:7 -:-= 

=7 = 

L--



The Federal Interagency Floodplain Management Task Force was established 
in 1975 to carry out the responsibility of the President to prepare for the Congress 
a Unified National Program for Floodplain Management. Since 1982 
the Task Force has been chaired by the Federal Emergency Management 
Agency, Membership of the Task Force consists of the Departments of 
Agriculture, Army, Commerce, Energy, Housing and Urban Development, 
Interior, and Transportation; the Environmental Protection Agency; and the 

Tennessee Valley Authority. 

Design: Mike Campbell, Publications Department,
Universityof Colorado.
Cover photo. Bob Cox, Floodplain ManagementSction,
Louisiana Department of Transportation
and Development.



-

FLOODPLAIN MANAGEMENT 

IN THE 

UNITED STATES: 

AN ASSESSMENT REPORT 

Volume 1 

SUMMARY 

Prepared for
The Federal Interagency
Floodplain Management
Task Force


Prepared by
The Natural Hazards
Research and Applications
Information Center,
University of Colorado at Boulder


(Contract No. TV-72105A) 

1992 


Contents


Preface ......................................... 4
Acknowledgments ......................................... 5


Part I: The Nation's Floodplains, Their Value, and Their Floods 

Floodplains............ ............................. 8


The Value of Floodplains ......................................... 8
Water Resources ..... .................................... 9
Flood and Erosion Control .................................... 9
Surface Water Quality Maintenance ............................ 10
Groundwater Supply and Quality .............................. 10


Living Resources ............................. ............ 10
Wetlands ......................................... 10
Riparian Systems ......................................... 11


Cultural Resources .......................... ............... 12


Floods ......................................... 13
Riverine Flooding . ......................................... 13
Flooding from Surface Runoff ................................... 14
Coastal Flooding and Erosion ................................... 14
Ground Failure ......................................... 15
Fluctuating Lake Levels ........................................ 16


Floodplain Losses ......................................... 16


Loss of Life and Property ...................... . .............. 18


Loss of Natural and Cultural Resources ........................... 19


Part II: Managing Floodplains to Reduce Losses 

The History of Floodplain Management ............................. 24
1900-1960:The Structural, Federal Era .......... .................. 24
1960s: A Time of Change ................................. ..... 24
1970s:The Environmental Decade ............................... 26
1980s: Continuing Evolution ..................................... 26


The Management Framework ..................................... 26
The Federal Government ....................................... 28
State Government ......................................... 28
Local Government ......................................... 29
Regional Entities .......................................... 29
The Private Sector ......................................... 30


Modifying Susceptibility to Damages and Disruption ...... ............ 30
Regulations ......................................... 30
Development and Redevelopment Policies ........ ................. 32
Disaster Preparedness ......................................... 32
Flood Forecasting, Warning, and Emergency Plans ...... ............ 33
Floodproofing and Elevation ................... ................ 33


Modifying Flooding ......................................... 34


Investment in Flood Control .................................... 35


Dams and Reservoirs ......................................... 36


Dikes, Levees, and Floodwalls ................................... 37


Channel Alterations ......................................... 38


High Flow Diversions ......................................... 38


Stormwater Management ..... .......................... I ... 38


Shoreline Protection ......................................... 38


Land Treatment Measures ...................................... 39



Modifying the Impacts of Flooding ................................. 40
Information and Education ..................................... 40
Flood Insurance .............................................. 40
Tax Adjustments .............................................. 42
Flood Emergency Measures ..................................... 43
Disaster Assistance ............................................ 43
Postflood Recovery ............................................ 45


Restoring and Preserving the Natural and Cultural
Resources of Floodplains .......................................... 45
Regulations .................................................. 46
Development and Redevelopment Policies ......................... 47
Information and Education ..................................... 48
Tax Adjustments .............................................. 48
Administrative Measures ....................................... 49


Part III: The Effectivenessof Floodplain Management 

Perception and Awareness of Floodplain Losses ....................... 52
Recognition of Risk ........................................... 52
Awareness of the Value of Natural Floodplains ...................... 53


Knowledge, Standards, and Technology .............................. 54
Climate Change and Weather Forecasting ......................... 54
Streamflow Data .............................................. 54
Hydrology and Hydraulics...................................... 54
Flood Forecasting and Warning .................................. 55
Soil Identification and Mapping ................................. 55
Mapping Flood Hazards ....................................... 56
Understanding and Mapping Wetlands ........................... 57
Understanding Natural and Cultural Resources .................... 57
Remote Sensing Techniques ..................................... 57
Geographic Information Systems................................. 57
Regulatory and Design Standards ................................ 58


Judicial Support for Floodplain Management .................... I .... 58
Constitutionality of Regulations .................................. 58
Liability for Flood Damages ..................................... 59
Avoiding Legal Problems ....................................... 59


