> **Session No. 6**

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**Course Title: Coastal Hazards Management**

**Session Title: Coastal Hazards I**

**Author: Katherine Eschelbach, University of North Carolina at Chapel
Hill**

**Time: 50 minutes**

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**Objectives**

> 6.1 Understand the basic natural processes that contribute to the
> following coastal hazards: floods, hurricanes, coastal erosion, and
> tsunami

6.2 Discuss the extent of these hazards geographically and historically

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**Scope**

Sessions 6, 7, 8, and 9 help set the stage for the remainder of the
course. The information presented in this series of sessions will
contribute to the students' general understanding of the natural hazards
that are unique to the coastal zone, as well as some hazards that occur
in other areas as well. This background information is essential to a
broader understanding of the role of human beings in managing the
coastal zone, and in particular, the natural hazards that occur there,
as discussed throughout the remainder of the course.

Assuming many of the students do not have an extensive background in the
earth and physical sciences, the material is very basic. Most students
without a background in natural hazards may not be familiar with basic
physical science terms and the meteorological and geological processes
behind these natural hazards. The lecture, therefore, focuses on
conveying general principles and key features of the natural hazards
that are most common in the coastal zone.

Sessions 6 and 7 introduce students to the major natural hazards that
occur in the coastal zone. These sessions discuss the natural processes
that contribute to the major coastal hazards, where these hazards occur,
the frequency of their occurrence, and the impacts they may have on both
the human and the natural environments.

Session 6 (*Major Coastal Hazards, Part I*) covers the natural processes
that contribute to four selected major coastal hazards and their
frequency and distribution. These four hazards include: hurricanes,
coastal erosion, tsunami, and flooding.

Session 7 (*Major Coastal Hazards, Part II*) introduces the natural
processes involved in several other major coastal hazards (nor'easters,
rip current, and those associated with hurricanes: high wind, torrential
rain, and storm surge). Session 7 also addresses the impacts that the
coastal hazards in Session 6 may have on both humans and the
environment.

Later in the course we will present case studies of coastal hazards and
disasters in more detail.

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**Supplemental Considerations:**

The internet is a tremendous resource for background information on the
hazards discussed in both Sessions 6 and 7. Many of the federal
government websites cited in the lecture remarks below, such as the NOAA
and FEMA websites, are reliable and provide large amounts of information
for students and the public. The students should become familiar with
several of the websites as powerful resources of information.

An optional homework assignment, in addition to the student and
additional readings below, could be to assign the students these three
websites to become familiar with to summarize their favorite findings
for the class:

[www.noaa.gov](http://www.noaa.gov/)

[www.ncdc.noaa.gov](http://www.ncdc.noaa.gov/)

[www.fema.gov](http://www.fema.gov/)

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**Readings:**

*Instructor and Student Readings (for Sessions 6 & 7):*

Abbott, P.L. 1996. *Natural Disasters*. Dubuque, IA: Wm. C. Brown
Publishers, pp. 278-285: "Hurricanes;" pp. 293-320: "Floods;" pp.
321-38: "Coastal Erosion;" and pp. 339-348: "Tsunami."

Alexander, Grant. 1993. *Natural Disasters*. New York, NY: Chapman &
Hall, Inc., pp. 80-90: "Tsunami;" pp. 120-144: "Floods;" pp. 154-170:
"Hurricanes;" pp. 287-296: "Coastal

Erosion"

Bolt, B.A., W.L. Horn, G.A. Macdonald, and R.F. Scott. 1977. *Geological
Hazards:*

> *Earthquakes -- Tsunamis -- Volcanoes -- Avalanches -- Landslides --
> Floods, 2^nd^ ed.* New York, NY: Springer-Verlag, Chapter 3, pp.
> 132-147: "Hazards from Tsunamis;" Chapter 7, pp. 232-282: "Hazards
> from Floods."

Robinson, Andrew. 1993. *Earthshock: Hurricanes, Volcanoes, Earthquakes,
Tornadoes and*

> *Other Forces of Nature.* London: Thames and Hudson Ltd., pp. 117-136:
> "Hurricanes;" Chapter 6 pp. 153-186: "Floods, Dambursts and Tsunamis."

*Additional Background Reading (for sessions 6 & 7):*

Kauffman, W. and O.R. Pilkey, 1979. *Beaches are Moving*. Doubleday
Press.

Miller, E.Willard and Ruby M. Miller. 2000. *Natural Disasters:*
*Floods, A Reference Handbook.* Santa Barbara, CA: ABC-CLIO, Inc, pp.
1-2: "Origin of a Flood;" and pp. 23-46: "Types of Floods."

National Research Council. 1990. *Managing Coastal Erosion*. Washington,
D.C.: National Academy Press, pp. 20-43: "Coastal Erosion: Its Causes,
Effects, and Distribution."

Neighbor, R.J. 2003. Subsidence in the Greater Houston Area -- Past,
Present, and Future.

> CIGMAT-2003 Conference and Exhibition Proceedings:
> http://www2.egr.uh.edu/\~civeb1/CIGMAT/03_present/5.pdf

Simpson and Riehl. 1981. *The Hurricane and Its Impact*. Baton Rouge,
LA: Louisiana State

University Press, Part IV, pp.191 -- 270: "The Hurricane Impact."

The H. John Heinz III Center for Science, Economics and the Environment.
2000. *Evaluation*

> *of Erosion Hazards*. Prepared for the Federal Emergency Management
> Agency. Contract EMW-97-CO-035.
> [http://www.heinzcenter.org](http://www.heinzcenter.org/).

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**PowerPoint slides:**

**Part I: Session 6**

**PowerPoint 6.1** Lecture Outline

**PowerPoint 6.2** Introduction: What is a Coastal Hazard?

**Power Point 6.3** What is a Hurricane?

**PowerPoint 6.4** What is Coastal Erosion?

**PowerPoint 6.5** What is a Tsunami?

**PowerPoint 6. 6** What is a Flood?

**PowerPoint 6**.**7** Distribution of Hurricanes

**PowerPoint 6**.**8** Distribution of Coastal Erosion

**PowerPoint 6.9** Distribution of Tsunamis

**PowerPoint 6.10** Distribution of Floods

**Handouts:**

**Handout 6.1:** Examples of Hurricane Damage by Saffir-Simpson Category

### 

### Handout 6.2: List of Category 5 Atlantic Hurricanes (1886 - Present)

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**General Requirements:**

The Instructor should review some of the additional background reading
and prepare copies of handouts for students based on the accompanying
PowerPoint presentation.

As foundation classes, Sessions 6 through 9 will present baseline
information in a predominantly lecture format, supported by PowerPoint
slides. The slides are an essential part of this lecture series, as they
depict the natural hazards that will be discussed throughout the course.

Alternatively, the instructor may choose to cover the material in
sessions 6-9 very quickly during class with an abbreviated lecture. The
PowerPoint slides can then be used to prompt interactive discussion of
problems, issues and solutions -- drawing from theory and seeking to
develop and hone student analytical and critical thinking skills.

As a starting point, students could be asked about their experiences
with disasters and their awareness of the natural hazards that affect
the coast. The Instructor could also lead a discussion on the many
factors (political, social, economic, etc.) that must be considered in
managing these natural hazards. It will be interesting to see how the
students' perspectives of these issues may change over time as the
course develops a greater understanding of the complexities of hazard
management in the coastal zone.

The following slide will be used for the lecture outline:

> \[**PowerPoint 6.1** Lecture Outline\]

Note that the session breaks after the discussion of flooding
distribution as shown in PowerPoint 6.10. The discussion of Major
Coastal Hazards will resume in Session 7 with PowerPoint 7.1 depicting a
nor'easter hazard.

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**Objective 6.1: Understand the basic natural processes that contribute
to the following coastal hazards: floods, hurricanes, coastal erosion,
and tsunami**

**Requirements:**

The content should be presented as lecture, supported by PowerPoint
slides. **Handout 6.1** is provided within the Remarks for this
objective as well as an appendix at the end of this document.

The following slides will be used during this objective:

\[**PowerPoint 6.2** Introduction: What is a Coastal Hazard?\]

\[**Power Point 6.3** What is a Hurricane?\]

\[**PowerPoint 6.4** What is Coastal Erosion?\]

\[**PowerPoint 6.5** What is a Tsunami?\]

\[**PowerPoint 6. 6** What is a Flood?\]

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**Remarks:**

**II. Introduction: What is a coastal hazard?**

\[**PowerPoint 6.2** Introduction: What is a Coastal Hazard?\]

A.  A natural hazard is a natural process that occurs under certain
    extreme environmental

> conditions in the atmosphere, on the earth's surface, or under the
> ground.
>
> 1\. Natural hazards are often a source of astonishment and fear as
> well as respect
>
> for humans because of the awesome power that they contain.

B.  There are many different types of natural hazards, such as
    tornadoes, blizzards, drought,

> wildfire, volcanoes and earthquakes. ***Coastal hazards are those
> natural hazards that occur at the interface between the ocean and the
> shoreline.***

C.  The coastal hazards that are the most uniquely associated with the
    coast are **hurricanes,**

> **coastal erosion, and tsunami.** **Flooding** is another hazard --
> that although can occur in many places -- can also be very intense in
> coastal areas.

*This session will focus on the natural processes that contribute to
these four coastal hazards*. *Session 7 will make mention of several
others that occur along the coast in association with these hazards and
discuss the impacts of these hazards as well.*

**III. What is a hurricane?**

> \[**Power Point 6.3** What is a Hurricane?\]

A. Definition

1\. ***Hurricanes are cyclonic storms that originate in tropical ocean
waters*** pole ward of

> about 5^o^ latitude.[^1] Hurricanes are heat engines, fueled by the
> release of latent heat from the condensation of warm water.

2\. Their formation requires:

-   a low pressure disturbance,

-   sufficiently warm sea surface temperature,

-   rotational force from the spinning of the earth, and

-   the absence of wind shear in the lowest 50,000 feet of the
    atmosphere.

3\. Hurricanes can produce an array of hazardous weather conditions
including storm

> surges, high winds, torrential rain, and tornadoes.

**B. Description**

1.  Hurricanes have the greatest potential to inflict damage as they
    cross the coastline from the ocean, which is called **landfall**.
    Because hurricanes derive their strength from warm ocean waters,
    they are generally subject to deterioration once they make landfall.

2\. The forward momentum of a hurricane can vary from just a few miles
per hour to up to 40 mph. This forward motion combined with a
counterclockwise surface flow

make the right front quadrant of the hurricane the location of the most
potentially damaging winds.

3\. Hurricane intensity is measured using the Saffir-Simpson Scale,
ranging from 1

> (minimal) to 5 (catastrophic). The scale categorizes hurricane
> intensity linearly
>
> based upon maximum sustained winds, minimum barometric pressure and
> storm surge
>
> potential, which are combined to estimate of the potential flooding
> and damage to property given a hurricane\'s estimated intensity.

*Saffir-Simpson Hurricane Scale*[^2]

