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MORPHOLOGICAL FILTERS IN FLOODPLAIN FOR DEMEXTRACTED DATA – USING MINIMUM BOUNDING CIRCLE &
YOUDEN INDEX

Peng Jin

Submitted to the faculty of the University Graduate School
in partial fulfillment of the requirements
for the degree of
Master of Science
in the Department of Geography,
Indiana University
April 2017

Accepted by the Graduate Faculty, Indiana University, in partial
fulfillment of the requirements for the degree of Master of Science.

Master’s Thesis Committee

___________________________
Daniel P. Johnson Ph.D., Chair

___________________________
Frederick L. Bein Ph.D.

___________________________
Vijay O Lulla Ph.D.

ii

ACKNOWLEDGMENTS
This research was supported by IUPUI – POLIS Center and IUPUI – Department
of Geography. I would like to show my gratitude to the POLIS Center for sharing
their data with us. I am sincerely thankful to my colleague Jeffery Ashby for using
his classification methods to produce our research data. I would also like to take
this opportunity to express my sincere gratitude to my advisor Daniel P. Johnson
Ph.D. (Chair) for his continued support throughout my research, his patience,
enthusiasm, and immense knowledge. I am also immensely grateful to my thesis
committee: Frederick L. Bein Ph.D. and Vijay O Lulla Ph.D. for providing their
insight and expertise that greatly assisted my research.

iii

Peng Jin
MORPHOLOGICAL FILTERS ON DEM-EXTRACTED DATA – USING MINIMUM
BOUNDING CIRCLE & YOUDEN INDEX
Floods are one of the worst disasters in the United States. Each year, the
government allocates a tremendous amount of manpower and money on flood
prevention initiatives. As the first defense line, levees provide protection from
temporary flooding (Makhdoom, 2013). These embankments are broadly classified
according to the areas they protect, which could either be urban or agricultural
levees within floodplains. In the U.S., most of the levees are handled by
government agencies such as the U.S. Army Corps of Engineers and Federal
Emergency Management Services. On the other hand, non-levee embankments
created by individual farmers (Olson & Morton, 2013) or naturally formed leveelike structures may not be in the government database. The initial purpose of this
research was to assist Polis center on the “Mapping of Non-Levee Embankments
in the Indiana” project. The non-levee embankments are not certified or engineered
levee-like structures. They, therefore, impose lateral constraints on flood flows,
reducing the floodplain storage capacity and increasing the flood velocity. These
non-levee embankments can cause stream erosion and downstream flooding.
Therefore, it is important to know the locations of these features. The first part of
the proposed method adapted the Empirical Bayesian theorem and the low pass
filter techniques to extract elevated linear features from LiDAR elevation data –
Digital Elevation Model (DEM). The second part of the proposed methods
combined the Minimum Bounding Circle (MBC) method and the Youden Index to
locate the optimal threshold value that can be used to determine whether the
extracted features are levee-like structures. The focus of this study is not only
limited to artificial levee-like structures, but also takes the natural levees, or any
potential levee-like structures into account because this study assumes all
embankments play important roles during flood events.

Daniel P. Johnson Ph.D

iv

TABLE OF CONTENTS

List of Figures ....................................................................................................... vi
List of Abbreviations ............................................................................................ vii
Introduction ........................................................................................................... 1
Levee ......................................................................................................... 1
Digital Elevation Model .............................................................................. 2
Imagery Noise ........................................................................................... 3
Purpose ..................................................................................................... 3
Literature Review.................................................................................................. 5
Data Source.......................................................................................................... 9
Workflow ............................................................................................................. 14
Methodology ....................................................................................................... 15
Imagery Classification .............................................................................. 15
Minimum Bounding Circle ........................................................................ 16
Youden Index & ROC .............................................................................. 19
Result ................................................................................................................. 22
Discussion .......................................................................................................... 33
Conclusion .......................................................................................................... 35
Reference ........................................................................................................... 36
Curriculum Vitae

v

List of Figures
Figure 1: Natural Levee and Artificial Levee ......................................................... 2
Figure 2: Indiana State Overview Map ............................................................... 10
Figure 3a: Pulaski County DEM map.................................................................. 11
Figure 3b: Lawrence County DEM map.............................................................. 12
Figure 3c: Morgan County ...