Hurricanes and Disaster Declarations
HURRICANES AND DISASTER DECLARATIONS:
A STATISTICAL ANALYSIS
By
VERONICA REOTT
A SENIOR RESEARCH PAPER PRESENTED TO THE DEPARTMENT OF MATHEMATICS AND COMPUTER SCIENCE OF STETSON UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF BACHELOR OF SCIENCE
STETSON UNIVERSITY
2005
ACKNOWLEDGEMENTS
I would like to acknowledge all of my mathematics professors at Stetson University, especially Dr. Will Miles who has advised, encouraged, and believed in me.
I would also like to acknowledge Joanne Spano, who has helped me so very much throughout this whole endeavor and without whose acquaintance I may never have come up with this idea.
TABLE OF CONTENTS
ACKNOWLEDGEMENTS ------2
LIST OF TABLES------4
LIST OF FIGURES------5
ABSTRACT------6
CHAPTERS
1. INTRODUCTION------7
2. BACKGROUND------10
3. SIMPLE LINEAR REGRESSIONS------15
3.1. Distance from coast------18
3.2. Total Rainfall------22
3.3. Maximum sustained wind speed------24
3.4. Distance from eye------26
3.5. Distance from site of landfall------28
3.6. Overall speed------31
3.7. Discussion------32
4. MULTIPLE REGRESSIONS------36
4.1 Techniques------36
4.1.1 Use of Matrices------36
4.1.2 Data collection and missing data------38
4.2 Multiple regression models------39
5. RESULTS------42
5.1 Choosing the correct model------42
5.2 Testing the model------43
5.2.1 Multicollinearity------45
5.3 Finalizing------46
SUMMARY------47
APPENDICES------49
A: Probability Tables------49
B: FEMA Figures------52
REFERENCES------48
LIST OF TABLES
1)Table A.1:Distance from coast stats------49
2)Table 3.1.1:Distance from coast ANOVA------21
3)Table A.2:Total rainfall stats ------49
4)Table 3.2.1:Total rainfall ANOVA------23
5)Table A.3:Max wind speed stats ------50
6)Table 3.3.1:Max wind speed ANOVA------25
7)Table A.4:Distance from eye stats------50
8)Table 3.4.1:Distance from eye ANOVA------28
9)Table A.5:Distance from site of landfall stats ------51
10)Table 3.5.1:Distance from site of landfall ANOVA------30
11)Table A.6:Overall speed stats ------51
12)Table 3.6.1:Overall speed ANOVA------32
13)Table 3.7.1 Distance from coast linear model ANOVA------34
14)Table 4.2.1 Multiple regression ANOVA information and F test scores------40
15)Table 5.2.2 Coefficient comparison test for multicollinearity------46
LIST OF FIGURES
1)Figure 3.1.1:Distance from coast observed values and exponential model ------20
2)Figure 3.1.2:Distance from coast observed values vs predicted values------21
3)Figure 3.2.1: Total Rainfall observed values and logarithmic model------22
4)Figure 3.2.2: Total Rainfall predicted versus observed values------23
5)Figure 3.3.1: Max sustained wind speed observed values and logarithmic model----24
6)Figure 3.3.2 Max sustained wind speed predicted versus observed values------25
7)Figure 3.4.1:Distance from eye observed values and exponential model------27
8)Figure 3.4.2:Distance from eye observed values vs predicted values------27
9)Figure 3.5.1:Distance from site of landfall observed values and exponential model- 29
10)Figure 3.5.2:Distancefrom site of landfall observed values vs predicted values------30
11)Figure 3.6.1: Overall speed observed values and linear model------31
12)Figure 3.7.1. Residuals example------34
13)Figure B.1: Saffir-Simpson scale------52
14)Figure B.2: FEMA Regions------53
15)Figures B.3-B.5: Declared counties examples------54-56
14) Figure 5.2.1 Variance covariance matrix for multiple regression model------44
ABSTRACT
HURRICANES AND DISASTER DECLARATIONS: A STATISTICAL ANALYSIS
By
Veronica Reott
May 2005
Advisor: Dr. Will Miles
Department: Mathematics and Computer Science
This study will focus on selected hurricanes from the 1998 through 2004 hurricane seasons. Statistical analysis of overall speed of the hurricane, county by county quantities for maximum sustained wind speed, total quantity of rainfall, proximity to the eye, proximity to the coast and proximity to site of landfall determines a statistical correlation between these factors and which counties in the states of FEMA’s region IV are likely to be declared “disaster areas” by the governor. Each of the factors will be regressed individually and all will be regressed simultaneously to bring about a model whose input is a known or projected value for each of the aforementioned factors and the output is the probability that a county will be declared a disaster area.
