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Unit 4

Hurricanes in the Big AppleIn this unit, you will answer these questions • How do you determine hurricane probabilities for coastal cities?

• How does topography affect storm-surge risk?

• How do government agencies manage emergencies?

• Who is most at risk from hurricanes and why?

• How do you assess risks to the community’s infrastructure?

Land

sat imag

e, Space

Imag

ing

, Inc.

1997 Landsat 5 image of the New York City area. The hurricane risk to this area is real, and a cause of concern for emergency planners.

75

Data Detectives: Tropical Cyclones Unit 4 – Hurricanes in the Big AppleData Detectives: Tropical Cyclones Unit 4 – Hurricanes in the Big Apple

76

Data Detectives: Tropical Cyclones Unit 4 – Hurricanes in the Big Apple

Investigation 4.1

The physical factors of riskWhen most people think of cities that are at risk from hurricanes, they think of places like Miami, New Orleans, or maybe Charleston, South Carolina. Th ese cities have had either direct hits or very close calls with major hurricanes in recent memory, and seem to be threatened nearly every year. Few, if any, people associate New York City with hurricanes, believing that New York is too far north, or too far inland, to be in any real danger from a major hurricane.

Th e reality is that New York City was hit by major hurricanes in 1635, 1815, 1821, and 1893, and escaped with near misses in 1938, 1985 (Gloria), and 1999 (Floyd). Sooner or later, a “Big One” will make a direct hit on New York City, and because of characteristics of the shoreline and the distribution of people in the city, chances are good that the hurricane’s impact on the city will be severe.

How probable is a major strike?Hurricanes do strike New York City, although not as frequently as they hit coastal cities farther south. To begin, you will look at the probability that New York City will be hit by a tropical storm or hurricane during any given year. Th en you will determine the likelihood of New York City being hit by a major hurricane of H3 or higher.

Launch ArcView, locate and open the cyclones.apr fi le, and open the Hurricane Probability view.

Th is view shows the probability that any area in the Eastern United States will experience at least one tropical storm or hurricane during any given year. Next, you will determine the hurricane probability for New York City.

Activate the Hurricane Landfall Probability theme.

Using the Identify tool , click on New York City.

In the Identify Results window, read the Landfall Probability (%) fi eld to fi nd the hurricane probability for New York City.

1. What is the probability, in percent, that New York City will be hit by a

tropical storm or hurricane in any given year?

Close the Identify Results window.

What’s the risk?

Hurricane categoriesForecasters responsible for monitoring tropical cyclones have developed scales to describe a storm’s potential for destruction. The U.S. uses the Saffi r-Simpson Hurricane Scale. This scale ranks hurricanes in fi ve categories from 1 (the weakest) to 5 (the strongest). For further information on this topic, see the Reading in Unit 2.3.

To activate a theme, click on its name in the Table of Contents.

What's the risk? 77


2. According to Figure 1, what percentage of Atlantic tropical storms

between 1950 – 2005 were

a. minor (tropical storms and Category 1 and 2 hurricanes)?

b. major hurricanes (Category 3 or greater)?

Record your answers in Table 1.

Table 1 — Percentages of major and minor Atlantic tropical storms between 1950 – 2005

Storm category % of Atlantic storms in this category

Minor stormTropical storms, H1 and H2 tropical cyclones

Major stormH3 – H5 tropical cyclones

Th e probability you calculated in question 1 represents the likelihood that a tropical storm or hurricane will hit New York City in any given year. Table 1 illustrates the percentages of all Atlantic storms that are minor and major storms.

3. Determine the probability that New York City will be hit by a major storm (Category 3 or greater) in any given year. To fi nd this, multiply the percentages (as decimals) obtained in questions 1 and 2:

_____ (probability of a named storm hitting NYC in any year)

× _____ (% of major storms in Atlantic, as a decimal number)

= _____ (probability of a major storm hitting NYC in any year)

What is the “H” in H4?In the North Atlantic, tropical cyclones are called hurricanes, so “H” stands for Hurricane. Here, it means the same thing as category.

Figure 1. The percentage of tropical storms and hurricanes in the Atlantic Ocean between 1950 – 2005 that were classifi ed in each strength category.

Category 53 %

Category 48 %Tropical Storm

44 %

Category 123 %

Category 211 %

Category 311 %

Percentages as decimalsWhen writing percentages as decimals,

• Move the decimal point two places to the left.

