HR: 1340h
AN: OS23C-1335    [Abstracts]
TI: A Quantitative A/S Ratio for Predicting Shoreline Migration During Eustatic Base-Level Cycles
AU: * Paola, C
EM: cpaola@umn.edu
AF: St Anthony Falls Lab, University of Minnesota 2 3rd Ave SE, Minneapolis, MN 55414 United States
AU: Kim, W
EM: kimx0826@umn.edu
AF: St Anthony Falls Lab, University of Minnesota 2 3rd Ave SE, Minneapolis, MN 55414 United States
AU: Voller, V
EM: volle001@umn.edu
AF: St Anthony Falls Lab, University of Minnesota 2 3rd Ave SE, Minneapolis, MN 55414 United States
AU: Swenson, J
EM: jswenso2@d.umn.edu
AF: Department of Geology & Geophysics, University of Minnesota Duluth, Duluth, MN 55812 United States
AB: The ratio of accommodation to sediment supply (A/S) is commonly invoked in explaining shoreline response to base-level variation. We develop a quantitative shoreline-migration equation based on mass conservation at the shoreline. This relation can be recast in the form of a ratio that includes accommodation and sediment supply, along with several other effects including variation in the length of the marine deposystem, fluvial sediment storage, and spatial variation in subsidence. Ignoring the additional terms yields a quantitative A/S ratio that can be used for approximate shoreline prediction. The general shoreline equation accurately predicts observed shoreline variation in a controlled experiment for which the only externally imposed variable was base-level variation on two time scales, applied singly and then superimposed. In most field settings it would be difficult to obtain the data needed to constrain all the terms in the predictive equation. We measure the degradation of the accuracy of the predicted shoreline dynamics as we reduce the amount of data available by replacing observed time variation of successive terms in the equation with their mean values. By this measure, base level is the most important variable in predicting shoreline migration, followed in turn by sediment supply at the shoreline, geometry of the foreset, and the average subsidence rate across the foreset.
DE: 8105 Continental margins and sedimentary basins
DE: 4558 Sediment transport
DE: 3022 Marine sediments--processes and transport
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting