HR: 0800h
AN: H31A-1288    [Abstracts]
TI: Quantifying rates of soil erosion in a disequilibrium landscape
AU: * Reinhardt, L
EM: lreinhardt@ges.gla.ac.uk
AF: University of Memphis, Center for earthquake research and information, Memphis, TN 38152 United States
AU: Lang, A
EM: lang@liv.ac.uk
AF: University of Liverpool, Department of Geography, Liverpool, L69 7ZT United Kingdom
AU: Hoey, T
EM: thoey@ges.gla.ac.uk
AF: University of Glasgow, Department of Geographical and Earth Sciences, Glasgow, G12 8QQ United Kingdom
AB: The long and diverse history of land use in many agricultural parts of the World can only be understood by taking into account past erosion processes. The development of techniques employing terrestrial cosmogenic nuclides (TCNs) in fluvial sediment samples has revolutionised landscape denudation studies and potentially enables quantification of catchment scale soil erosion histories. However, the traditional use of TCNs requires that nuclide concentrations in soil are in equilibrium with the modern rate of soil erosion, and it is unclear whether such steady-state erosion rates may be estimated in anthropogenically disturbed catchments. We have developed a simple 1D numerical model to quantify the variability in steady-state erosion rates in soil due to anthropogenic disturbance in small river catchments during the Holocene. We have modelled a wide range of realistic soil erosion histories in both the Old and New World and found that anthropogenic disturbances frequently result in disequilibrium TCN concentrations in soil, precluding steady-state erosion rate estimation from TCN concentrations in modern river sediments. However, our model runs suggest that quasi-equilibrium erosion rates may have been attained at different times suggesting that order-of-magnitude erosion rates may be estimated from river terrace sediment deposited during such quasi-equilibrium periods. Moreover, our model runs suggest that minimum upstream erosion rates may be estimated from TCN concentrations in modern river sediment within many agricultural areas in both the New and Old World.
DE: 1213 Earth's interior: dynamics (1507, 7207, 7208, 8115, 8120)
DE: 1815 Erosion
DE: 1821 Floods
DE: 1824 Geomorphology: general (1625)
DE: 8122 Dynamics: gravity and tectonics
SC: Hydrology [H]
MN: Fall Meeting 2005