• Drop the percent sign.

• Place a zero before the decimal point (if less than 100%).

Example: 37% = 0.37

78 What's the risk?


4. Determine the probability that New York City will be hit by a minor storm (Tropical Storm – Category 2 hurricane) in any given year. To fi nd this, multiply the percentages obtained in the fi rst two questions:

_____ (probability of a named storm hitting NYC in any year)

× _____ (% of minor storms in Atlantic, as a decimal number)

= _____ (probability of a minor storm hitting NYC in any year)

Th ese probabilities indicate the number of major and minor hurricanes, on average, that could hit New York City in any given year.

5. How many major hurricanes can New York City expect to get over the course of a century?

_____ (probability of a major storm hitting NYC in any year)

× _____ (number of years in a century)

= _____ (number of major storms hitting NYC in a century)

New York City’s hurricane history 6. Examine Figure 2. How many minor hurricanes aff ected or

threatened the New York City area in the 20th century? How many major hurricanes?

Minor hurricanes = ______

Major hurricanes = ______

NYC HurricaneHistory chartTo view this chart on your computer, click the Media Viewer button and choose NYC Hurricane History.

Figure . This chart shows hits by hurricanes on New York City and Long Island for the th century ( – ).

19001920

19401960

19802000H

urr

ica

ne

s m

ak

ing

lan

dfa

ll (a

nn

ua

l ave

rag

e)

Category 1 & 2

HurricanesCategory 3 – 5 (major)

Hurricanes

New York City and Long Island Hurricanes

1900 – 2005

20101990

19701910

19301950

19381944

Donna 1959

Carol 1953

Gloria 1985

What's the risk? 79


7. Based on Figure 2 and the hurricane probability you determined in question 5, how frequently do you think major hurricanes aff ect or threaten New York City? Explain.

Storm surgeTh e shape of the coastline can increase a hurricane’s impact on coastal towns and cities by concentrating the hurricane’s storm surge in a smaller area. As discussed in the sidebar at left , the shape of the coastline can amplify the eff ect of the storm surge by acting like a funnel, a pot, or a mirror.

Click the QuickLoad button , select the East Coast extent, and click OK.

Examine the Atlantic Coast, looking for sections of coastline with sharp changes in direction where a hurricane’s impact might be especially severe.

8. Locate three major bays or inlets that could trap water from a storm surge, and circle them using dashed lines on Map 1.

Map 1 — East Coast of the United States

The shape of a coastlinecan act like

a funnel, pushing large volumes of ocean water into smaller bays and inlets,

a pot, trapping ocean water in the bays and inlets and keeping it there, or

a mirror, refl ecting and bouncing the ocean water around in the bays and inlets.©2001 The SAGUARO Project and its licensors.All rights reserved.

NC

SC

GA

VA

WV

PA

FL

NY

ME

VT

NH

MA

CT

NJ

MD

80 What's the risk?


9. Find the place along the Atlantic Coast where the direction of the shoreline changes from generally north-south to generally east-west. Mark its location using a solid line on Map 1.

10. How might the shape and orientation of the coastline increase or decrease the impact of the storm surge?

New York City topographyAs you observed, the shape of the New York City coastline is unique. Th e right angle made by the coastlines of New Jersey and Long Island can funnel storm-surge waters into New York Harbor, particularly if the hurricane is approaching directly from the southeast.

Click the QuickLoad button , select the NYC Topography and Demographics view, and click OK.

Th is view shows a shaded relief (elevation) map of New York City. You will use it to study the eff ects of storm surge on the city in detail.

Figure 3 shows a satellite view of the area around New York City. Th e long island sticking out to the east is Long Island. Th e rectangle marks the approximate area shown in the map on your screen.

NA

SA/G

SFC/JP

L, MISR

Team

Figure 3. Image of Long Island and surrounding area, created by the Terra satellite.

What's the risk? 81


Pushing more water into the harbor is not necessarily a recipe for disaster. If the city was on a plateau 20 m above sea level, a 10-m surge of water would not have much of an eff ect. Unfortunately, only part of New York City sits on high ground, whereas the rest is very near sea level.

11. According to the elevation scales on the sides of the on-screen shaded relief map, what is the range of elevation values (lowest to highest) for the New York City area?