+-------------+--------+---------+------+---------------+------+-----+
| **Saf       |        |         |      |               |      |     |
| fir-Simpson |        |         |      |               |      |     |
| Scale**     |        |         |      |               |      |     |
+-------------+--------+---------+------+---------------+------+-----+
| ***Saf      | ***M   |         |      | ***Minimum*** | ***S |     |
| fir-Simpson | aximum |         |      |               | torm |     |
| Category*** | sustai |         |      | ***surface    | surg |     |
|             | ned*** |         |      | pressure***   | e*** |     |
|             |        |         |      |               |      |     |
|             | *      |         |      |               |      |     |
|             | **wind |         |      |               |      |     |
|             | sp     |         |      |               |      |     |
|             | eed*** |         |      |               |      |     |
+-------------+--------+---------+------+---------------+------+-----+
|             | ***    | *       | ***  | ***(          | **   | *** |
|             | mph*** | **meter | knot | millibars)*** | *fee | met |
|             |        | /sec*** | s*** |               | t*** | ers |
|             |        |         |      |               |      | *** |
+-------------+--------+---------+------+---------------+------+-----+
| 1           | 74-96  | 33-42   | 6    | Greater than  | 3-5  | 1   |
|             |        |         | 4-83 | 980           |      | .0- |
|             |        |         |      |               |      | 1.7 |
+-------------+--------+---------+------+---------------+------+-----+
| 2           | 97-111 | 43-49   | 8    | 979-965       | 6-8  | 1   |
|             |        |         | 4-96 |               |      | .8- |
|             |        |         |      |               |      | 2.6 |
+-------------+--------+---------+------+---------------+------+-----+
| 3           | 1      | 50-58   | 97   | 964-945       | 9-12 | 2   |
|             | 12-131 |         | -113 |               |      | .7- |
|             |        |         |      |               |      | 3.8 |
+-------------+--------+---------+------+---------------+------+-----+
| 4           | 1      | 59-69   | 114  | 944-920       | 1    | 3   |
|             | 32-155 |         | -135 |               | 3-18 | .9- |
|             |        |         |      |               |      | 5.6 |
+-------------+--------+---------+------+---------------+------+-----+
| 5           | 156+   | 70+     | 136+ | Less than 920 | 19+  | 5   |
|             |        |         |      |               |      | .7+ |
+-------------+--------+---------+------+---------------+------+-----+

4\. Hurricanes can be categorized as major hurricanes (the most
potentially dangerous)

> with a Saffir-Simpson classification of 3, 4 or 5.[^3] These intense
> hurricanes cause over 70% of the damage in the USA even though they
> account for only 20% of tropical cyclone landfalls.

*The following handout is made accessible for distribution:*

Handout 6.1: *Examples of Hurricane Damage by Saffir-Simpson Category*

+-----+--------+-----------------------------------------------+-------+
| **  |        |                                               |       |
| Hur |        |                                               |       |
| ric |        |                                               |       |
| ane |        |                                               |       |
| Ca  |        |                                               |       |
| teg |        |                                               |       |
| ory |        |                                               |       |
| Dam |        |                                               |       |
| age |        |                                               |       |
| E   |        |                                               |       |
| xam |        |                                               |       |
| ple |        |                                               |       |
| s** |        |                                               |       |
+-----+--------+-----------------------------------------------+-------+
| **  | ***Le  | ***Description***                             | ***   |
| *Ca | vel*** |                                               | Examp |
| teg |        |                                               | le*** |
| ory |        |                                               |       |
| *** |        |                                               |       |
+-----+--------+-----------------------------------------------+-------+
| 1   | M      | Damage primarily to shrubbery, trees,         | Hurr  |
|     | INIMAL | foliage, and unanchored homes. No real damage | icane |
|     |        | to other structures. Some damage to poorly    | Jerry |
|     |        | constructed signs. Low-lying coastal roads    |       |
|     |        | inundated, minor pier damage, some small      | \(1   |
|     |        | craft in exposed anchorage torn from          | 989\) |
|     |        | moorings.                                     |       |
+-----+--------+-----------------------------------------------+-------+
| 2   | MO     | Considerable damage to shrubbery and tree     | Hurr  |
|     | DERATE | foliage; some trees blown down. Major damage  | icane |
|     |        | to exposed mobile homes. Extensive damage to  | Bob   |
|     |        | poorly constructed signs. Some damage to      |       |
|     |        | roofing materials of buildings; some window   | \(1   |
|     |        | and door damage. No major damage to           | 991\) |
|     |        | buildings. Coast roads and low-lying escape   |       |
|     |        | routes inland cut by rising water 2 to 4      |       |
|     |        | hours before arrival of hurricane center.     |       |
|     |        | Considerable damage to piers. Marinas         |       |
|     |        | flooded. Small craft in unprotected           |       |
|     |        | anchorages torn from moorings. Evacuation of  |       |
|     |        | some shoreline residences and low-lying areas |       |
|     |        | required.                                     |       |
+-----+--------+-----------------------------------------------+-------+
| 3   | EXT    | Foliage torn from trees; large trees blown    | Hurr  |
|     | ENSIVE | down. Practically all poorly constructed      | icane |
|     |        | signs blown down. Some damage to roofing      | G     |
|     |        | materials of buildings; some wind and door    | loria |
|     |        | damage. Some structural damage to small       | (     |
|     |        | buildings. Mobile homes destroyed. Serious    | 1985) |
|     |        | flooding at coast and many smaller structures |       |
|     |        | near coast destroyed; larger structures near  |       |
|     |        | coast damaged by battering waves and floating |       |
|     |        | debris. Low-lying escape routes inland cut by |       |
|     |        | rising water 3 to 5 hours before hurricane    |       |
|     |        | center arrives. Flat terrain 5 feet of less   |       |
|     |        | above sea level flooded inland 8 miles or     |       |
|     |        | more. Evacuation of low- lying residences     |       |
|     |        | within several blocks of shoreline possibly   |       |
|     |        | required.                                     |       |
+-----+--------+-----------------------------------------------+-------+
| 4   | E      | Shrubs and trees blown down; all signs down.  | Hurr  |
|     | XTREME | Extensive damage to roofing materials,        | icane |
|     |        | windows and doors. Complete failures of roofs | A     |
|     |        | on many small residences. Complete            | ndrew |
|     |        | destruction of mobile homes. Flat terrain 10  | (     |
|     |        | feet of less above sea level flooded inland   | 1992) |
|     |        | as far as 6 miles. Major damage to lower      |       |
|     |        | floors of structures near shore due to        |       |
|     |        | flooding and battering by waves and floating  |       |
|     |        | debris. Low-lying escape routes inland cut by |       |
|     |        | rising water 3 to 5 hours before hurricane    |       |
|     |        | center arrives. Major erosion of beaches.     |       |
|     |        | Massive evacuation of all residences within   |       |
|     |        | 500 yards of shore possibly required, and of  |       |
|     |        | single- story residences within 2 miles of    |       |
|     |        | shore.                                        |       |
+-----+--------+-----------------------------------------------+-------+
| 5   | CATAST | Shrubs and trees blown down; considerable     | Hurr  |
|     | ROPHIC | damage to roofs of buildings; all signs down. | icane |
|     |        | Very severe and extensive damage to windows   | Ca    |
|     |        | and doors. Complete failure of roofs on many  | mille |
|     |        | residences and industrial buildings.          | (     |
|     |        | Extensive shattering of glass in windows and  | 1969) |
|     |        | doors. Some complete building failures. Small |       |
|     |        | buildings overturned or blown away. Complete  |       |
|     |        | destruction of mobile homes. Major damage to  |       |
|     |        | lower floors of all structures less than 15   |       |
|     |        | feet above sea level within 500 yards of      |       |
|     |        | shore. Low-lying escape routes inland cut by  |       |
|     |        | rising water 3 to 5 hours before hurricane    |       |
|     |        | center arrives. Massive evacuation of         |       |
|     |        | residential areas on low ground within 5 to   |       |
|     |        | 10 miles of shore possibly required.          |       |
+-----+--------+-----------------------------------------------+-------+

