HR: 11:05h
AN: H41G-04    [PDF]
TI: Modeling River Networks in the Continental Shelf during Sea Level Cycles
AU: * Fagherazzi, S
EM: sergio@csit.fsu.edu
AF: Department of Geological Sciences and School of Computational Science & Information Technology Florida State University, Dirac Science Library Office 462 DSL, Tallahassee, FL 32306-4120 United StatesAU: Howard, A D
EM: alanh@virginia.edu
AF: Department of Environmental Sciences, University of Virginia, 291 McCormick Rd, P.O. Box 400123, Charlottesville, VA 22904-4123 United States
AU: Wiberg, P L
EM: pw3c@virginia.edu
AF: Department of Environmental Sciences, University of Virginia, 291 McCormick Rd, P.O. Box 400123, Charlottesville, VA 22904-4123 United States
AB: Several processes influence the development of fluvial networks in the continental shelf during sea level low stands. In order to understand the specific role of each process and quantify its influence on channel formation and incision, the Detachment Limited Model (DeLiM) (Howard, 1994) has been applied to several shelf configurations and with different sea-level curves. The computer model incorporates deltaic deposition on the continental shelf as well as sea-level oscillations and is parameterized with Virginia coastal plain data. Simulations show that the major factor controlling incision and channel development is the tendency of streams to reach an equilibrium (graded) configuration. If, for a given river discharge and shelf slope, the sediment load is less than that required to be at grade, channel incision will occur in the exposed shelf until the river long profile is in equilibrium with the current sea level (base level). The geometry and thickness of sediments deposited in deltas and estuaries have a minor influence on the total channel incision, but are of fundamental importance for the spatial development of the channel network. Model results show that the detailed structure of sea level oscillations is important for sediment redistribution and channel changes. Conceptual models that consider a mere succession of sea level high stands and low stands are oversimplified and miss the complex response of the system to gradual sea level oscillations. The initial shelf topography strongly characterizes the future network development. During the simulations the drainage network is initially strongly fragmented, but gradually becomes integrated through depression infilling and dissection of steep scarps. Finally the role of coastal processes is of crucial importance for sediment redistribution and shelf topography modification during sea-level oscillations.
UR: http://www.gly.fsu.edu/~fagherazzi
DE: 1625 Geomorphology and weathering (1824, 1886)
DE: 1815 Erosion and sedimentation
DE: 3309 Climatology (1620)
DE: 4556 Sea level variations
DE: 4558 Sediment transport
SC: Hydrology [H]
MN: 2003 Fall Meeting