12. On Map 2, circle four areas with elevations lower than 5 m above sea level, and four areas with elevations higher than 10 m. Label each high area with an H and each low area with an L.

Map 2 — Shaded relief map of New York City and surrounding area

82 What's the risk?


Storm-surge riskStorm surge is a temporary change in sea level that occurs when strong winds pile ocean water into a bulge ahead of the hurricane (Figure 4). When it reaches the shallow waters at the coastline, the bulge has nowhere to go but upward and inland. Stronger winds produce higher storm surge.

Generally, as the height of the storm surge increases, the fl ooding extends farther inland. Next, you will explore how topography infl uences the predicted inundation, or fl ooding, of New York City.

Turn on the NYC Storm Surge theme.

Activate the NYC Storm Surge theme.

In this theme, darker shades of blue represent higher storm surges.

Click the Query Builder button .

To display only the areas fl ooded by a Category 1 storm surge, query the NYC Storm Surge theme for ([Category] = “Category 1”) as shown in steps 1 – 6:

If you have diffi culty entering the query statement correctly, refer to the QuickLoad Query described at left .

Do not close the Query Builder window, just move it aside to view the screen.

Th e light blue areas indicate the sections of coast that would be fl ooded by a Category 1 storm surge. (Hint: You may want to turn off the NYC Color Shaded Relief theme.)

Using the Identify tool , click within the blue storm-surge zone.

Read the maximum storm-surge height [Max Height (m)] and the total inundated area [Area (sq km)] in the Results window and record them in Table 2 on the following page.

QuickLoad Query • Click the QuickLoad Query

button, select the NYC Category 1 query, and click OK.

• Select the Display onlyFound Features mode.

• Click New.

Figure 4. For Atlantic storms like Hurricane Andrew shown above, the surge is usually located in the northeast quadrant, where the storm’s rotation and its forward motion add to produce the strongest winds.

Strongestwinds

Highest surge

Path

NA

SA

/GS

FC

To turn a theme on or off , click its checkbox in the Table of Contents.

Read query statement here as you enter it.

2) Double-click Field

3) Single-click Operator

4) Double-click or type Value

5) Choose Display Mode 6) Click New

1) Select Theme

What's the risk? 83


13. Complete Table 2 using the information you collect for the Category 1 storm surge.

Table 2 — New York City predicted storm-surge effects

Category Maximum storm-surge heightm

Total inundated area km2

1

2

3

4

Repeat this query procedure and record the information for Category 2, 3, and 4 storm surges in Table 2. You do not need to retype the entire query — just change the number in the query statement ([Category] = “Category X”) to the desired value.

When you have fi nished, close the Identify Results window.

Click Clear Filter in the Query Builder window.

Close the Query Builder window.

14. Graph the surge height versus the inundated areas from Table 2 on Graph 1.

Graph 1 — New York City storm-surge inundated areas

Notice that the inundated area does not increase uniformly from one category to the next. To understand why, you will examine topographic profi les at three diff erent coastal locations.

Turn on the Topographic Profi les theme.

Th e illustrations on the following page show the topographic profi les along the three lines shown on the map on your computer screen.

15. On each profi le, draw a horizontal line representing the surge height resulting from each of the Category 1, 2, 3, and 4 storm surges at that location. Use the surge heights you recorded in Table 2. Label these lines H1, H2, H3, and H4.

Topographic profi le — a cross-sectional view of the land surface. Imagine slicing through Earth, pulling the halves apart, and viewing one half from the side. The result is a topographic profi le. To make the land features easier to see, topographic profi les are usually “stretched” vertically — a process called vertical exaggeration.

84 What's the risk?


Graph 2 — Profi le A

Graph 3 — Profi le B

Graph 4 — Profi le C

8

7

65

4

3

2

1

0

9

Distance along profi le (m)S

urg

e h

eig

ht

(m)

– 500 20001000 30000 4000

Distance along profi le (m)

– 500 0 500 1000 1500

Su

rge

he

igh

t (m

)

87

6

5

4

3

2

10

9

Distance along profi le (m)– 500 0 30001000 2000 4000

87

6

543

2

10

9

Su

rge

he

igh

t (m

)

5000

What's the risk? 85


16. Explain how a large increase in the storm-surge height can cause only a small increase in the area fl ooded. Identify each profi le that shows an example of this.

