**Course Title: Floodplain Management**

**Module:** Risk to Human Settlements

**Session 19:** Mitigating Flood Losses

**Authors:** Larry A. Larson, PE, CFM

Rod E. Emmer, Ph.D.

**Time: 75 minutes**

**Objectives (PP1 and PP2; Title and Objectives)**

At the end of this session, students should be able to:

19.1 Explain the beneficial and detrimental attributes of structural
mitigation practices

19.2 Explain the beneficial and detrimental attributes of nonstructural
mitigation practices

19.3 Complete the Module examination.

**Scope**

Students should already be able to explain floods as hazards and how
communities and individuals are at risk. Session 19 builds on the
concept of floodplain management presented in Session 18.

The overall goal of Session 19 is to explain the importance of
mitigation in preventing flood damages, protecting existing and future
development, reducing injuries, and avoiding loss of life

In this session, the instructor introduces and discusses the range of
structural and nonstructural mitigation practices. Application of these
actions to mitigate flood impacts demonstrates the effectiveness and
limitations of each option. In consideration of the effectiveness and
limitations each option, students will be prepared to apply the range of
structural and nonstructural mitigation practices to mitigate flood
impacts in a riverine landscape.

Exercises give the students an opportunity to apply what they learned so
as professional floodplain managers they will be able to make decisions
that are more informed. These exercises are opportunities for engaging
the class and are implemented at the instructor\'s discretion.

**Readings**

*Required Student Readings*

Godschalk, D.R., T. Beatley, P. Berke, D.J. Brower, E.J. Kaiser, C.C.
Bohl, R.M. Goebel. 1999. \"Chapter 2. Evolving Mitigation Policy
Directions.\" *Natural Hazard Mitigation. Recasting Disaster Policy and
Planning.* Washington, D.C.: Island Press. Pp. 27-87.

Tennessee Valley Authority. 1983. *FLOODPLAIN MANAGEMENT: THE TVA
EXPERIENCE.* TVA/ONRED/AWR 86/55. Division of Economic and Community
Development. Knoxville, TN. December. 80 p.

United States Water Resources Council. 1981. *FLOODPLAIN MANAGEMENT
HANDBOOK.* Prepared by Flood Loss Reduction Associates. Washington,
D.C.: US Government Printing Office. September. 69 p. plus appendix.

*Instructor Readings*

Association of State Floodplain Managers. 2003. *No Adverse Impact.* *A
Toolkit for Common Sense Floodplain Management.* April 23 Draft.
Madison, WI. 79 p.

Eadie, C., R.E. Emmer, A.M. Esnard, S. Michaels, J. Monday, C.
Philipsborn, B. Phillips, d. Salvesen. 2001. *Holistic Disaster
Recovery. Ideas for Building Local Sustainability after a Natural
Disaster.* Natural Hazards Research and Applications Information Center,
University of Colorado, Boulder, CO. www.colorado.edu/hazards/

Federal Emergency Management Agency.1997. *Report on Costs and Benefits
of Natural Hazard Mitigation.* FEMA-294/7/97.

Federal Emergency Management Agency. 2003. *Developing the Mitigation
Plan. Identifying Mitigation Actions and Implementation Strategies.
State and Local Mitigation Planning How-to Guide.* FEMA 386-3. April.

Godschalk, D.R., T. Beatley, P. Berke, D.J. Brower, E.J. Kaiser, C.C.
Bohl, R.M. Goebel. 1999. \"Chapter 1. Mitigating Natural Hazards: A
National Challenge.\" *Natural Hazard Mitigation. Recasting Disaster
Policy and Planning.* Washington, D.C.: Island Press. Pp. 3-25.

Mileti, D.S. 1999. \"5. Influences on the Adoption and Implementation of
Mitigation.\" *Disasters by Design. A Reassessment of Natural Hazards in
the United States.* Washington, D.C.: Joseph Henry Press. Pp. 135 - 154.

Mileti, D.S. 1999. \"6. Tools for Sustainable Hazards Mitigation*.\"
Disasters by Design. A Reassessment of Natural Hazards in the United
States.* Washington, D.C.: Joseph Henry Press. Pp.155 - 207.

**General Requirements**

The Instructor should prepare copies and distribute a handout of the new
terms (19H1) that will be added to each student\'s course Glossary begun
in Session 1.

When distributing the handouts the Instructor should remind students
that we must agree on the meaning of terms, so we can more effectively
communicate with other professionals, local decision-makers, and the
general public. By avoiding any misunderstandings when speaking about
mitigation, they will have done a service to their community by saving
them time and money. The students should develop a personal Glossary
that they continually update as they work through classes and, more
importantly, when they move into their professional career. Remind
students that they are serving as the interpreter (translator) of
technical concepts for local officials and decision-makers with little
if any training, experience, or background in floodplain management.

The instructor may elect to review selected terms discussed in Sessions
15 - 18. By refreshing the students\' memory at the beginning of Session
19, the instructor draws their attention to again thinking about floods
and floodplain management.

Note:

Session 18 discussed the history, elements, and methodologies that
makeup floodplain management. **(PP3, Mitigation Measures)** One of the
most important elements of floodplain management is mitigation---the
actions taken to eliminate or reduce to an acceptable level the
undesired consequences of floods. For the community and individual this
may mean preventing flood damages to existing land uses and future
development, reducing injuries, and avoiding loss of life. Mitigation
measures include a range of structural and nonstructural practices that
when implemented have positive (favorable) characteristics and negative
(adverse) characteristics that should be considered by decision-makers
when addressing flood damage reduction. Session 19 presents the forms of
structural and nonstructural practices (approaches), summarizes their
functions, and identifies the beneficial and detrimental attributes of
each. Ultimately, the overall intent of flood damage reduction through
mitigation measures is No Adverse Impact **(PP4, No Adverse Impact)** on
the property and rights of others while solving flood problems.

**Remarks:**

**Objective 19.1 Explain the beneficial and detrimental attributes of
structural mitigation practices** **(PP5, Structural Mitigation
Practices)**

I. What is Structural Mitigation?

A. Structural mitigation includes corrective measures (practices) or
approaches that modify the floods themselves through the construction of
selected engineering works.

1\. Think of structural measures as keeping floodwaters away from
developments, populated areas, and agricultural lands by decreasing
runoff, increasing channel capacity, or containing, diverting, or
storing excess waters.

B. We modify floods in several ways (U.S. Water Resources Council, 1981,
p. 30):

1\. Dams and reservoirs

2\. Levees and walls

3\. Channel alterations

4\. Diversions

5\. Land treatment

6\. Onsite detention

C. Each of these measures is normally intended to protect an area rather
than a particular property (parcel) or person. As such, these public
works projects require little disruption to homes, businesses, and life
styles for most floodplain occupants.

**Interactive Class Activity:**

Ask students to name specific examples in their area that are instances
of structural mitigation.

D. According to the U.S. Water Resources Council, (1981, p. 30) several
problems are associated with large public works construction projects:
**(PP6, Disadvantages)**

*1. Lengthy and complex planning and design.*

*2. Require heavy construction and high costs.*

*3. Potential for making flood damages outside the project more severe.*

*4. Potential for catastrophic losses if design levels are exceeded.*

*5. Potential for creating a false sense of security about the extent of
protection provided.*

*6. Need for careful and costly routine inspection, operation, and
maintenance.*

*7. Possible detrimental effects to the natural environment.*

E. The Association of State Floodplain Managers (2003, pp. 45-46) offers
a similar list of potential adverse impacts when floods are modified.
Construction projects:

*1. Disturb the land and disrupt natural water flows, often destroying
habitats.*

*2. Are built to a certain flood protection level that can be exceeded
by a larger flood, causing even more damage than might have occurred
without the structure.*

*3. Can create a false sense of security when people protected by a
structure believe that no flood could every reach them.*

*4. Require regular maintenance to ensure that they continue to provide
protection, something that is often neglected over the years. On
structural projects, operation and maintenance are usually a local
cost.*

*5. Are expensive, sometimes requiring capital bond issues and/or cost
sharing with local, regional, or state agencies.*

*6. Projects such as levees and floodwalls can divert flood flow onto
other properties and reduce the floodplain\'s storage capacity.*

*7. Can alter the timing of flood peaks, causing increased flooding on
other properties.*

**II. Beneficial and detrimental attributes of structural mitigation
practices**

A. Dams and reservoirs (**PP7, Dams and Reservoirs)**

1\. Functions

a\. Dams and reservoirs such as Grand Coulee in Washington State **(PP8,
Grand Coulee Dam)** capture and temporarily hold floodwaters upstream of
flood prone areas. After the flood threat has passed, water is released
at a rate that the flooplain can accommodate.

b\. As a stream impoundment with controllable outlets, they are most
frequently used on small and moderate sized watercourses (U.S. Water
Resources Council, 1981, p. 30).

2\. Beneficial Attributes

> a\. Dams can reduce flood elevations for a given stretch of river and
> across a defined area downstream of the structure.

b.  Reservoirs may be multipurpose, i.e., flood control, recreation,
    water supply, irrigation, and navigation.

c.  Reservoirs may create desirable ecosystems, such as wetlands on
    former uplands.

d.  Private property values along shorelines usually increase as a
    result of access to the reservoir.

e.  Economic development may result from construction of a multipurpose
    reservoir.

f.  Little or no disruption to land use activities, as the protected
    properties are for the most part downstream from the project.

3\. Detrimental Attributes

a\. Reservoirs will change ecosystems, for example, open water may
replace wetlands as the pool level rises. This may be undesirable.

> b\. Dams and reservoirs require acquisition of project lands for
> buffers, the structure, and the pool. This acreage is removed from
> development, owners may be dislocated or its historic value may be
> lost.
>
> c\. Dams are not cheap, especially in an urban setting.
>
> d\. Reservoirs can lose their flood storage capacity as a result of
> sedimentation and filling.
>
> e\. Dams like other structural projects instill a false sense of
> security. Development encroaches onto supposedly protected
> floodplains.
>
> f\. Dam failure will cause catastrophic loss of life and destruction
> of property. On June 5, 1976, the Teton Dam in southeast Idaho failed.
> When the earthen dam breached, 250,000 acre-feet of water rushed down
> the valley and onto the flat farmlands. Rexburg, ID and other small
> farming communities were flooded, resulting in 11 deaths and over
> \$400 million damages.

g.  A new and growing concern is that large structural projects are
    potential targets for terrorist attacks. This is particularly true
    of large dams and reservoirs, large levees, and floodwalls. This not
    only presents a safety hazard, but also can add significantly to
    annual Operations and Maintenance costs.

