RESEARCH

Field Scale River Delta Kinematics

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Bathymetry of Wax Lake Delta collected in August 2011

The striking variation in delta morphology observed on coastlines is the result of sedimentary processes that are active at the delta front; the region directly seaward of the shoreline. Aerial images do not capture the 3-Dimensional bathymetry of this region, and it remains largely unexplored. My work measures bathymetry, flow patterns, and sediment transport over the delta front to improve our understanding of distributary channel growth and the land building potential of river deltas.

Related Publications

Shaw, J.B., D. Mohrig, (2014), The importance of erosion in distributary channel network growth, Wax Lake Delta, Louisiana, USA, Geology, 42, 31-34, doi: 10.1130/G34751.1

Shaw, J. B., D. Mohrig, and S. K. Whitman (2013), The Morphology and Evolution of Channels on the Wax Lake Delta, J. Geophys. Res., 118, 1–22, doi:10.1002/jgrf.20123.

Edmonds, D. A., J. B. Shaw, and D. Mohrig (2011), Topset-dominated deltas: A new model for river delta stratigraphy, Geology, 39(12), 1175–1178, doi:10.1130/G32358.1.

Experimental River Delta Mechanics

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Snapshot from a delta experiment. The channels are ~1 cm wide and 6 cm long. Flow is from left to right.

To test hypotheses regarding river delta dynamics, I create physical experiments in the laboratory. I am running a set of experiments at the University of Wyoming to test the importance of low water surface slopes to channel evolution on large river deltas. The photograph to the right shows distributary channels in an experimental delta.

Find out more at the 2014 AGU Fall Meeting in San Francisco

Hurricane Washover Stratigraphy

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Describing and measuring a hurricane washover fan deposited by Hurricane Ike in 2008

Measuring sediment transport or barrier islands during a hurricane is presently impossible, so we very little information about what goes on in these destructive storms. However, washover fan stratigraphy provides a high resolution record of deposition during the storm.

Our analysis of fan stratigraphy and storm surge records allows us to make precise estimates of when overwash occured, as well as estimating sediment flux rates.

Shaw, J. B., Y. You, D. Mohrig, and G. Kocurek (2015), Tracking hurricane-generated storm surge with washover fan stratigraphy, Geology, 43(2), 127–130, doi:10.1130/G36460.1.

Stratigraphic Completeness of River Delta Shorelines

Stratigraphic completeness is a well-known measure of the fraction of time preserved within a stratigraphic column. A similar measure can be defined for the shoreline trajectory preserved in a stratigraphic section. We measure “shoreline completeness” for an experimental dataset, and find it to be larger than classical completeness as predicted by theory. This is collaborative research with scientists at the University of Wyoming and University of Colorado – Boulder.

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