*Note to Instructor: Pause to encourage questions and discussion with
students about hurricanes.*

**IV. What is coastal erosion?**

> \[**PowerPoint 6.4** What is Coastal Erosion?\]

# **A. Definition**

1.  ***Coastal erosion is the wearing away of the land surface by
    detachment and***

> ***movement of soil and rock fragments, during a flood or storm or
> over a period of years, through the action of wind, water, or other
> geologic processes.***

-   Wind, waves, and long shore currents are the driving forces behind
    coastal erosion. This removal and deposition of sand permanently
    changes beach shape and structure.

-   Sand may be transported to land- side dunes, deep ocean trenches,
    other beaches, and deep ocean bottoms.

-   Additional factors involved in coastal erosion include human
    activity, sea-level rise, seasonal fluctuations, and climate change.

# **B. Description** 

1.  The beach system is one that is considered to be in dynamic
    equilibrium. This means that sand is moved from one location to
    another but it does not leave the system.

    -   For example, winter storms may remove significant amounts of
        sand, creating steep, narrow beaches.

    -   In the summer, gentle waves return the sand, widening beaches
        and creating gentle slopes.

    -   Sand movement will not be consistent year after year in the same
        location, however, because there are so many factors involved in
        coastal erosion.

2.  Episodic erosion is erosion induced by a single storm event.

-   Episodic erosion considers the vertical component of two factors:
    general beach profile lowering and localized conical scour around
    foundation supports.

-   Episodic erosion is relevant to foundation embedment depth and
    potential undermining.

3.  The term Erosion Hazard Area (EHA) is defined as an anticipated area
    being lost to shoreline retreat over a given period of time.

-   The projected inland extent of the area is measured in years times
    the average annual long-term recession rate.

*Note to Instructor: Pause to encourage questions and discussion with
students about coastal erosion.*

**V. What is a tsunami?**

> \[**PowerPoint 6.5** What is a Tsunami?\]

# 

# **A. Definition**

1.  ***The phenomenon we call a tsunami (soo-NAH-mee) is a series of
    waves of***

***extremely long wave length and long period generated in a body of
water by an***

***impulsive disturbance that displaces the water.***

2\. Tsunamis are primarily associated with earthquakes in oceanic and
coastal regions.

Landslides, volcanic eruptions, nuclear explosions, and impacts of
objects from outer

space (such as meteorites, asteroids, and comets) can also generate
tsunamis.

**B. Description**

1.  As the tsunami crosses the deep ocean, its length from crest to
    crest may be a hundred miles or more, yet its height from crest to
    trough will only be a few feet or less.

2.  They can not be felt aboard ships nor can they be seen from the air
    in the open ocean.

3.  In the deepest oceans, the waves will reach speeds exceeding 600
    miles per hour (970 km/hr).

4.  When the tsunami enters the shoaling water of coastlines in its
    path, the velocity of its waves diminishes and the wave height
    increases.

-   It is in these shallow waters that a large tsunami can crest to
    heights exceeding 100 feet (30 m) and strike with devastating force
    (West Coast and Alaska Tsunami Warning Center, NOAA).

5.  Monitoring of tsunami conditions is managed by two warning centers
    in the Pacific Ocean.

-   One center is in Hawaii, called the Pacific Tsunami Warning Center,
    and the other is in Alaska, the Alaskan Tsunami Warning Center.

-   These centers attempt to monitor seismological and tidal stations
    throughout the Pacific Basin in order to distribute tsunami warning
    information as quickly as possible.

*Note to Instructor: Pause to encourage questions and discussion with
students about tsunamis.*

**IV. What is a flood?**

> \[**PowerPoint 6. 6** What is a Flood?\]

**A. Definition**

1\. ***Flooding is a localized hazard that is generally the result of
excessive precipitation.***

2\. Floods can be generally considered in two categories**: flash
floods**, the product of heavy

localized precipitation in a short time period over a given location;
and **general floods**,

caused by precipitation over a longer time period and over a given river
basin.

**B. Description**

1\. To be sure, flooding is the most common environmental hazard, due to
the widespread

> geographical distribution of river valleys and coastal areas, and the
> attraction of human settlements to these areas.

-   Most recent presidential declarations of major disasters have been
    associated with flash and general floods.

2.  **Flash floods** occur within a few minutes or hours of heavy
    amounts of rainfall, from a

dam or levee failure, or from a sudden release of water held by an ice
jam.

-   Flash floods can destroy buildings and bridges, uproot trees, and
    scour out new drainage channels.

-   Heavy rains that produce flash floods can also trigger mudslides.

-   Most flash flooding is caused by slow-moving thunderstorms, repeated
    thunderstorms in a local area, or by heavy rains from hurricanes and
    tropical storms.

-   Although flash flooding occurs often along mountain streams, it is
    also common in urban areas where much of the ground is covered by
    impervious surfaces.

