Date of Award

2010

Document Type

Honors Thesis (Open Access)

Department

Colby College. Geology Dept.

Advisor(s)

Robert A. Gastaldo

Second Advisor

Arthur C. Trembanis

Third Advisor

Bruce F. Rueger

Abstract

A MATLAB-based 2-Dimensional Fast Fourier Transform spectral analysis is developed and tested for its applicability to bedform morphology and hydrodynamic data from a hydrodynamically complex field site. The aspects of the procedure tested are (1) the use of an 8 sub-region arrangement for analysis versus five other arrangements, (2) the procedure for averaging the wavelength-and-orientation outputs from each sub-region to produce a single representative value for each image, (3) methods for eliminating and/or filtering poor quality data, and (4) the procedural steps in the spectral analysis that can appropriately incorporate automation versus manual involvement and interpretation. The automated technique is limited in its ability to adapt to the dynamic data set, and recommendations towards different procedures are made for future studies intending to use similar spectral analysis tools. Most notably, the applicability of the spectral analysis is limited by the bedform morphology and hydrodynamic conditions, requiring preliminary study of data sets prior to analysis by a 2D FFT program.

Keywords

sand ripple, coastal geology, fourier transform, matlab, rotary sonar, image processing

Click below to download supplemental content.

HEN AND CHICKENS BACKGROUND BIMODAL.mov (22746 kB)
Appendix I sand ripple morphology movie: background hydrodynamics

HEN AND CHICKENS STORM.mov (38326 kB)
Appendix I sand ripple morphology movie: storm conditions

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