Date of Award

8-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Mathematical Sciences

Thesis Sponsor/Dissertation Chair/Project Chair

Jorge Lorenzo-Trueba

Committee Member

Eric Forgoston

Committee Member

Arup Mukherjee

Abstract

Fluvial deltas are composites of two primary sedimentary environments: a depositional fluvial region and an offshore region. The fluvial region is defined by two geomorphic moving boundaries: an alluvial-bedrock transition (ABT), which separates the sediment prism from the non-erodible bedrock basement, and the shoreline (SH), where the delta meets the ocean. The trajectories of these boundaries in time and space define the evolution of the shape of the sedimentary prism, and are often used as stratigraphic indicators, particularly in seismic studies, of changes in relative sea level and the identification of stratigraphic sequences. In order to better understand the relative role of sea-level variations, sediment supply, and basin geometry on the evolution of the ABT and SH, we develop a forward stratigraphic model that captures the dynamic behavior of the fluvial surface and treats the SH and ABT as moving boundaries (i.e., internal boundaries whose location must be determined as part of the solution to the overall morphological evolution problem). This forward model extends a numerical technique from heat transfer (i.e., enthalpy method), previously applied to the evolution of sedimentary basins, to account for sea-level variations, including eustatic sea-level cycles. In general, model results demonstrate the importance of the dynamics of the fluvial surface on the system response under a wide range of parameter values. In particular, model results suggest that time lags in the ABT response during sea-level cycles can result in river incision during the sea-level rise. These results can have important implications for the reconstruction of past sea-level changes from the stratigraphic record of sedimentary basins.

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