B. Levees and walls **(PP9, Levees and Walls)**

1\. Functions

a\. Levees along the Mississippi River **(PP10)** and walls such as in
the French Quarter of New Orleans **(PP11)** reduce the size of the
floodplain or floodway by confining flow.

b\. Using sheet piles or concrete walls allows for narrower
rights-of-way. (Explanation note: Sheet pile is 3/8 in. X 18 in. X 40
+/- ft lengths of sculptured steel or plastic designed to interlock and
prevent seepage.)

2\. Beneficial Attributes

> a\. In contrast to levees, a floodwall requires less right-of-way in
> developed areas and reduced seepage under or through the structure.

b\. Depending on the location levees may be less expensive to build than
floodwalls. However, consideration must be given to the cost of
rights-of-way.

> c\. Levees and floodwalls can be located and built to protect specific
> areas and groups of structures.

d.  Levees can be designed as multipurpose facilities allowing
    construction of roads, trails, or bike or jogging paths on their
    crest or within their right-of-way. Such multiple uses are amenities
    for the community.

3\. Detrimental Attributes

> a\. Levees are mostly used along larger rivers where space is
> available for rights-of-way. Floodwalls in the same location would be
> more expensive.
>
> b\. Earthen levees usually require wide rights-of-way because their
> base must be broad and in proportion to their height.
>
> c\. Similar to dams and reservoirs, levees and walls encourage a false
> sense of security in those who live within the system. When a failure
> such as overtopping occurs, the resultant damages can be catastrophic.
>
> d\. Unless they are made part of a watershed or comprehensive
> community plan, with mitigation, flood frequency, depths, and erosion
> are simply shifted to other areas of the floodplain or along the
> channel.

e\. Secondary consequences of these structures include:

1)  Loss of access to adjacent lands, essentially isolating the
    community from the watercourse.

2)  Modification of habitats due to fill, excavation, ponding, or
    drainage. (removal of groundwater flow paths)

3)  A need for pump systems to remove internal runoff.

4)  An obstruction of views.

5)  Limiting access to the natural functions of the river.

C. Channel alterations **(PP11, Channel Alternatives)**

1\. Function

a\. Channel alterations such as straightening, deepening, widening,
removing debris **(PP12, Picture of Bayou Fountain ),** paving, raising
or enlarging the bridges and culverts, and removing dams can increase
the carrying capacity of watercourse (U.S. Water Resources Council,
1981).

b\. Channel alterations also lower flood elevations.

2\. Beneficial Attributes

a\. Channel alterations reduce the extent, and duration of floods.

b\. Channel alterations can protect specific sites of localized flooding
in developed areas.

c.  Channel alterations may be designed as part of a multipurpose
    project that not only serves for flood reduction but also navigation
    and recreation.

d.  Removing dams can restore natural ecosystems, including fish
    migration and canoeing.

3\. Detrimental Attributes

> a\. Changing the natural regime and storage capacity of the
> watercourse will accelerate runoff that may cause added flooding
> downstream.
>
> b\. Channel deepening of larger streams must include a dredge
> maintenance component in order to maintain the capacity of the
> channel, an expensive action for the local sponsors.
>
> c\. Modified channels will try to return to their original meandering
> configuration, requiring ongoing maintenance to keep the channel in
> the project location.

d\. Channel alteration results in habitat modification such as loss of
wetlands, covering of shellfish beds, and removal of submerged aquatic
vegetation, loss of spawning and rearing habitat, forced relocation of
fish and shellfish, and changed migration routes.

D. Diversions **(PP13, Diversion)**

1\. Functions

a\. Diversions sometimes called spillways **(PP14, Bonnet Carré)**
capture a predetermined flow from the watercourse such as 50% of the
100-year flood discharge and route the water through an artificial
channel to receiving bodies (lakes, estuaries, larger rivers, adjourning
watersheds). (U.S. Water Resources Council, 1981). In the example of the
Bonnet Carré Spillway, it can divert 250,000 cfs from the Mississippi
River into Lake Pontchartrain, thereby reducing the flood stage at New
Orleans, LA.

b\. The placement of diversions is dependant on the landscape, the
topography (the flatter the better), geology, and similar physical and
biological factors and the ability of a receiving body to handle the
additional flow.

2\. Beneficial Attributes

a\. Diversion can reduce flood levels affecting developed areas that are
immediately downstream from the project.

> b\. Diversion structures may use parcels of land that are less
> expensive than the highly urbanized area that might otherwise be
> protected with a levee.

3\. Detrimental Attributes

> a\. Like dams, levees, and floodwalls, diversions give that false
> sense of security in the \"protected area\".
>
> b\. Although the diversion structure may be small, the right-of-way
> for the channel (canal) may require significant land to allow for
> maintenance roads, account for bank erosion and stabilization, and
> safety fencing.
>
> c\. State laws may prohibit interbasin transfer of water.