17. Explain how a small increase in storm-surge height can cause a large increase in the area fl ooded. Identify each profi le that shows an example of this.

Turn off the Topographic Profi les theme.

Quit ArcView and do not save changes.

86 What's the risk?


Most countries, states, counties, and large cities, and even some businesses have agencies or offi ces that plan for what to do in the event of an emergency. Below are the addresses of several Web sites for emergency management agencies. Choose one or more and explore their sites to fi nd out how they prepare for a natural disaster such as a hurricane, what is done during the disaster, and how the impacts of a disaster are handled once the event has ended. Write a one-page summary of their emergency management plan for hurricanes.

FEMA (Federal Emergency Management Agency) Main page —

www.fema.gov

Hurricane page —

http://www.fema.gov/hazard/hurricane/hu_hazard.shtm

State emergency management agencies Delaware —

www.state.de.us/dema/information/nat_haz.shtml

Florida —

www.fl oridadisaster.org/bpr/emtools/severe/hurricanes.htm

Georgia —

http://www.gema.state.ga.us

Hawaii —

www.mothernature-hawaii.com/index.html

Louisiana —

www.loep.state.la.us/hurricanerelated/hurricaneindex.htm

Maine —

www.state.me.us/mema

Maryland —

www.mema.state.md.us

Massachusetts —

www.mass.gov/

New York —

www.semo.state.ny.us/PIO/HurricaneAwareness.cfm

Managing emergenciesInvestigation 4.2

Has a Web site moved and left no forwarding address?The SAGUARO Project maintains a list of current links for this module at

www.scieds.com/saguaro

Managing emergencies 87


South Carolina —

www.scemd.org/

Texas —

www.txdps.state.tx.us/dem/hurrindx.htm

Virginia —

www.vdem.state.va.us/prepare/

New York City Offi ce of Emergency ManagementHurricane preparedness page —

www.nyc.gov/html/oem/html/hazards/storms.shtml

Storm-surge information and hazard mapsEscambia County (Florida) animated storm surge —

www.escambia-emergency.com/Hurricane_Preparedness/surge map.htm

U.S. Army Corps of Engineers (hurricane-related links) —

http://chps.sam.usace.army.mil/USHESdata/HESHOME.htm

88 Managing emergencies


Earlier, you looked at some of the factors that aff ect hurricane risk and examined the likelihood of a major hurricane striking New York City. So far, however, we have ignored the most important factor — people. Th is investigation will explore the human element of hurricane risk.

Reverse demographics and hurricane riskIn many American cities, coastal areas are oft en favored by the wealthy as places to live. In New York City, however, the people in communities along the waterfronts oft en have lower income and education levels. Th is situation is called a reverse demographic, meaning that the social and economic distribution of people is the opposite of what is usually seen.

With respect to hurricanes, this reverse demographic makes an already dangerous situation even worse, because the areas most prone to fl ooding are inhabited by people who may be less

• Aware of the general dangers of hurricanes.

• Likely to be aware or informed of an approaching hurricane.

• Less mobile and therefore less able to quickly evacuate.

• Less likely to be able to aff ord fl ood insurance or recover fi nancially if a hurricane damages or destroys their home or workplace.

Demographic factorsHurricane risk diminishes dramatically with increasing distance from the shoreline. Most people minimize their personal risk by simply moving inland until the storm passes. Because hurricanes move fairly slowly and are tracked by satellite for days before landfall, people usually have plenty of time to evacuate before the storm strikes. However, for people who do not receive or understand the warning, or who do not have transportation to evacuate, the risk is considerably higher. Identifi cation of these increased-risk segments of the population would allow emergency planners to eff ectively focus their resources to assist those most in need.

In this exercise, you will identify where three specifi c increased-risk populations — the elderly, the poor, and non-English speakers — live in signifi cant numbers. Th e analysis is a multistep process involving both census data and the predicted storm-surge fl ooding maps. You will look at a case involving a Category 4 storm surge.

Investigation 4.3 Demographic factors

Demographic factors 89


Establish a baseline populationWhen assessing risk to segments of a population, it is important to fi rst understand the characteristics of the general population as a whole. In this case, you want to know the total population of the area. Th is provides an important yardstick, or baseline to which you can compare other measurements.

Launch ArcView, locate and open the cyclones.apr fi le, and open the NYC Topography and Demographics view.