The Present and the Future ....................................... 60
Overview.................................................... 60
Overall Effectiveness........................................ 60
Achievements to Date ....................................... 60
The Need for Specified Goals ................................. 61
The Need for a Comprehensive Data Base ...................... 61


The Effectiveness of Management ................................ 61
Allowing for Different Approaches ............................. 61
Coordination Among Government Agencies..................... 62
Providing for Local Conditions................................ 62


The Effectivenessof Floodplain Management Strategies and Tools..... 63 
Modifying Susceptibility to Flood Damage and Disruption ......... 63 
Modifying Flooding ......................................... 63 
Modifying the Impact of Flooding on Individuals 
and the Community ....................................... 64 
Restoring and Preserving the Natural and Cultural Resources 
of Floodplains ............................................ 64 

Conclusion ..................................................... 65


Retrospect and Prospect 
-GilbertF White ................... .......................... 67 


Preface


The coastal and riverine floodplains of the United States are highly desirable 
and rewarding sites for most kinds of human activities and contain a wealth 
of natural and cultural resources of immense importance and value to the 
nation. Yet they are the source of costly and frequently unnecessary losses of 
human life and property as well as losses of resources afforded by floodplain 

environments. 

In terms of areas affected and annual economic losses, flooding remains 
the greatest and most persistent natural disaster facing our nation, despite 
concerted efforts at all governmental levels and within the private sector to 
moderate, account for, or adjust to the flood risk. These efforts go back at 
least to the turn of this century, when initially they were focused on controlling 
the paths of flood waters. Other flood loss reduction strategies and a 
myriad of programs have since evolved to complement these initial efforts. 
More recently, increased attention has been given to preserving the natural 
functions and resources of floodplains. 

This assessment of floodplain management in the United States was 
commissioned in 1987 by the Federal Interagency Floodplain Management 
Task Force. Its purpose was to provide an evaluation of floodplain management 
activities in order to report to the public and to the Congress on progress 
toward implementation of "A Unified National Program for Floodplain 
Management" [Section 1302(c) of the National Flood Insurance Act of 1968]. 
Thus, it is a compilation of available information concerning the nation's floodplains, 
experience with tools and strategies to reduce losses of life, property, 
and environmental resources, and a perspective of what has been 
accomplished. 

The assessment is presented in two parts. This summary report (Volume 
1) presents the salient information and findings of the full report (Volume 
2) and reflects both its content and organization. Sources of information 
for Volume I and additional detail, explanation, and analysis can be found in 
the full report. 

A concerted attempt was made to compile information and available 
data from numerous sources in an attempt to describe, evaluate, and provide 
for a balanced view and account of the various activities and management 
approaches. However, all accounts and contributions to floodplain management 
may not be adequately documented in this assessment due to the lack of sufficient 
information or usable data regarding certain subjects or topics. Nevertheless, 
task force member agencies concurred with the content of this document 
and believe that this assessment provides the most comprehensive 
statement available and a foundation for action to improve effectiveness of 
floodplain management in the United States. It is commended to all parties 
who make decisions affecting floodplains and their occupants and to those 
having an interest in learning more about this subject. 

Frank H. Thomas 

Federal Emergency Management Agency 

Chair, Federal Interagency Floodplain Management Task Force 


Acknowledgments 

This summary was prepared under the direction of the Natural Hazards 

Research and Applications Information Center, University of Colorado at 

Boulder, and is based on the full report prepared by L.R. Johnston Associates. 
Both reports resulted from contractual arrangements with the Tennessee 
Valley Authority, which managed the national assessment effort for the Interagency 
Task Force. Principal authors of the two reports were Jacquelyn L. 

Monday and the late Larry R. Johnston, respectively. 

Countless others contributed support, information, and ideas. The 
Federal Interagency Floodplain Management Task Force provided funding 
for this study, and an Advisory Committee of the Task Force was created to 
provide direction and guidance throughout the work effort, including review 
of draft reports. The Association of State Floodplain Managers and the Association 
of Wetland Managers devoted a portion of their annual conferences to 
provide information and input to the process. A National Review Committee, 
comprised of recognized experts and chaired by Gilbert F. White (one of the 
true pioneers of the floodplain management movement that began around 
50 years ago) added valuable insight and proposed an ActionAgenda. Many 
individuals, including those representing government agencies and professional 
and nonprofit organizations, also made important contributions by 
providing information, data, insights, and perspectives. 

