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

Abstract

Sediment bodies produced during historical periods of human land use, sometimes referred to as legacy sediment, may be found in various locations within drainage basins, and potentially remobilized by hydrogeomorphic processes accompanying land use change. The amounts and locations of stored legacy sediment can be significant factors in modern drainage basin function and should be accounted for when possible. In this study, late nineteenth-century erosion and sediment storage were investigated and used to construct approximate sediment budgets for two small Blue Ridge Mountain drainage basins in North Carolina (USA). Erosion was quantified using a distributed implementation of the Universal Soil Loss Equation (USLE), and calibrated on the separate bases of soil profile truncation data and recent published rates for long-term erosion in the region. Sediment yield information was reconstructed from pond sediments trapped behind a mill dam. Alluvial sediment storage was quantified using field studies of streambank and floodplain sediment profiles and digital elevation data. Colluvial storage was calculated as a residual in the sediment budget, and further evaluated using soil profile studies of footslope deposits, and soil survey maps. The proportions of erosion accounted for by the different budget terms in the most reliable budget are: 28% sediment yield (i.e., a sediment delivery ratio of 0.28), 69% colluvial storage, and 3% alluvial storage. Blue Ridge basins with low levels of ground disturbance erode like Piedmont basins at high levels of ground disturbance, primarily due to higher slope angles. Sediment delivery ratio is high relative to those given for much larger basins in the adjacent and more frequently studied Piedmont province, and generally in accordance with published sediment delivery curves that reflect higher hydrogeomorphic connectivities within smaller basins. Low values for alluvial storage in Blue Ridge basins may be explained by high sediment transport within steep channels. Colluvial 3 storage values have high uncertainties because of the well known problem of error accumulation in residual budget terms. Field data on colluvial deposits reported here are not sufficient to correct for this problem, and in general, the acquisition of accurate field data on historical colluviation remains an important methodological issue in historical sediment budgeting.

The importance of and need for rapid hydrologic assessments in Latin America

“…Synoptic studies and chemical comparisons are commonly reported in the literature of mountainous regions in temperate systems (e.g., Inyan & Williams, ; Mast, Murphy, Clow, Penn, & Sexstone, ; Royall & Kennedy, ), but they have been rarely reported for mountainous streams in tropical regions. Although monitoring data are considered the base of management decisions in the tropics (Castello et al, ), the lack of consistent monitoring programmes often forces researchers and decision makers to use surrogates for water quality in high‐elevation regions (including satellite imagery as a measure of erosion and soil loss [Wantzen & Mol, ] and percent ground cover as a proxy for water quality states [Oyague Passuni & Maldonado Fonkén, ]).…”

Seasonal Precipitation Variability and Gully Erosion in Southeastern USA

“…Land cover change due to logging and conversion of forest to crop and pasture was linked to nineteenth-century European settlement in the southern Blue Ridge Mountains and Appalachian hillslopes [6][7][8][9]. Harvesting on the steep Appalachian hillslopes has been identified as one potential cause of soil erosion [10].…”

Geological classification and mapping of technogenic (artificial) ground: A comparative analysis

“…May as it be, the research on anthropogenic alluvium (also named legacy sediments, postsettlement alluvium, induced anthropic formations, technogenic-sedimentary deposits or technogenic wash) has developed significantly in several parts of the world (e.g. BORJA BARRERA 1993, TRIMBLE 2008, BROWN et al 2013, JAMES 2013, RICHARDSON et al 2014, DONOVAN et al 2015, JORDAN et al 2016, ROYALL & KENNEDY 2016, LU et al 2017, GRIMLEY et al 2017, JAMES 2017, fully justifying the inclusion of these anthropogenic sedimentary deposits in the classification scheme. 3 CLASSIFICATION OF TECHNOGENIC DEPOSITS BY OLIVEIRA (1990), ENHANCED BY PELOGGIA (1999) Based on the concept of technogenic deposit proposed by CHEMEKOV (1983), OLIVEIRA (1990) innovated by suggesting a general classification of these grounds into three basic types: constructed, induced and modified.…”