Date of Graduation

7-2021

Document Type

Thesis

Degree Name

Master of Science in Geology (MS)

Degree Level

Graduate

Department

Geosciences

Advisor/Mentor

John Shaw

Committee Member

Glenn Sharman

Second Committee Member

Mac McGilvery

Keywords

Basin Shape, Delta, Mississippi Delta, Numerical Modeling, Sedimentary Geology

Abstract

The distributary channel network morphology on deltas is important for the delta evolution study because channels are the primary conduit for carrying and distributing water, sediment, and nutrients to the coast. Numerical models of river deltas and their channels have improved remarkably over the past two decades. However, the long-term (millennial scale) simulation of real delta systems remains rare. Here, we attempt to reconstruct the Lafourche Delta channel network, active 1600-600 years before present, with a simple numerical model (Moving Boundary Model for Distributary Network, MB_DCN). The model was run for 9 possible paleo basin boundaries and 6 water discharge parameterizations based on the Mississippi River discharge rate. In each case, the model produced distinguishing channel characteristics including a channel network geometry, progradation rate, and number of bifurcation. For the appropriate basin shapes, reasonable water discharge and common sediment transport parameters, MB_DCN produced a channel network that resembles the Lafourche Delta channel network morphology and progradation rates. The sediment transport nonlinearity appears to set the network geometry, the basin boundary constrains channel direction, and water discharge controls channel tip growth rate. The model produces a millennial scale channel evolution on delta, despite its simplicity.

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