James M. Wright 
Tennessee Valley Authority 
Project Manager 


Al1 

t!31h11;j~~~~~~~~~~~~~~~~~~~~W 

JPART'7 

i~A~AND FLOODS

THEIR 


FLOODPLAIN MANAGEMENT 

Floodplain Afan7ac8'cncrn iL a decisionma inog 
proc s the S'oalgoc which Il achieisc _e useOic' 
of the nation 's /oodp/ains. I Hise 9-any

use I 
activity or set of actic it c that 9ccornpeclhle eithl/

1/c 
the cisk to natural reources (natural and bencficial 
finction o ffloodplaiisx) and humanion 
IScOUiliAs (life and propert;). Compatibility is 
aichcived though the strategies and tools of the 
(rnified Natiional n

Program for liodplcic 

Afanagcerrcccct. 

Previous page: The Yellowstone River and Hayden Valley 
in Yellowstone National Park are a river and floodplain 
relativelyundisturbed by hurnan intrusion. 

_ 

Floodplains


Floodplains are the lowlands adjoining the channels of rivers, streams or 
other watercourses, or the shorelines of oceans, lakes, or other bodies of standing 
water. They are lands that have been or may be inundated by flood water. 
Floodplains are shaped by dynamic physical and biological processes: climate, 
the hydrologic cycle, erosion and deposition, extreme natural events, and 
other forces.The products of the complex interrelationships of these processes 
are many of the nation's most beautiful landscapes, most productive wetlands, 
and most fertile soils, along with rare and endangered plants and animals, and 
sites of archaeologic and historic significance. Throughout our history, rivers 
and other bodies of water have been highways for exploration, migration, and 
commerce and have been used as disposal systems for the byproducts of industrial 
society. Almost all major cities are located on a river or at the mouth of 
a river. Most smaller communities have at least one stream that helps define 
local character and is an important source of community identity. 

The Floodplain with Floodway 

.. Floodwaya
Flood Fringe Flood Fringe


I 

"100-Year"Floodplain 

Channel 

The U.S. Water Resources Council estimated in 1977 that about 7%O,or 

178.8million acres, of the total area of the United States, including Alaska and 
Hawaii, Puerto Rico, and the Virgin Islands, was within the 100-year floodplain. 
The Federal Emergency Management Agency, in a 1991 study that 
examined nearly 17,500 mapped floodprone communities in the 50 states and 
the District of Columbia, estimated that there are about 94 million acres. The 
largest areas of floodplain are in the southern part of the country, but the 
most populous are along the north Atlantic coast, in the Great Lakes region, 
and in California. 
The Value of Floodplains 

In their natural state, floodplains have enormous but often unrecognized 
value. These complex dynamic systems contribute to the physical and biological 
support of water resources, living resources, and cultural resources. 

Floodplains are important to the nation's water resources because they provide 
natural flood and erosion control, help maintain high water quality, and 
contribute to sustaining groundwater supplies. Floodplains have living, or bio


logic, resource value, because they support a wide variety of flora and provide 


habitat for fish and wildlife. The cultural resources of floodplains include the 

maintenance of a harvest of natural products, placesfor recreation, scientific 

study, and outdoor education, and sites of historic and archeological interest. 

Although the value of these resources is now well recognized and most 
of the processescontributing to them reasonably wellunderstood, it has proven 
difficult and sometimes impossible to assign economic values to the functions 

served and benefits provided by floodplains. 

Water Resources 

Water can be put to human use either while it is in the stream or other 
water body or when it is diverted and used elsewhere. Offstream, surface 
water can be used for irrigation, for industrial and municipal purposes, and 
energy production. These uses reduce the flow or level of water, at least temporarily, 
and inevitably degrade its quality somewhat. Instream uses of water 
include navigation, fish and wildlife propagation, waste transport, hydropower 
generation, agricultural and industrial uses, recreational activities, and supplying 
drinking water. Instream uses usually require a minimum flow or 
water level and hence tend to compete with offstream uses. 

Flood and Erosion Control 

Natural, unaltered floodplain systems can reduce flood velocities, reduce 
flood peaks, and reduce wind and waveimpacts because their physical characteristics 
affect flood flows and, typically, provide space for the dispersal and 
temporary storage of flood waters until the natural drainage can carry them 
away.This natural function obviously can reduce the potential damages and 
loss of life from floods. One acre of a floodplain can store about 325,000 
gallons of water if flooded to a depth of only one foot. Floodplain vegetation, 

Natural and Cultural Resources of Floodplains 

Water Resources 

Natural Flood and Erosion Control Surface Water Quality Maintenance 

* Reduce flood velocities * Reduce sediment loads 
* Reduce flood peaks * Filter nutrients and impurities 
* Reduce wind and wave impacts * Process organic and chemical wastes 
* Stabilize soils * Moderate temperature of water
0 Reduce sediment loads
Maintain Groundwater Supply and Quality 

* Promote infiltration and aquifer recharge 
* Reduce frequency and duration of low flows; 
i.e. increase/enhance base flow 
Living Resources 