CHAPTER 1
INTRODUCTION
Charley, Frances, Ivan and Jeanne are names that have recently become common place in most homes across Florida and the rest of the nation. These are not characters on the newest reality television show. They are not the names of politicians who have battled it out in this year’s elections. These are the names of deadly storms, hurricanes, which ravaged Florida from both coasts this hurricane season.
For as far back as this researcher can remember, Florida has been virtually invincible to hurricanes. Save hurricane Andrew in 1992, the count of hurricanes with landfall and damaging effects in Florida has been quite low in the past few decades. Each time there is a tropical depression or simply an area of low pressure out in the Atlantic somewhere, the meteorologists of the world put their heads (and computers) together. Four-day and seven-day possible path predictions are calculated and the local news weather forecasters do the best they can to prepare the viewers for the worst. Until this past hurricane season, their advice may or may not have been completely heeded. Floridians have gone through many hurricane scares when right at the last moment, the hurricane is pushed northward or back out into the Atlantic and Florida sees mild wind and rains and no landfall. It is no surprise that some may have come to view hurricane path predictions as the forecaster “crying wolf.” This kind of attitude was highly diminished during the 2004 hurricane season. Floridians were glued to their television sets (or radios for lack of power) for days on end, several weeks in a row, as new and ever more daunting weather systems arose that threatened their lives and their livelihoods.
The Federal Emergency Management Agency or FEMA is a governmental organization which “is tasked with responding to, planning for, recovering from and mitigating against disasters” (2). FEMA’s involvement in the response to and recovery from a catastrophic event officially begins when the damage from such an event reaches a level that is beyond the capabilities of the state to handle on its own. When the damage reaches this level, the governor of the state will request a “disaster declaration” from the president. This declaration, given county by county, sets into motion FEMA’s processes of assessment of the amount of federal aid that will be needed for each county and delivery of this aid to those in need. The aid given by FEMA comes in many forms.
The process by which FEMA provides assistance to victims of hurricanes in the state of Florida is the focus of this study. Aside from loss of life, the most devastating damage that can occur is the loss (complete or partial) of one’s home. Therefore, the specific type of aid that will be focused on in this study is Individual Assistance which is allocated by the Individuals and Households Program (IHP) department of FEMA.
The Individuals and Households Program is the department that an individual can contact in the case of a hurricane (or other disaster) to appeal for aid such as temporary housing, repairs to one’s home, replacement of lost articles and other types of individual assistance. The IHP uses a standard model for determining the amount of aid that will be needed in each county. This model, known as the Preliminary Damage Assessment (PDA), is based on the number of structures (homes, apartments, mobile homes) which were fully or partially damaged by the hurricane, the percentage of those likely to be insured, and the expected number of aid applications in each county. The dollar amount of federal and state aid that will be needed to assist individuals each county is given by this PDA.