    -   Roads and buildings generate greater amounts of runoff than
        typical forested land. Fixed drainage channels in urban areas
        may be unable to contain the runoff that is generated by
        relatively small but intense rainfall events.

3.  A combination of river basin physiography, local thunderstorm
    movement, past soil

moisture conditions and the degree of vegetative clearing determine the
severity of a

> flooding event.

4.  Abnormal weather patterns may also contribute to flooding of a local
    area. Large-scale climatic events, such as the El Nino-Southern
    Oscillation in the Pacific have been linked to increased storm
    activity and flooding in the United States

5.  Nationally, July is the month in which most flash flooding events
    occur, and nearly 90%

of flash floods occur during the April through September period
(Frazier, 1979).

6.  While flash floods occur within hours of a rain event, **general
    flooding** is a longer-term

> event, and may last for several days. The primary types of flooding
> are *riverine flooding, coastal flooding and urban flooding*.

-   Periodic flooding of lands adjacent to non-tidal rivers and streams
    is a natural and inevitable occurrence. When stream flow exceeds the
    capacity of the normal water course, some of the above-normal stream
    flow spills over onto adjacent lands within the floodplain.

    -   The recurrence interval of a flood is defined as the average
        time interval, in years, expected to take place between the
        occurrence of a flood of a particular magnitude and an equal or
        larger flood. Flood magnitude increases with increasing
        recurrence interval.

-   **Riverine flooding** is a function of precipitation levels and
    water runoff volumes within the watershed of the stream or river.

    -   **Coastal flooding** is typically a result of storm surge,
        wind-driven waves, and heavy rainfall. These conditions are
        produced by hurricanes during the summer and fall, and
        nor\'easters and other large coastal storms during the winter
        and spring.

        -   Storm surges may overrun barrier islands and push sea water
            up coastal rivers and inlets, blocking the downstream flow
            of inland runoff.

        -   Thousands of acres of crops and forest lands may be
            inundated by both saltwater and freshwater.