E. Land treatment **(PP15)**

1\. Functions

a\. Land treatments are improvement practices to reduce runoff
throughout a watershed (uplands as well as floodplains) **(PP16, Land
Treatment).** This requires modifying the landscape (physical,
biological, and socioeconomic systems) to reduce flooding downstream.

b\. Land treatment practices include, but are not limited to: protecting
forests and the under story, planting vegetative cover, terracing, slope
stabilization, grass waterways, contour plowing, and strip farming (U.S.
Water Resources Council, 1981).

2\. Beneficial Attributes

> a\. Land treatments are most commonly used on agricultural lands to
> slow runoff, improve infiltration of precipitation into the soil, and
> help maintain or recharge aquifers.
>
> b\. Land treatment reduces erosion and subsequent sediment that fills
> streams and reservoirs.
>
> c\. Selected land treatments (no till or minimum tillage) result in
> little or no additional costs to the agricultural community. In fact,
> technical and financial assistance are available through federal
> programs and the Cooperative Extension Service.

3\. Detrimental Attributes

> a\. Individual actions have limited impacts. On a watershed basis, a
> comprehensive program must be developed and implemented.
>
> b\. Land treatment works best on smaller, upland watersheds rather
> than in larger river basins.

F. Onsite detention **(PP17)**

1\. Functions

a\. Onsite detention systems are typically small impoundments with
uncontrolled outlets that are created by building a dam/embankment, by
excavation, or by a combination of these.

b\. Onsite detention systems prevent or retard excessive runoff from
lands stripped of vegetation or covered by impervious surfaces
(buildings, parking lots, roads, sidewalks, etc.) from reaching a
watercourse.

c\. In part, the runoff problem can be addressed by restricting land
clearing and providing for temporary storage of runoff from a property
(U.S. Water Resources Council, 1981).

2\. Beneficial Attributes

a.  Onsite detention captures runoff to streams while at the same time
    trapping sediment and associated pollutants (i.e., improving water
    quality).

b.  When properly planned, onsite detention systems can be multipurpose,
    providing habitat for wildlife or serving as recreation fields
    during non-flood periods.

c.  Many communities can easily integrate onsite detention systems into
    existing and proposed development such as using rooftops, in
    low-lying areas, and as a part of a parking lot.

d.  When developers account for onsite detention early in the planning
    process, costs can be kept to a minimum.

e\. Communities can assess the developer for the needed additional
services such as drainage systems or pumps.

f\. Onsite detention means the developer does not profit at the expense
of others by passing excess runoff to flood downstream land uses and
require public works projects to reduce this flooding.

3\. Detrimental Attributes

> a\. In some instances, initial costs fall on the landowner who simply
> passes the costs on to the buyer or developer. On the other hand, the
> public pays for the detention system when it is part of a multipurpose
> project, such as using a recreation field to temporarily hold
> excessive runoff. Of course when integrated into a development or
> community program, the public and private sectors share land treatment
> costs.
>
> b\. Maintenance may be costly if not factored into the design and
> performed regularly. Consequently, without proper care a detention
> system loses its effectiveness.

c\. To maximize benefits and reduce additional flooding projects must be
designed and coordinated with similar actions in the watershed. Improper
design, usually of an undersized basin, can actually increase runoff by
combining peak flows with other runoff.

d\. Some communities require onsite detention systems be fenced or
screened to reduce liability. However, some detention basins are either
dry except during flood (recreation fields or water features) and are
integrated into the land use plan. Communities may not require fencing
for such features.

**Objective 19.2 Explain the beneficial and detrimental attributes of
nonstructural mitigation practices**

**Remarks:**

I. Nonstructural measures -- general (PP18)

A. Nonstructural measures are practices or approaches that

1\. Modify the susceptibility to flood damage and disruption.

> or

2\. Modify the flood impact on the individual and the community.

B. Nonstructural measures keep people and development that may be
damaged out of the flood hazard area or makes such activities more
resistant to damage.

C. Along these same lines, nonstructural measures can reduce the
financial and social impacts of flooding through programs that involve
little or no construction and have a low capital cost (U.S. Water
Resources Council, 1981).

D. Nonstructural measures are traditionally grouped into two categories.
(U.S. Water Resources Council, 1981, p. 30) **(PP19, Nonstructural
Measures):**

1\. Modify susceptibility to flooding

> a\. Floodplain regulations
>
> b\. Development and redevelopment
>
> c\. Warning and preparedness
>
> d\. Flood proofing

2\. Modify impact of flooding

> a\. Flood insurance
>
> b\. Relief and recovery

**Interactive Class Activity:**

Ask students to name specific examples in their area that are instances
of nonstructural mitigation.