Hurricane data from the 1998-2004 hurricane seasons such as the site of landfall and overall speed of each hurricane in conjunction with county by county averages of maximum sustained wind speed and quantity of rainfall, county by county values for proximity to eye and proximity to coast will be used in the statistical analyses. The probability that a county is declared given that it has certain values for the factors given above will be found. An example of the type of calculation that will be performed is to find the probability that a county will be declared a disaster area given that it is within 100 miles of the eye of the storm, or the probability that a county will be declared given that it experienced maximum wind speeds less than 74 miles per hour. These conditional probabilities will be found for different configurations of each of the factors listed above. They will be found for each of the counties affected in each state that was declared of FEMA’s region number four (See Figure B.2). Hypothesis tests and other tests of statistical correlation will be performed on this data to determine how crucial each of the factors is in determining the disaster declaration of the counties. This analysis lends itself to a model whose input would be the overall speed of the hurricane, the projected path, and rain band and wind speed band data. The surrounding counties that are statistically likely to be declared as disaster areas are the output.
CHAPTER 2
BACKGROUND
Hurricanes are some of the most devastating disasters and therefore the most costly. Hurricane Andrew alone cost FEMA $1.8 billion. This figure takes into account personal loss of people’s houses, cars, businesses and other personal damages they may have incurred as well as damage to public works such as roads, public and governmental facilities and the costs of restoration of Wildlife Management Areas (1). Damage from hurricanes is so severe because of the variety of destructive forces a hurricane entails. The high speed winds blow off roofs and blow trees into houses, the intense quantity of rainfall causes flooding during and after the storm. It is difficult for people to see that a hurricane is an important and necessary part of the earth on which they live, especially when it brings its destructive forces to their front door. But, hurricanes do have a very important role to play in the highly intricate workings of the atmosphere.
The movement of the atmosphere and the interaction between the air masses therein is a very detailed and specialized subject. There are two essential processes of the “global weather machine,” a radiative balance between the earth and the sun, and the transport of energy within the atmosphere around the surface of the earth (5). The sun radiates energy constantly towards the earth at differing, visible and invisible wavelengths. At the same time, the earth, including land, ocean and air, is radiating energy back into space. Over time this influx and out flux of energy balance out. The poles of the earth are tilted away from the sun for much of the year. Therefore, very little energy is radiating into the earth in these areas while the land, ocean and air at the poles are still radiating energy out into space. The balance of energy coming in and energy leaving the earth, therefore, must be kept by the transport of energy within the earth’s atmosphere from the equator, where the sun’s radiation of energy is the most intense, towards the poles where much energy is lost but very little gained. This transportation of energy “drives the global atmospheric and oceanic circulation during the year” (5).
Hurricanes, also known as typhoons or cyclones in different parts of the earth, are very important in the transfer of large amounts of energy from the center latitudes towards the poles. They begin as depressions along the intertropical convergence zone, the area around 20 degrees south to 20 degrees north latitude of the equator, where the sun beats down upon the earth with greatest intensity. The depressions that become hurricanes show a sharp decrease in pressure at the center accompanying an increase in wind speed and circular cloud formation about 30-60 kilometers from the center. These storms pick up energy from the heat in the water around them. Once the wind speeds have reached 120 kilometers per hour, the storm is labeled a hurricane. Hurricanes grow in size and intensity quickly. The more organized the center, the more intense the hurricane.
“They may speed up, slow down, or even stop for a while to build up strength. As it travels across the ocean, a hurricane can pick up as much as two billion tons of water a day through evaporation and sea sprays.” (6)
The path of an Atlantic hurricane is essentially a northward movement and also a movement towards warmer waters whenever possible. A hurricane is an intensely destructive atmospheric creation that occurs because of the necessity of the atmosphere to constantly transport energy from the equator towards the poles. Hurricanes, thus, have an actual physical responsibility in the functioning of the earth’s atmosphere.
While they help to keep things running smoothly on a global scale, hurricanes do definitely cause quite a few problems on the local scale. Luckily, the US government has developed agencies and programs which can help minimize the devastation caused by these monsters. FEMA was developed during the presidency of Jimmy Carter as a centralized unit to control the handling of emergencies and disasters including, of course, hurricanes. The Agency united the operations of the Federal Insurance Administration, the National Fire Prevention and Control Administration, the National Weather Service Community Preparedness Program, the Federal Preparedness Agency of the General Services Administration and the Federal Disaster Assistance Administration among others. In 2003 FEMA became a segment of the Department of Homeland Security.
