 1900 CE, external demand for the area's timber increased the rate of land clearance, including for the first time by commercial loggers and the land was further and more densely settled in small communities. Four mill dams 10 were constructed at various times on mainstem Bent Creek, and one was constructed on the Rocky Cove tributary (Nesbitt, 1941;Royall, 2003;Kennedy, 2013 Nesbitt (1941) documented the land use history and general physical state of the land, including estimates of the severity of erosion, and the locations and acreages of different land uses over time from ground surveys and anecdotal accounts from former residents. Currently, the area is fully forested with oak (Quercus sp.…”

“…Thirty-five percent of the Rocky Cove watershed had been cleared for timber and farming by CE 1900, with 41% of that occurring after the Civil War in more gently sloping lowlands. Kennedy (2013) used pond sediments from Powell Mill (1880-1895 CE) in Rocky Cove to determine an average sediment yield for that period of 272 Mg km -2 y -1 (a value of 461 Mg km -2 y -1 without the 1.76 km 2 drainage area correction was erroneously reported in Kennedy, Assuming, as a first approximation, that peak nineteenth-century sediment yields at Wolf Branch were similar to those recorded in pond sediment from Rocky Cove (a quasi-ergodic space-fortime substitution) sediment yield would have dropped 89% between peak erosion and recovery phase periods. Although the space-for-time substitution may be erroneous, an order-ofmagnitude difference in sediment yields between cultivated and forested land is a reasonable assertion supported by much previous research (Wolman, 1967;Simmons, 1993;Royall, 2013).…”

“…The sediment comprising these terraces is reworked into channels by incremental fluvial scour and mass wasting of banks, but may be stored in these often expansive landforms for long periods (Jackson et al, 2005;James, 2013). Legacy sediment inputs can elevate watershed sediment yields decades to centuries or longer, following their initial emplacement atop older floodplain surfaces (Phillips, 1991;Meals et al, 2010;Kennedy, 2013;Brierley, 2010).…”