        -   Escape routes, particularly from barrier islands, may be cut
            off quickly, stranding residents in flooded areas and
            hampering rescue efforts.

```{=html}
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```
-   **Urban flooding** occurs where there has been development within
    stream floodplains.

    -   This is partly a result of the use of waterways for
        transportation purposes in earlier times. Sites adjacent to
        rivers and coastal inlets provided convenient places to ship and
        receive commodities.

    -   The price of this accessibility was increased flooding of the
        ensuing urban areas. Urbanization increases the magnitude and
        frequency of floods by increasing impermeable surfaces,
        increasing the speed of drainage collection, reducing the
        carrying capacity of the land and, occasionally, overwhelming
        sewer systems.

7.  The severity of a flooding event is determined by a number of local
    factors, including river basin physiography, precipitation patterns,
    recent soil moisture conditions and

vegetative state. An assessment of flooding potential requires spatial
information at the

sub-county level.

*Note to Instructor: Pause to encourage questions and discussion with
students about flooding.*

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Objective 6.2 Discuss the extent of these hazards geographically and
historically**

**Requirements:**

The content should be presented as lecture, supported by PowerPoint
slides. **Handout 6.2** is provided within the Remarks for this
objective as well as an appendix at the end of this document.

The following slides will be used during this objective:

\[**PowerPoint 6**.**7** Distribution of Hurricanes\]

\[**PowerPoint 6**.**8** Distribution of Coastal Erosion\]

\[**PowerPoint 6.9** Distribution of Tsunami\]

\[**PowerPoint 6.10** Distribution of Floods\]

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Remarks:**

**VI. Hurricane Distribution**

\[**PowerPoint 6**.**7** Distribution of Hurricanes\]

1\. Hurricanes have been distributed widely across the coasts of the US.
Their tracks are

> very erratic and unpredictable in the long term.

2.  Although tracking technology continues to increase, it is still
    difficult for forecasters to

know exactly where a hurricane will make landfall prior to a few hours
of it happening.

3.  Hurricanes take place in the Western Hemisphere, whereas typhoons
    and cyclones take

place in the Eastern Hemisphere.

> The NCDC website:
> ([*http://www.ncdc.noaa.gov/oa/satellite/satelliteseye/educational/cat5hur.html*](http://www.ncdc.noaa.gov/oa/satellite/satelliteseye/educational/cat5hur.html))
> has a list of all Category 5 hurricanes (which must have sustained
> winds of over 155 mph) that have occurred from 1886 through 1998. This
> table is shown below and can be made accessible for distribution.

### Handout 6.2: List of Category 5 Atlantic Hurricanes (1886 - Present)

[*http://www.ncdc.noaa.gov/oa/satellite/satelliteseye/educational/cat5hur.html*](http://www.ncdc.noaa.gov/oa/satellite/satelliteseye/educational/cat5hur.html)

  ------------ ------------ --------------- ------------- -------------------
  **Number**   **Storm      **Maximum       **Date        **Landfall as\
               Name**       Wind**          Attained\     Category 5**
                                            (UTC)**       

  1            Not Named    140 kt, 160 mph Sep 13, 1928  Puerto Rico

  2            Not Named    140 kt, 160 mph Sep 5, 1932   Bahamas

  3            Not Named    140 kt, 160 mph Sep 3, 1935   US/FL Keys

  4            Not Named    140 kt, 160 mph Sep 19, 1938  \-\--

  5            Not Named    140 kt, 160 mph Sep 16, 1947  Bahamas

  6            Dog          160 k, 185 mph  Sep 6, 1950   \-\--

  7            Easy         140 kt, 160 mph Sep 7, 1951   \-\--

  8            Janet        150 kt, 175 mph Sep 28, 1955  Mexico

  9            Cleo         140 kt, 160 mph Aug 16, 1958  \-\--

  10           Donna        140 kt, 160 mph Sep 4, 1960   \-\--

  11           Ethel        140 kt, 160 mph Sep 15, 1960  \-\--

  12           Carla        150 kt, 175 mph Sep 11, 1961  \-\--

  13           Hattie       140 kt, 160 mph Oct 30, 1961  \-\--

  14           Beulah       140 kt, 160 mph Sep 20, 1967  \-\--

  15           Camille      165 kt, 190 mph Aug 17, 1969  US/MS

  16           Edith        140 kt,160 mph  Sep 9, 1971   Nicaragua

  17           Anita        150 kt, 175 mph Sep 2, 1977   \-\--

  18           David        150 kt, 175 mph Aug 30, 1979  \-\--

  19           Allen        165 kt, 190 mph Aug 7, 1980   \-\--

  20           Gilbert      160 kt, 185 mph Sep 14, 1988  Mexico

  21           Hugo         140 kt, 160 mph Sep 15, 1989  \-\--

  22           Mitch        155 kt, 180 mph Oct 26, 1998  \-\--
  ------------ ------------ --------------- ------------- -------------------

### *The website also gives the following interesting facts about hurricanes:*

-   "Through 1998, only twenty-two Atlantic storms have reached this
    intensity, and only eight were of category 5 strength at time of
    landfall. Of these 22, only two made U.S. landfall: the 1935 Florida
    Keys hurricane and Hurricane Camille, which hit the Mississippi
    coastline in 1969.

-   Note that several infamous storms which struck the U.S. are listed
    in the table above, but no entry appears in the \"Landfall\" column.
    This is because the storms had weakened to below Category 5
    intensity at the time of U.S. landfall.

-   Hurricanes which had reached Category 5 intensity but had weakened
    by the time of U.S. landfall include: hurricanes of 1928, 1938 (New
    England Hurricane), and 1947, plus Donna (1960), Ethel (1960), Carla
    (1961), Beulah (1967), David (1979), Allen (1980), Hugo (1989), and
    Mitch (1998). Though it was an extremely strong Category 4 storm,
    even at landfall, Hurricane Andrew never achieved Category 5
    status.\*

> \*"At the 10-year after Hurricane Andrew Retrospective Conference put
> on at Florida International University three years ago, I heard
> several speakers claim that based on recent analysis of storm damage,
> that the storm had been reclassified as a category 5 -- needs to be
> looked into to see if this is true or not -- even if up in the air the
> controversy needs to be recognized." -- W. Blanchard, 8/9/04 personal
> communication

  ------------------------------ ----------------- -------- -------- ------
  Most Intense At U.S Landfall:  1935 Florida Keys 892 mb/  26.35    140 kt
                                                            in/      

  Highest Winds at U.S.          1969 Camille      909 mb/  26.84    165 kt
  Landfall:                                                 in/      

  Most Intense Atlantic          1988 Gilbert      888 mb/  26.22    160 kt
  Hurricane:                                                in/      

  Longest as Category Five:      1980 Allen        899 mb/  26.55    165 kt
                                                            in/      
  ------------------------------ ----------------- -------- -------- ------

-   Hurricane Allen reached Category 5 intensity three times along its