II\. Nonstructural mitigation practices - specific categories

A. Floodplain regulations **(PP20)**

1\. Functions

a\. Floodplain regulations usually designate mapped flood prone areas
and limit their uses to those activities that are compatible with the
degree of flood risk, such as restricting parking along floodprone
streets **(PP21, Picture of No Parking sign).**

b\. In other words, development of flood prone lands is made more
compatible with natural processes and systems. (U.S. Water Resources
Council, 1981)

2\. For local governments to implement floodplain regulations, they
must:

> a\. Build on existing enabling statutes or home rule powers similar to
> what is used for zoning regulations or building codes;
>
> b\. Implement practical and reasonable regulations for attaining their
> goals;
>
> c\. Maps and regulations must be based on technical data that will
> satisfy a court;

d\. Not discriminate between similarly situated landowners; and

e\. Not \"take\" private property without payment of just compensation.
(U.S. Water Resources Council, 1981)

3\. Beneficial Attributes

> a\. Floodplain regulations are flexible and allow for integrating
> economic, environmental, and social values.
>
> b\. Floodplain regulations can become effective quickly, thereby
> reducing the potential for loss of life and property damage almost
> immediately.
>
> c\. Federal, state, and local agencies can usually provide technical
> information needed for floodplain regulations.
>
> d\. Floodplain regulations can prevent unwise development and stop or
> slow actions as the community plans for other activities. At the same
> time they protect buyers when they purchase property and structures in
> floodplains.
>
> e\. The community's cost of floodplain regulations is minimal when
> compared to the impacts of a flood.
>
> f\. Floodplain regulations protect the ability of floodplains to carry
> floodwaters, prevent increases in flood heights, or not otherwise
> contribute to flooding problems.
>
> g\. Flood regulations help contain the costs of emergency operations,
> relief, evacuation, and restoration.
>
> h\. Government action reduces the need for future expenditures for
> construction, operation, and maintenance of reservoirs, levees, and
> other flood control measures.
>
> i\. When structures are damaged by a flood or other disaster or have
> been remodeled (including expansion), the structure must be brought
> into compliance with the most recent statutes or codes.

j.  Finally natural floodplain values and functions are preserved.

4\. Detrimental Attributes

a\. This is not the best method for correcting existing problems because
regulations usually exempt existing development from immediate
compliance.

> b\. Unfortunately, local floodplain regulations may be easily changed.
> Modifying federal programs such as the National Flood Insurance Act
> will not be as readily modified.
>
> c\. Landowners may perceive monetary losses if the regulations prevent
> the land from being used for development. Research indicates that the
> loss in value, however, is greater from actual flooding.
>
> d\. Floodplain regulations have little impact in areas of slow or no
> growth. This is the time to adopt them as there is less opposition.
>
> e\. Communities adopt the minimal regulations required by the NFIP and
> assume they have a good program. It should be remembered that the NFIP
> is a minimum standard. In order to have a good program each community
> should design a flood damage reduction program that fits their
> location and is in compliance with the NFIP.

B. Development and Redevelopment Policies. **(PP22)**

1\. Functions

a\. Local governments can encourage and direct development and
redevelopment away from floodways and floodplains (U.S. Water Resources
Council, 1981). For example, they can zone the floodplain as low density
or open space while zoning non-floodplain land for commercial and high
density development.

b\. For example, placing schools, government buildings, and critical
facilities outside of floodprone areas draws associated, dependant
businesses away from floodplains.

c\. Development policies can tie future development to comprehensive
community plans and require that adverse impacts be mitigated before the
development can proceed.

d\. To address flooding, local governments may:

1)  Place signs identifying floodplains and giving depths of previous
    floods.

2)  Require deeds give the floodplain designation of the property, such
    as an A zone or a V zone;

3)  Tax floodplains in a way that encourages their use as open space or
    for low-density development.

4)  Offer tax credits for mitigation activities, such as flood proofing,
    elevating, or relocating.

5)  Buy properties as either a part of their mitigation plan, when a
    community locates a flood servitude or as part of another project
    such as upgrading a thoroughfare **(PP23, Development and
    redevelopment examples).**

2\. Beneficial Attributes

a\. Local governments can control the construction of utilities, sewer
and water service, and highways onto floodplains and establish limits
that restrict encroaching into channels and floodways, thereby reducing
the need for repair and replacement after a flood.

b\. When comprehensive community plans are developed, acquired land can
be used as open space for parks and storm water detention ponds.

c\. Acquisition and relocation removes the structures from the
floodplain. It no longer is subject to damage.

d\. Comprehensive planning should prevent adverse impacts and losses
resulting from future development and reduce the community's liability
for actions that might allow development that results in adverse impacts
on other properties.

3\. Detrimental Attributes

a\. Cultural enclaves may lose their identity if individuals are
dispersed to sites outside the floodplain. Once they leave, they may no
longer associate with traditional symbols of the community, such as
churches, fraternal/social halls, cemeteries, etc.

b\. People may leave the community even if the cultural enclave
maintains its identity.

c\. This option can be expensive if the property is simply cleared for
open space. Coordinating with other community programs and goals can
reduce costs.