Turn on the NYC Census Data theme.

Activate the NYC Census Data theme.

Th e gray areas in this theme are called census-block groups. Th e U.S. Census Bureau gathers and reports statistics for various-sized groups of people. Th e smallest of these are census blocks, areas containing about 70 people. Neighboring census blocks with similar characteristics are combined into census-block groups of approximately 500 households each.

Click the Statistics button .

In the Statistics window, calculate statistics for all features of the NYC Census Data theme, using the 1999 Population fi eld.

Select the Basic output option and click OK.

Th e total population for all of the census-block groups in the map area is given as the Total in the Statistics window. (Th e view does not show all of New York City. Th e total population of the city is much larger.)

1. What is the baseline (Total) population for New York City based on the NYC Census Data theme?

Close the Statistics window.

To turn a theme on or off , click its checkbox in the Table of Contents.

To activate a theme, click on its name in the Table of Contents.

90 Demographic factors


Identify groups in fl ooding areasAft er fi nding the baseline population, your next task is to identify the groups that would be fl ooded by a Category 4 storm surge.

First, you must use a query to highlight the Category 4 storm-surge area.


To display only the areas fl ooded by a Category 4 storm surge, query the NYC Storm Surge theme for ([Category] = “Category 4”) as shown in steps 1 – 6:

If you have diffi culty entering the query statement correctly, refer to the QuickLoad Query described at left .

Close the Query Builder window.

Next, you will perform a Select By Th eme operation to identify the census-block groups that are within the fl ooded areas.

Click the Select By Theme button .

In the Select By Th eme window, select features from the NYC Census Data theme that are completely contained by all the features of the NYC Storm Surge theme.

Click New, but do not close the Select By Theme window.

Th e census-block groups that are completely within the Category 4 storm-surge areas should now be highlighted.

QuickLoad Query • Click the QuickLoad Query

button, select the NYC Category 4 query, and click OK.

• Select the Display Only Found Features mode.

• Click New.

Read query statement here as you enter it.

2) Double-click Field

3) Single-click Operator

4) Double-click or type Value

5) Choose Display Mode 6) Click New

1) Select Theme



In the Select By Th eme window, click the Statistics button .

In the Statistics window, calculate statistics for the selected features of the NYC Census Data theme, using the 1999 Population fi eld.

Choose the Basic output option and click OK.

Th e total number of people in the aff ected areas is reported as the Total in the Statistics window.

2. How many people in New York City would be directly affected by a Category 4 storm surge?

3. What percentage of the baseline population (reported in question 1 on page 90) is this?

Close the Statistics and Select By Theme windows.

Identify areas with high increased-risk populationsTh e three increased-risk populations you want to identify are the elderly, the poor, and the non-English speakers. Although people in these populations are spread all over the city, you want to know where they are most heavily concentrated. Th at way, you will be able to focus most of your resources on these areas. Th e following is the critical concentration (percentage of the population) for each of these groups.

Table 1 — Critical concentrations of increased-risk populations in the New York City area

Increased-risk population Category Critical concentration

Over 65 years of age Elderly ≥ 19

Living below poverty level Poor ≥ 39

Non-English speakers Non-English speakers ≥ 23.5

You can assume that the general population will receive the evacuation warnings transmitted by television, radio, and the Internet. Your task is to target specifi c groups for door-to-door evacuation warnings. You will use a query to fi nd the subset of the fl ooded census blocks that have high increased-risk populations.


To highlight the areas in the Category 4 fl ood zone containing critical concentrations of one or more increased-risk populations, query the NYC Census Data theme for: (“ELDERLY” >= 19) OR (“POOR” >= 39) OR (“NOENGLISH” >= 23.5). Do not click New.

Click Highlight. Th en, click Subset. (Caution: Do not click New, or you will select all of the increased-risk areas in the city rather than just those in the fl ooded areas.)

Calculating the affected populationExample: Suppose non-English speakers make up 12.4 percent of a total aff ected population of 6,000,000. (Your numbers will be diff erent.) The aff ected population of non-English speakers is calculated as:

0.124 x 6,000,000 = 744,000



Click the Statistics button in the Query Builder window.

In the Statistics window, calculate statistics for the selected features of the NYC Census Data theme, using the 1999 Population fi eld.