When a hurricane is out in the Atlantic or in the Gulf and it looks as though it may strike Florida, law enforcement and emergency teams in the threatened cities and counties are on call, awaiting commands from higher authorities. They and the general populace are constantly informed about the decisions being made in the governor’s office and about what will be done in the case that the hurricane makes landfall on Florida’s approximately 1350 miles of general coastline. Shelters open up all over the state where people can seek refuge if they are concerned or if they need special assistance. The governor, when the situation seems unavoidable, will sign an executive order to place the state in a “state of emergency,” which directs each county to activate its Emergency Operations Center and its County Emergency Management Plan. At this point evacuations and curfews and other such procedures are put into effect according to the governor’s executive order. Emergency personnel are centralized in the areas of most risk to “protect the lives and property of persons in the threatened communities” (7).
Actions are being taken on a federal scale at this time as well. Since hurricanes can be tracked and their intensity is known in advance, FEMA is usually aware before landfall whether federal response is going to be necessary. No federal aid is specifically allowed before the presidential declaration but the
“DHS [Department of Homeland Security] can use limited predeclaration authorities to move Initial Response Resources (IRR) (critical goods typically needed in the immediate aftermath of a disaster)…and emergency teams closer to potentially affected areas. DHS also can activate essential command and control structures to lessen or avert the effects of a disaster and to improve the timeliness of disaster operations.”(8)
When the hurricane makes landfall, the local and state authorities do the best they can to keep everyone safe and informed. Once the damage levels are more than the state can handle, the governor requests a declaration of disaster from the president. After this declaration is given, FEMA’s emergency response takes full effect. Emergency Response Teams including members of the IHP division are set up in the affected areas and response and recovery procedures begin. This is the stage in which the Preliminary Damage Assessments are made. Data concerning the amount of households; be they single family, apartment homes or mobile home units which are fully or partially damaged is collected by assessors who fly over the affected areas in helicopters and tabulate the damage as they see it. This assessor, a member of the IHP division, then takes this data and applies the appropriate calculations to determine the amount of federal and state assistance needed in each area. Assistance is then given to those in need according to federal regulations.
The process of assisting those in need of aid following a hurricane is an intricate and interesting one. The beauty is in the logistics. There is an amazing amount of coordination that goes on between local, state, and federal governments in the event of a disaster such as a hurricane. Hurricanes not only help to coordinate the movements of gases in the system of the atmosphere, but they also force the coordination of movements of hundreds of people and entire agencies in the system of our government.
CHAPTER 3
CURRENT RESEARCH METHODS/DATA COLLECTION:
The Hurricanes that were used for this study are Hurricanes Charley, Frances, Ivan, and Jeanne from 2004, Isabel (2003), Isidore (2002), Allison (2001), Irene (1999), Floyd (1999), Dennis (1999), Bonnie (1998), Earl (1998), Mitch (1998), and Georges (1998). Very integral to the analyses in this study is the designation data for each county in each hurricane (examples: Figures B.3-B.5). The data for each of the factors (rainfall, wind speed, etcetera) has been collected from different sources such as the NWS, the NOAA, FEMA, and other sources such as private mapping and analysis centers. The probability of declaration data used in this project was found by physically measuring and counting. Maps of declared counties (examples: figures B.3-B.5) were used and, for example, a dot was placed directly on the site of landfall, concentric circles with radii increasing by 20 miles were drawn and the number of counties that were completely or partially inside each area were counted and separately tabulated. The number of counties that were declared disaster areas out of these tabulated values gives an upper and lower bound on the probability of declaration. The upper and lower bounds were averaged for each storm at each level (20 miles from landfall, 40 miles from eye, 6 inches of rain, etc.) to bring about the probability of declaration shown in the tables. The probabilities at each level were then averaged over all of the storms to give the mean. These means were used as the observed values, Yi, in the calculations to follow.