C. Warning and preparedness **(PP24)**

1\. Functions

a\. Forecast and warning models help the National Weather Service, River
Forecast Centers, local governments, and private companies estimate the
projected severity and schedule of a flood. Much of the basic data need
for these models are from USGS river stage gauging stations **(PP25,
River Stage Recorder)** located throughout a watershed.

b\. Flood warnings and preparedness (planning for floods **(PP 25)**
give communities and individuals time to take action in anticipation of
rising waters. For example, when exceptional precipitation is
anticipated or in regions characterized by flash floods, people may
evacuate from the most dangerous locations by climbing up the valley
walls to escape high velocity flows, which have a history of loss of
life.

c\. Flood warnings give potential victims a chance to reduce or prevent
flood damages to their property by:

1)  Removing or elevating a home's contents (furniture, appliances,
    personal possessions) or commercial inventories, or

2)  Protecting valuables by sand bagging, installing temporary walls,
    closing openings, or patrolling levees.

d\. Warning systems for entire watersheds are getting more common and
now give real-time information from gauging stations over the Internet
**(PP25).**

e\. Information gets to the general public from local sources, such as
TV weather segments during the regularly scheduled news time,
interrupted broadcasts, and newspapers.

2\. Beneficial Attributes

a\. By giving communities and individuals time to prepare, warnings help
save lives and reduce property damage.

b\. Early information guides decision makers when distributing sand,
sandbags, and other emergency protection materials.

c\. Dam and levee boards use this information for the safe operation and
protection of their structure.

d\. However, collecting needed information on precipitation, river stage
readings, and duration, can be expensive unless an agency organizes
volunteers to record and transmit information. Although new automatic
recording instruments are in place at some locations, the volunteer may
never be replaced. \\

3\. Detrimental Attributes

a\. Vandalism of real-time gauges is a problem. Stealing or using them
as targets can eliminate an important source of data when they are most
needed. Consequently, the stations may be inoperable during a critical
period as they are expensive to install, update, operate, and replace.

b\. Because the initial costs for a system (setup, gauge acquisition and
installation, monitoring networks) are expensive, federal budgets are
restricted, and local matches are almost impossible to obtain, only a
limited number of watersheds have sufficient stations to provide needed
data for models. Budget woes are resulting in a decrease in gauges.

c.  Storms may interrupt the power and telephone networks. As a result
    even through volunteers have collected much needed data they cannot
    transmit it during or immediately after a storm.

d.  Storms may also wash out or destroy a gage.

e\. Operating and testing a warning system and forecast model can be
expensive and time consuming.

D. Flood proofing (**PP26, Floodproofing)** (U.S. Water Resources
Council, 1981)

1\. Functions

a\. Flood proofing may be viewed in two ways:

1)  As a group of techniques used to keep water out of buildings or to
    reduce damages caused by water, and

2)  As techniques that require human intervention, i.e., permanent
    measures, contingent or standby measures, or emergency measures.

b\. Existing buildings and facilities can be retrofitted with watertight
doors and water-resistant materials **(PP27, Elevated house and elevated
Burger King).** However, it is usually more cost effective to flood
proof during initial construction.

c\. Dry flood proofing (watertight closures, sealant on walls, plastic
sheeting) keeps the water away from people or out of a building

d\. On the other hand, wet flood proofing allows the water to enter a
building. Water-resistant materials and practices, removal of contents,
raising appliances (furnace, water heater, washer/dryer) above the flood
level, or limiting the use of space all reduces flood damages.

> e\. Permanent flood proofing measures can be integrated into a
> structure in ways that obscure their visual impact **(PP 28,
> Floodwalls and flood resistance floor tiles).**

1)  Examples include sealing openings with bricks or other flood
    resistant materials, elevation, relocation, or acquisition.

2)  These usually do not require any human intervention for them to be
    effective.

f\. Flood proofing is most appropriate for existing structures on
floodplains where inundation is shallow, infrequent, and has low
velocity.

g\. Contingent or standby measures are installed before an expected
event and are ready for use during a flood.

> 1\) Examples: panels across doors or openings, window coverings, walls
> and pumps. However, to make these effective someone must operate them.

h\. Emergency measures are implemented during a flood and are most
effective when operated according to a plan.

> 1\) Examples: sandbags, temporary walls and pumps, removal of
> contents, raising contents. Major efforts by individuals or
> communities are necessary for these to be effective.

2\. Beneficial Attributes

> a\. Flood proofing is more applicable to commercial structures.
> Businesses can afford engineers or architects to design a project that
> is professionally installed.

b\. Generally, commercial structures are better able to withstand
floodwaters. In addition, the potential benefits are high relative to
the costs of flood proofing.

c\. Damages can be prevented to a prescribed level and on a selective
basis, such as a specific structure or activity (relocating or elevating
a hot water heater or A/C unit).

d\. In some instance such as raising a washer and dryer on cement blocks
flood proofing is easy, inexpensive, and quick.

e\. Flood proofing also reduces the disruption of activities, helps
maintain essential services during and after a flood, and contributes to
faster post-flood recovery.

f\. Flood proofing is applicable to individual units, one building or a
small cluster of structures, unlike projects such as dams and levees
that protect large areas.