Th e increased-risk population in the Category 4 fl ood areas is reported as the Total in the Statistics window.

4. What is the total number of people in the selected census-block groups that meet one or more of the increased-risk criteria?

5. What percentage of the total baseline population does this represent?

% of total population ([question ÷ question ] × ) = ______

6. What percentage of the population in the Category 4 storm-surge area is at increased risk?

% of increased-risk population in the Category 4 storm-surge area

([question ÷ question ] × ) = _________

Close the Statistics window.

To break down this total by category, you will fi nd the average percentage of each increased-risk group and multiply it by the total aff ected population.

Click the Statistics button in the Query Builder window.

In the Statistics window, calculate statistics for the selected features of the NYC Census Data theme, using the Elderly, Non-English Speakers, and Poor fi elds. Hold down the Shift key to select multiple fi elds.


Th e average of each of the three increased-risk categories is reported as the Mean in the Statistics window.

7. Record the average percentage of each of the 3 increased-risk categories in Table 2 on the following page. Round to the nearest whole number.

Calculating statisticsfor multiple fi eldsTo calculate statistics for more than one fi eld at a time:

• Click the fi rst fi eld to select it.

• Shift-click additional fi elds to select them.

• Click OK to calculate statistics.



Table 2 — Populations at increased risk from Category 4 storm surge

Increased-risk category

Average

%

Total aff ected

populationfrom question 4

Aff ected population in category

Average % × Total aff ected population

Elderly

Non-English Speakers

Poor

8. Enter the total aff ected population from question 4 in Table 2 and use it to calculate the aff ected population for each increased-risk category. Th e total aff ected population will be the same for all three categories.

On the map, the census-block groups containing high concentrations of increased-risk populations are highlighted.

9. Looking at the on-screen map, determine whether the concentrations of increased-risk groups are distributed evenly or clustered. What do you think accounts for the distribution you observe?

10. How might the distribution of increased-risk groups help or hinder eff orts to warn the citizens of the approaching hurricane?

11. Based on what you have learned in this investigation, how would you characterize the impact of a hurricane on New York City. Would it be minor, major, or catastrophic? Explain your answer.

Close the Statistics and Query Builder windows.

Quit ArcView and do not save changes.



Investigating storm surge and population demographics of New York City is just one of many possible scenarios worth exploring when studying the potential eff ects of a major hurricane on New York City. Natural disasters aff ect people, and the societies they are part of, in many diff erent ways. Th e previous example looked at the potential direct impact of hurricane fl oodwaters on increased-risk populations in New York City. Th e people living in the Category 4 storm-surge areas would be physically in danger of drowning or being struck by fl oating debris. What are some of the other hazards New Yorkers face?

Other hazards from hurricanes

Wind damageAnother example of a hurricane’s direct impact is severe wind damage to mobile-home parks or areas where housing is more than 50 years old. Th ese structures can be more susceptible to severe wind damage (i.e., collapse or disintegration) that would directly endanger their inhabitants. An emergency planner would certainly want to know where such areas were located, who lived there, and how they might warn or evacuate the residents before the disaster strikes.

Indirect effectsIn addition to direct eff ects from natural disasters, there are indirect eff ects, in which the natural disaster damages or destroys some part of the infrastructure that supports modern society. Most people take clean water, electricity, and food for granted, assuming that it will always be easily available. Although few people are killed or injured by hurricanes, many can be inconvenienced or become ill if they do not have safe drinking water, electricity, or food for an extended period of time.

Extended investigationsTh e following pages describe other investigations that you can carry out using the data included with this project. Each investigation describes the themes available for examining diff erent potential impacts of a major hurricane on New York City.

Working in teams, read through the descriptions of the investigations and choose one to work on as a group. Plan and carry out the investigation and be prepared to share your fi ndings with the class. Your instructor may provide you with additional research and presentation guidelines.

Assessing infrastructure

Be creative!Now that you know how to use GIS, this is your opportunity to be creative. See what else you can discover by experimenting and playing with the data. Have fun, but be sure to clean up New York City by turning off the storm surge when you are done.

Investigation 4.4

Assessing infrastructure 95


In planning for disasters, it is important for emergency planners to determine the capacity of a city or town to take care of people injured or displaced from their homes. Th e NYC Shelter and Hospital Assessment view allows you to use ArcView to look at the number of hospital beds and shelters that might be lost due to hurricane-related fl ooding and to draw conclusions about New York City’s ability to care for people during a natural disaster.

