CSDMS 2011 annual meeting poster Alex Burpee
Relationships between sediment caliber and delta shoreline geometry and stratigraphy
Rudy Slingerland, Penn State University University Park Pennsylvania, USA. sling@psu.edu
Abstract:
Recent morphodynamic modeling of non-uniform turbulent transport and deposition of sediment in a standing body of water devoid of tides and waves shows that sediment caliber plays a major role in determining the shapes, cumulative number of distributaries, and wetland areas of river-dominated deltas. In this study we introduce metrics for quantifying delta shoreline rugosity and foreset dip (clinoform) variability, and explore their variation with sediment caliber. Delta shoreline rugosity is calculated using the isoperimetric quotient, IP = 4 pi A / P2, where a circle has a value of one. Clinoform complexity is calculated using the uniformity test in circular statistics wherein clinoform dip direction uniformity is the sum of the deviations of dip azimuths from a theoretical uniform distribution. Analysis of fifteen simulated deltas shows that IP increases from 0.1 to 0.5 as the normalized shear stress for re-erosion of cohesive sediment, τn, increases from 0.65 to 1. Clinoform dip azimuth uniformity decreases from 300 to 130 with increasing τn. Preliminary analysis of data from outcrops of the Cretaceous Ferron Delta and ground penetrating radar data of the Pleistocene Weber and Brigham City Deltas are consistent with these trends. These results imply that changes in sediment caliber delivered to a deltaic coastal system will profoundly change its wetland area, bathymetric hypsometry, ecological function, and interior stratigraphy.
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