3\. Detrimental Attributes

a\. Similar to dams and levees flood proofing can instill a false sense
of security, thereby encouraging inappropriate or unwise uses of
buildings or floodplains.

b\. When floodwaters exceed the level of protection (dry flood proofed
to two feet, but the flood is 2.5 feet), costs can be significant. In
fact, dry flood proofing of residential structures is only recommended
to two feet of flooding.

c\. If flood-proofing techniques are improperly applied, water pressure
against the structure may cause its collapse.

d\. Even though flood proofing can protect critical facilities
(hospital, fire station, police station), these facilities may not be
operable if they cannot be reached because the roads are impassable -
and during an emergency when they are most critical.

e\. Finally, flood proofing can be costly. For example it may be better
to demolish and rebuild a structure rather than elevate a slab-on-grade
foundation.

f\. Only the structure is protected. As people move to or from the
structure they must cross flooded lands.

E. Flood insurance **(PP29, Flood Insurance)** Flood insurance was
discussed in detail in Session 18.

1\. Functions

a\. The Federal government provides property owners anywhere within the
limits of a participating community the opportunity to purchase flood
insurance for structures and contents (Catalog of Federal Domestic
Assistance, 97.022).

b\. Flood insurance is available through the National Flood Insurance
Program at FEMA, now a division within the Department of Homeland
Security.

c\. To participate, the community must adopt and enforce floodplain
management measures applicable to the Special Flood Hazard Area **(PP30,
Lake Charles FIRM).** An approved regulatory program is designed to
reduce future flood damages. Flood insurance is obtained through private
property insurance agents.

2\. Beneficial Attributes

a\. Nationally, by 2003 over 19,500 of 22,000 communities with
identified floodplains participate in the National Flood Insurance
Program.

b\. Congress has established the NFIP as a self-supporting program.
Consequently, administrative costs, mapping, and other NFIP expenses are
paid through insurance premiums and fees from map revision requests.
This reduces the costs to the taxpayer for disaster assistance.

c\. Insurance claims, unlike loans (principle plus interest), do not
have to be repaid.

d\. As of 2005 total building coverage available on a single-family
dwelling is \$250,000 plus contents (insurance coverage limits of
\$100,000) while grants are very small (sometimes only \$10,000).

e\. Similar to all insurance programs the NFIP spreads the cost of
insurance through time and over and across a large number of properties
that are at risk.

3\. Detrimental Attributes

a\. To be eligible for flood insurance a property owner must maintain
their flood insurance policy and pay the premiums.

b\. Communities must enforce floodplain regulations on how properties
within the Standard Flood Hazard Area may be used or constructed or
reconstructed.

c\. Does not reduce damages. To gain lower premiums owners are
encouraged to reduce their exposure. The Community Rating System does
the same thing for communities.

F. Relief and recovery **(PP31)**

1\. Functions

a\. Relief and recovery efforts from the public and private sectors help
the individual, business owner, and community after a flood **(PP32, Red
Cross Truck).**

b\. Relief and recovery measures include cleanup, resumption of
services, application of federal and state disaster aid normally on a
75/25 cost share basis.

c\. In addition, tax adjustment may allow credits or deductions for the
costs of repairs and rehabilitation. Creative governments can use tax
adjustments to influence how one rebuilds or uses flood prone areas.

d\. The Federal government provides loans and grants through several
programs. These will be discussed in more detail in Session 20 next
week.

e\. Communities with a recovery and mitigation plan are more effective
in implementing post flood recovery in the shortest possible time.
Important elements in this plan are provisions to mitigate structures at
risk and eliminate unwise redevelopment on floodprone lands, thereby
minimizing future flood losses.

2\. Beneficial Attributes

a\. Organized response and recovery initiatives minimize interruption of
businesses and disruption of utilities and transportation networks.

b\. During and after a flood, many federal and state programs and
nonprofit organizations, e.g. Red Cross, can assist with debris removal,
shelter and feeding victims, and rehabilitation of public services.

c\. During recovery, the local government may be presented an
opportunity to eliminate flood damaged development by elevating,
floodproofing them or buying them and relocating the victims. Finally,
structures can be rebuilt in ways that minimizes future flood losses.

3\. Detrimental Attributes

a\. Unless government takes the time to use tax credits and deductions
to guide redevelopment of floodplains these potential incentives will
not provide protection against future flood damages. Redevelopment
property without proper mitigation simply allows for the continuation of
the damage-rebuild-damage cycle of the past.

b\. In fact, poorly structured tax adjustments may encourage continued
unwise use of floodplains or even more development.

c\. Effective recovery requires forethought as expressed in a plan.
Unless the community has a strategy for debris clearance, restoration of
utilities, infrastructure, and public services victims face a protracted
period of recovery.

G. General concerns about nonstructural measures (ASFPM, 2001, p. 50)
(**PP 33, Nonstructural Measures)**

1\. Acquisition and relocation are often done piecemeal, leaving what is
called a checkerboard pattern of vacant lots and buildings that either
didn\'t qualify for the program or whose owners did not want to move.

2\. Elevation and flood proofing projects still leave buildings
surrounded by floodwaters during a flood.

a\. Occupants often try to ride out the flood or get to or from their
properties during high water, requiring significant police and fire
protection costs.

b\. The building may be isolated and without utilities; therefore
temporarily unusable.

3\. Owner-designed measures (if allowed), especially dry flood proofing,
may not adequately account for all forces that floodwaters place on a
building.

a\. This can result in severe structural damage to the building.