Investigation questions • How many hospital beds might be lost due to fl ooding?

• How many shelters (schools) would be fl ooded and not available as temporary housing?

• How many hospital beds and shelters are outside the fl ood areas?

• Where could emergency planners send people to shelters or hospitals outside the fl ood areas?

Themes available(Use the NYC Shelter and Hospital Assessment view.)

• NYC Hospitals — New York City hospital locations.

• NYC Schools — New York City public schools (could be used as storm shelters).

Extended Investigation 1 Shelters and hospitals

96 Assessing infrastructure


Manhattan, the heart of New York City, has some of the tallest buildings in the world. Many of these skyscrapers are glass towers that rise 70 – 100 stories above the city streets. At these altitudes, the wind gusts could be even stronger than at ground level, meaning that Category 4 hurricane winds could be well over 130 mph (210 km/hr).

Exactly how well a skyscraper would stand up to such winds is not known, but chances are good that windows would shatter and glass would be a major component of the fl ying debris.

Th is investigation examines the risk from falling glass debris, by defi ning 100-m buff er zones surrounding the tall buildings. Th e number of people at risk from fl ying debris can then be determined by using the census data with the skyscraper buff ers in a Select By Location operation. Th is number is low because the census reports only where people live, not where they work. Some of these large buildings can hold tens of thousands of employees.

Investigation topics • Identify the census-block groups that intersect the Skyscraper

Hazard Zones. Find the population density for those census-block groups, determine the mean population density, and apply that population density to the area of the New York City Skyscraper Hazard Zones to estimate the aff ected population.

Themes available(Use the NYC Skyscraper Assessment view.)

• Skyscrapers — Building outlines of the 30 tallest buildings in New York City.

• Skyscraper Hazard Zones — 100-m buff er zones surrounding the building perimeters that could be hazardous due to windows blowing out of the tallest buildings.

• NYC Census Data — Th e U.S. Census Bureau gathers and reports statistics for various-sized groups of people. Th e smallest of these are census blocks, areas containing about 70 people. Neighboring census blocks with similar characteristics are combined into census-block groups of around 500 households each.

Extended Investigation 2 Wind hazards



A serious hazard in any fl ood event is the possibility of water pollution as fl oodwaters inundate landfi lls, sewage treatment facilities, and industrial sites; and pick up chemical or biological contaminants. Th is investigation examines the locations of EPA Superfund sites in relation to the predicted hurricane storm surge, and uses GIS to identify areas or populations at risk from contaminated fl oodwaters.

Investigation topics • Identify Superfund sites that would be inundated by a Category 4

storm surge. Do a Select By Location operation to create a buff er around inundated Superfund sites, and determine the aff ected population.

• Identify hazards contained in the sites, and try to determine their impact on water and air quality.

Themes available(Use the NYC Superfund Site Hazard Assessment view.)

• Superfund Sites — CERCLIS Sites from EPA Region 2 GIS repository.

Extended Investigation 3 Superfund sites

Superfund sites — places that have been identifi ed as the worst hazardous-waste sites in the nation. The Superfund Program is run by the U.S. Environmental Protection Agency (EPA), in cooperation with local governments. Established by Congress in 1980, its mission includes locating, investigating, and cleaning up these sites.

For more information, visit the Superfund Web site at:

www.epa.gov/superfund



Roads, railways, and airports are the circulation system of cities, allowing people and goods to fl ow freely. People get to work and school, raw materials get to factories, food gets to supermarkets and restaurants. Disable part of the transportation network, and society grinds to a halt.

In this investigation, you can explore the impact of a major hurricane on New York City’s transportation infrastructure by looking at the railroad lines and roads that cross areas inundated by storm-surge fl oodwater. In addition, you can add data to the view to examine evacuation routes and accessibility to shelters and hospitals.

Investigation topics • Determine the length of roads and railroads fl ooded by a Category

4 storm surge.

• Identify evacuation routes that will likely remain open , and those that may be impassable due to storm fl ooding.

Themes available(Use the NYC Transportation Network Impact Assessment view.)

• Road Network — New York City interstate highways and major roads.

• Railroads — New York City railroads.

Extended Investigation 4 Transportation networks



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