    path through the southern Caribbean and Gulf of Mexico: twice these
    periods were of 24-hours duration and the third lasted 18 hours.

-   1\) With the exception of Camille, no Category 5 hurricanes have
    ever existed north of 30 degrees N nor south of 14 degrees N.

-   2\) Four oceanic areas have experienced Category 5 intensity
    hurricanes twice: (26.5N, 77W), (18N, 86W),(24.5N, 96.5W) and
    (28-30N, 89W) (the path of Camille)!

-   3\) Areas which have never experienced a landfalling hurricane of
    Category 5 intensity include: the U.S. East Coast, Cuba, Jamaica,
    nor most of the Windward or Leeward Islands"

**VIII. Coastal Erosion Distribution**

\[**PowerPoint 6**.**8** Distribution of Coastal Erosion\]

1.  Coastal erosion is a highly localized event that could take place on
    one end of an island and not at the other.

    -   Thus, there are many examples of coastal erosion, but it is not
        the same as the other hazards discussed in this session because
        it takes place over time and never occurs just as one event,
        such as a hurricane.

    -   However, a hurricane event can drastically increase the amount
        of coastal erosion that takes place in a short period of time.

    -   The amount of sea level rise also can contribute to coastal
        erosion, but the normal occurrence of this hazard makes it more
        of a daily hazard that progresses slowly over time.

2.  The corresponding slide for coastal erosion distribution shows a
    large scale example of erosion predictions for the state of
    Louisiana.

    i.  The example used on slide 6.8 \-- depicting land loss in
        Louisiana -- is attributable as much, if not more, to the
        subsidence of land there - for a variety of anthropogenic
        related reasons \-- as it is to erosion.[^4]

        1.  Houston, Texas, and the surrounding areas, provides another
            example in the Gulf of Mexico that especially has
            experienced considerable subsidence: "Over-reliance on
            groundwater in the region has led to subsidence or the
            irreversible sinking of the ground surface caused by aquifer
            depletion. Water levels in the Chicot and Evangeline
            aquifers had dropped by as much as 400 feet by 1973, causing
            up to **nine feet of subsidence** in parts of Harris County.
            **Almost all of the county has subsided at least one foot**;
            *subsidence in coastal areas ranges from six feet in Texas
            City to nine feet in Baytown.* Subsidence rates in Galveston
            County and eastern Harris County have slowed dramatically
            over the last few years because of efforts to reduce
            reliance on ground-water."[^5]

-   The average erosion rate on the Atlantic coast is roughly 2 to 3
    feet per year, but the states bordering the Gulf of Mexico have the
    nation's highest average annual erosion rate at 6 feet per year
    ([www.heinzcenter.org](http://www.heinzcenter.org/)).

-   Erosion also can occur on the rocky cliffs of the Pacific coast and
    have a 1-foot per year average, although this does not represent the
    large events that happen less frequently that do result in large
    amounts of erosion at one time.

-   The Great Lakes annual erosion rate is highly variable, ranging from
    0 to more than 10 feet per year depending on a number of
    hydrologic/meteorologic factors like lake level and wave action.

**VI. Tsunami Distribution**

\[**PowerPoint 6.9** Distribution of Tsunami\]

1\. Tsunamis have historically occurred along the Pacific Coasts of the
United States,

> especially in Hawaii and Alaska, but result from earthquakes and
> landslides that occur not only within the US, but world wide.

-   The 1957 Aleutian earthquake had a dramatic effect on Hawaii as well
    as Alaska.

-   A tsunami that struck Hawaii in 1960 was the result of an earthquake
    in Chile, South America.

2\. Tsunamis are very rare along the Atlantic Coast of the United
States.

-   There is evidence that one tsunami occurred along these cracks
    16,000 to 18,000 years ago (Associated Press, 2000).

-   The tsunami referred to as the 1929 Grand Banks Canada event
    (precipitated by an earthquake with a Richter Scale magnitude of
    7.2) impacted upon the Maine shoreline.

-   However, the eastern seaboard is vulnerable to a large scale tsunami
    in the future due to its proximity to the Canary Island of La Palma
    in Africa[^6]. La Palma has the potential to have volcanic eruptions
    that would trigger a landslide capable of causing a large tsunami
    event for the entire US Atlantic seaboard.

-   High levels of gas hydrates along the continental shelf also could
    cause tsunamis.[^7]

**X. Flood Distribution**

\[**PowerPoint 6.10** Distribution of Floods\]

1.  Flood hazard varies by location and type of flooding.

-   Coastal areas are most at risk from flooding caused by hurricanes,
    tropical storms and nor\'easters.

-   Low-lying coastal areas in close proximity to the shore, sounds or
    estuaries are exposed to the threat of flooding from storm surge and
    wind-driven waves, as well as from intense rainfall.

-   Areas bordering rivers may also be affected by large discharges
    caused by heavy rainfall over upstream areas.

2.  Floodplains are divisible into areas expected to be inundated by
    spillovers from stream flow levels associated with specific
    flood-return frequencies.

-   A two-year return period event will generally inundate all the
    two-year zone of the floodplain, and a 100-year flood will inundate
    the 100-year zone of that floodplain.

3.  Floodplains may be divided into as many as six levels of flood
    class, corresponding to six different hazard zones (A through F).

-   Zone A represents the areas flooded by a 2-5 year flood;

-   Zone B, a 5-10 year flood;

-   Zone C, a 10-25 year flood;

-   Zone D, a 25-50 year flood;

-   Zone E, a 50-100 year flood; and

-   Zone F, a greater than 100 year flood.

-   The Army Corps of Engineers calls a 100-year flood an Intermediate
    Regional Flood,

-   while a Standard Project flood describes a major flood that could be
    expected to occur from a combination of severe meteorological and
    hydrologic conditions (Griggs, 1983).

-   Most dam and flood-related structures have been designed to meet
    100-year flood conditions.

*Note to Instructor: Pause to encourage questions and discussion with
students about hazard distribution.*

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[^1]: Simpson and Reihl (1981)

[^2]: Simpson and Reihl, 1981

[^3]: Landsea (1998)

[^4]: W. Blanchard, 8/9/04 personal communication

[^5]: [http://www.cechouston.org/resourceguide/drinkingwater.html]{.underline}

[^6]: [http://www.cdnn.info/article/tsunami/tsunami.html]{.underline}

[^7]: <http://www.ldeo.columbia.edu/edu/eesj/casestudies/EESJtsunami.html>

    \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

    **Appendix A: Handouts**

    ***Handout 6.1 and Handout 6.2: available for photocopy and
    distribution to students***

    Handout 6.1: *Examples of Hurricane Damage by Saffir-Simpson
    Category*

    **Hurricane Category Damage
    Examples*CategoryLevelDescriptionExample***1MINIMALDamage primarily