4\. The streets, utilities, and other infrastructure that serve an
elevated or flood proofed building are still exposed to flood damage and
public costs for those damages.

**Objective 19.3**

Complete the Module examination.

**Remarks:**

A.  The Module 4 examination may be distributed at the end of class to
    be completed at home. If it is distributed, a few minutes should be
    allowed for explanation.

B.  The instructor may also distribute the examination during the next
    session to be completed with in class.

**Handouts**

**Handout 19H1**

**NO ADVERSE IMPACT (NAI)** floodplain management is an approach that
insures the action of any community or property owner, public or
private, does not adversely impact the property and rights of others
(ASFPM, 2003, p. 3).

**NONSTRUCTURAL APPROACHES** - includes all other adjustments (e.g.,
regulations, insurance, etc.) in the way society acts when occupying or
modifying a floodplain (FEMA, 1986, p. IV-1). Nonstructural approaches
generally are applied to individual structures, as opposed to structural
measures that are generally adjust the waterway or floodplain to fit
human needs.

**NONSTRUCTURAL MEASURES** - A term originally devised to distinguish
techniques that modify susceptibility to flooding (such as regulation,
floodplain acquisition and flood proofing techniques) from the more
traditional structural methods (such as dams, levees, and channels) use
to control flooding (L.R. Johnston, 1992, p. C-7).

**NONSTRUCTURAL MEASURES** - All floodplain management measures
excepting structural flood control works. Examples of nonstructural
measures are flood warning/preparedness systems, relocation, flood
proofing, regulation, land acquisition, and public investment policy
(United States Water Resources Council, 1981, p. A - 4).

**NONSTRUCTURAL MEASURES** - fall into two broad categories, those that
modify the susceptibility to flood damage and disruption, and those that
modifies the impact of flooding on individuals and on the community
(U.S. Army Corps of Engineers, 1983, p. 13).

**STRUCTURAL APPROACHES** - adjustments that modify the behavior of
floodwaters through the use of measures such as public works, dams,
levees and channel work (FEMA, 1986, p. IV-1).

**STRUCTURAL MEASURES** - Measures such as dams, reservoirs, dikes,
levees, floodwalls, channel alterations, high flow diversions and
spillways, and land treatment measures designed to modify floods (L.R.
Johnston Associates, 1992, p. c-9).

**STRUCTURAL MEASURES** - Flood control works such as dams and
reservoirs, levees and floodwalls, channel alterations, seawalls, and
diversion channels which are designed to keep water away from specific
developments and/or populated areas or to reduce flooding in such areas
(United States Water Resources Council, 1981, p. A-5).

**STRUCTURAL MEASURES** - direct flood waters into desired paths (U.S.
Army Corps of Engineers, 1983, p. 13).

**References**

The Federal Interagency Floodplain Management Task Force. 1994. *A
Unified National Program for Floodplain Management 1994.* FEMA 248/June.

The Federal Interagency Floodplain Management Task Force. 1996.
*Protecting Floodplain Resources. A Guidebook for Communities*. FEMA
268/June. 2nd Edition

Federal Emergency Management Agency. 2002. *Getting Started. Building
Support for Mitigation Planning. State and Local Mitigation Planning
How-to Guide.* FEMA 386-1. September.

Federal Emergency Management Agency and the National Park Service. 1994.
*A Multi-Objective Flood Mitigation Plan. Vermillion River Basin, South
Dakota.* FEMA, Region VIII and the Rivers, Trails and Conservation
Assistance Program of the National Park Service, Rocky Mountain Region.
Denver, CO.

Federal Emergency Management Agency and the National Park Service. 1994.
*A Multi-Objective Planning Process for Mitigating Natural Hazards.*
FEMA, Region VIII and the Rivers, Trails and Conservation Assistance
Program of the National Park Service, Rocky Mountain Region. Denver, CO.

Godschalk, D.R., T. Beatley, P. Berke, D.J. Brower, E.J. Kaiser, C.C.
Bohl, R.M. Goebel. 1999. \"Chapter 13. Mitigating Natural Hazards:
Planning for Sustainable Communities.\" IN: *Natural Hazard Mitigation.
Recasting Disaster Policy and Planning.* Washington, D.C.: Island Press.
Pp. 525-552.

National Science Foundation. 1980. *A Report on Flood Hazard
Mitigation*. Washington, D.C. September. 253 p.

Paterson, R.G. 1998. \"The Third Sector: Evolving Partnerships in Hazard
Mitigation.\" IN: R.J. Burby (ed.) *Cooperating with Nature. Confronting
Natural Hazards with Land-Use Planning for Sustainable Communities.*
Washington, D.C.: Joseph Henry Press. Pp. 203 - 230.

The Task Force On The Natural And Beneficial Function Of The Floodplain.
2002. *The Natural And Beneficial Functions Of Floodplains Reducing
Flood Losses By Protecting And Restoring The Floodplain Environment.* A
Report For Congress. FEMA 409, June.

United States Army Corps of Engineers. 1983. *Seminar Proceedings.
Implementation of Nonstructural Measures.* Civil Works Directorate, Ft.
Belvoir, VA, November 15-17, 1982. Policy Study 83-G520.