    to shrubbery, trees, foliage, and unanchored homes. No real damage
    to other structures. Some damage to poorly constructed signs.
    Low-lying coastal roads inundated, minor pier damage, some small
    craft in exposed anchorage torn from moorings.Hurricane Jerry

    (1989)2MODERATEConsiderable damage to shrubbery and tree foliage;
    some trees blown down. Major damage to exposed mobile homes.
    Extensive damage to poorly constructed signs. Some damage to roofing
    materials of buildings; some window and door damage. No major damage
    to buildings. Coast roads and low-lying escape routes inland cut by
    rising water 2 to 4 hours before arrival of hurricane center.
    Considerable damage to piers. Marinas flooded. Small craft in
    unprotected anchorages torn from moorings. Evacuation of some
    shoreline residences and low-lying areas required.Hurricane Bob

    ### (1991)3EXTENSIVEFoliage torn from trees; large trees blown down. Practically all poorly constructed signs blown down. Some damage to roofing materials of buildings; some wind and door damage. Some structural damage to small buildings. Mobile homes destroyed. Serious flooding at coast and many smaller structures near coast destroyed; larger structures near coast damaged by battering waves and floating debris. Low-lying escape routes inland cut by rising water 3 to 5 hours before hurricane center arrives. Flat terrain 5 feet of less above sea level flooded inland 8 miles or more. Evacuation of low- lying residences within several blocks of shoreline possibly required.Hurricane Gloria (1985)4EXTREMEShrubs and trees blown down; all signs down. Extensive damage to roofing materials, windows and doors. Complete failures of roofs on many small residences. Complete destruction of mobile homes. Flat terrain 10 feet of less above sea level flooded inland as far as 6 miles. Major damage to lower floors of structures near shore due to flooding and battering by waves and floating debris. Low-lying escape routes inland cut by rising water 3 to 5 hours before hurricane center arrives. Major erosion of beaches. Massive evacuation of all residences within 500 yards of shore possibly required, and of single- story residences within 2 miles of shore.Hurricane Andrew (1992)5CATASTROPHICShrubs and trees blown down; considerable damage to roofs of buildings; all signs down. Very severe and extensive damage to windows and doors. Complete failure of roofs on many residences and industrial buildings. Extensive shattering of glass in windows and doors. Some complete building failures. Small buildings overturned or blown away. Complete destruction of mobile homes. Major damage to lower floors of all structures less than 15 feet above sea level within 500 yards of shore. Low-lying escape routes inland cut by rising water 3 to 5 hours before hurricane center arrives. Massive evacuation of residential areas on low ground within 5 to 10 miles of shore possibly required.Hurricane Camille (1969)Handout 6.2: List of Category 5 Atlantic Hurricanes (1886 - Present)

    ### [*http://www.ncdc.noaa.gov/oa/satellite/satelliteseye/educational/cat5hur.html*](http://www.ncdc.noaa.gov/oa/satellite/satelliteseye/educational/cat5hur.html)

    **Number Storm Name Maximum Wind Date Attained\
    (UTC) Landfall as\
    Category 5** 1 Not Named 140 kt, 160 mph Sep 13, 1928 Puerto Rico 2
    Not Named 140 kt, 160 mph Sep 5, 1932 Bahamas 3 Not Named 140 kt,
    160 mph Sep 3, 1935 US/FL Keys 4 Not Named 140 kt, 160 mph Sep 19,
    1938 \-\-- 5 Not Named 140 kt, 160 mph Sep 16, 1947 Bahamas 6 Dog
    160 kt, 185 mph Sep 6, 1950 \-\-- 7 Easy 140 kt, 160 mph Sep 7, 1951
    \-\-- 8 Janet 150 kt, 175 mph Sep 28, 1955 Mexico 9 Cleo 140 kt, 160
    mph Aug 16, 1958 \-\-- 10 Donna 140 kt, 160 mph Sep 4, 1960 \-\-- 11
    Ethel 140 kt, 160 mph Sep 15, 1960 \-\-- 12 Carla 150 kt, 175 mph
    Sep 11, 1961 \-\-- 13 Hattie 140 kt, 160 mph Oct 30, 1961 \-\-- 14
    Beulah 140 kt, 160 mph Sep 20, 1967 \-\-- 15 Camille 165 kt, 190 mph
    Aug 17, 1969 US/MS 16 Edith 140 kt, 160 mph Sep 9, 1971 Nicaragua 17
    Anita 150 kt, 175 mph Sep 2, 1977 \-\-- 18 David 150 kt, 75 mph Aug
    30, 1979 \-\-- 19 Allen 165 kt, 190 mph Aug 7, 1980 \-\-- 20 Gilbert
    160 kt, 185 mph Sep 14, 1988 Mexico 21 Hugo 140 kt, 160 mph Sep 15,
    1989 \-\-- 22 Mitch 155 kt, 180 mph Oct 26, 1998 \-\-- "At the
    10-year after hurricane Andrew Retrospective Conference put on at
    Florida International University three years ago, I heard several
    speakers claim that based on recent analysis of storm damage, that
    the storm had been reclassified as a category 5 -- needs to be
    looked into to see if this is true or not -- even if up in the air
    the controversy needs to be recognized." -- W. Blanchard, 8/9/04
    personal communication

    **Appendix B: Course Developer References**

    Blanchard, Wayne. Higher Education Project Manager, Emergency
    Management Institute,

    > Federal Emergency Management Agency (FEMA). August 9, 2004 email
    > personal communication*.*

    Simpson and Reihl (1981)

    Landsea (1998)

    [http://www.cdnn.info/article/tsunami/tsunami.html]{.underline}

    <http://www.ldeo.columbia.edu/edu/eesj/casestudies/EESJtsunami.html>

    [www.heinzcenter.org](http://www.heinzcenter.org/)

    [*http://www.ncdc.noaa.gov/oa/satellite/satelliteseye/educational/cat5hur.html*](http://www.ncdc.noaa.gov/oa/satellite/satelliteseye/educational/cat5hur.html)

    **Appendix C: Power Point Graphics Citations**

    **Part I: Session 6**

    **PowerPoint 6.1** Lecture Outline

    (Courtesy: http://www.nasa.gov/)

    **PowerPoint 6.2** Introduction: What is a Coastal Hazard?

    (Courtesy: [www.missouri.edu/\~geoscmbu/
    ocean2003.html](http://www.missouri.edu/~geoscmbu/ocean2003.html) )

    (Courtesy: www.hyperreal.org/\~mike/livejournal/)

    (Courtesy: http://www.library.yale.edu/MapColl/hyannis.htm)

    (Courtesy: www.electrofin.com)

    **Power Point 6.3** What is a Hurricane?

    (Courtesy: http://www.mthurricane.com/hurricanes.htm)

    (Courtesy: NOAA Photo Library)

    (Courtesy: http://hpccsun.unl.edu/nebraska/Gtrack.html)

    (Courtesy:http://www.weatherstock.com/hurricanecat-science2.html)

    **PowerPoint 6.4** What is Coastal Erosion?

    (Black-and-white photographs courtesy of Pacific Studios, Newport,
    Oregon.\
    Color photographs taken by Parke D. Snavely, Jr. of the USGS.)

    **PowerPoint 6.5** What is a Tsunami?

    (Courtesy: National Weather Service)

    (Courtesy: users.belgacom.net)

    (Courtesy: FEMA)

    **PowerPoint 6. 6** What is a Flood?

    (Courtesy: www.utahweather.org)

    (Courtesy: http://www.sci.muni.cz/botany/gallery/lf109.jpg)

    **PowerPoint 6**.**7** Distribution of Hurricanes

    (Courtesy: NOAA)

    (Courtesy:
    [ww2010.atmos.uiuc.edu](http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/names.rxml)
    )

    **PowerPoint 6**.**8** Distribution of Coastal Erosion

    (Courtesy: The Heinz Center Evaluation of Erosion Hazards)

    (Courtesy: US Army Corps of Engineers)

    **PowerPoint 6.9** Distribution of Tsunamis

    (Courtesy:
    http://www.geophys.washington.edu/tsunami/general/historic/historic.html)

    **PowerPoint 6.10** Distribution of Floods

    (Courtesy: [www.nhoem.state.nh.us](http://www.nhoem.state.nh.us/) )