Support Flora Provide Fish and Wildlife Habitat 

* Maintain high biologicalproduc-* Maintain breeding and feeding grounds 
tivity of floodplain and wetland * Create and enhance waterfowlhabitat 
vegetation * Protect habitat for rare and 
* Maintain productivity of natural endangered species
forests
* Maintain natural crops 
* Maintain natural genetic diversity 
Cultural Resources 

Maintain Harvest of Natural and Provide Opportunities for Recreation 

Agricultural Products * Provide areas for active and 

* Create and enhance agricultural lands consumptive uses 
* Provide areas for cultivation of fish * Provide areas for passive activities
and shellfish * Provide open space values
* Create and enhance forest lands * Provide aesthetic values 
* Provide harvest of fur resources 
Provide Areas for Scientific Study and Outdoor Education 

* Provide opportunities for ecological studies 
* Provide historical and archaeological sites 
Coastalbarriersare constantlychanginglandforms. They 
protectmuchof the Atlanticand Gulf coast from thedirect 
effects of high water, waves, currents, and severestorms. 

Development on a coastal barrier, Grand Isle, Louisiana. 


WETLAND FLOODPLAINS 
HELP MAINTAIN WATER QUALITY 


* Studies of heavily polluted watersflowing through 
Tinicum Marsh in Pennsylvania have revealed sig-
nificant reductions in biological oxygen demand, 
phosphorous, and nitrogen within three to five hours. 

* The value of Georgia's 2,300-acre Alcovy River 
Swamp for water pollution control has been estimated 
at $1 million a year. The bottomnandforested 
wetlandsalong the river have been shown to filter 
impurities from flood waters. 
N:* t hi 0 0 
'StI ~ i;ot 
Riparianhabitatssustainecagstemsthat include many 
*artgemammals such as bear, white-tailed deer, and 
caribou. 
White-tailed Bqy, Florida. 


deer, St. Andrews 

especially in wetlands, can reduce erosion by binding the soil with its root sys


tems. Moreover, friction between the vegetation and the water dampens waves 
and reduces current velocity. Coastal barriers-elongated, offshore formations 

of sand and other unconsolidated sediments lying generally parallel to mainland 
coastlines-protect large portions of the coast, including estuaries, bays, 
and wetlands, from the direct effects of high water, waves, and currents 
caused by both normal and storm conditions. 

.1.1 

r ~~~~h~ 

Floodplainsand wetlands not only help maintain water quality, they also provide a natural environment for 
diverse species. 

Bottomland hardwood swatmp,Louisiana. 

Surface Water Quality Maintenance 

Natural floodplains can reduce the cost of waste water treatment and 
water quality maintenance; they can reduce sediment loads, process chemical 
and organic wastes, and reduce nutrients, thereby protecting the physical, biological, 
and chemical integrity of water. Floodplains buffer rivers, streams, 
lakes, and estuaries from upland sources of pollution. 

Groundwater Supply and Quality 

Conditions beneath undisturbed floodplains can facilitate the infiltration 
and storage of water, permit groundwater recharge, purify water entering the 
aquifer, reduce flood peaks, and ameliorate the frequency and duration of low 
flows in groundwater systems. These functions help maintain and improve 
conditions for municipal and private wells, wildlife, irrigation, and watering 
livestock during drought. 

Living Resources 

Floodplains are among the most productive of the planet's ecosystems. 
Because of their relative abundance of water, they provide habitat for a multitudeof 
plant and animal species, and the energy and nutrients from their 
healthy function are passed along to organisms in adjacent and downstream 
areas, 

Wetlands 

:41S < P of A >+Wetlands 

are perhaps the most prominent and familiar of floodplain 
resources. They are lands transitional between terrestrial and aquatic systems 
$:Iand are ; covered by shallow water or have a water table at or near the surface. 

all<( If 

There are slightly in excess of 100 million acres of wetlands in the 48 contiguous 
states, and the majority of these are in floodplains. Florida, Louisiana, 
and Alaska have the most wetland acreage. 

Wetlands are classified by the U.S. Fish and Wildlife Service according to 
five ecological systems, of which estuarine and palustrine wetlands are best 
known. Estuarine systems include such coastal wetlands as salt and brackish 
tidal marshes, mangrove swamps, and intertidal flats, as well as the deepwater 

habitats associated with bays, sounds, and coastal rivers. Palustrine wetlands 


account for about 90% of all U.S. wetlands. They are inland, freshwater areas 
of marshes, bogs, and swamps, and some brackish and salt marshes in arid 
and semi-arid areas. 

Wetland plants are particularly efficient converters of solar energy. Their 
major food value is achieved when they die and fragment to detritus. Numerous 
fish and wildlife species feed in marshes and swamps or on organisms that 
were produced in such areas. Some animals spend their entire lives in floodplain 
wetlands, while others use the wetlands primarily for reproduction, 

Typical Inland Wetland 

SeepageWetland Overflow DeepwaterOverflow Depressional 

on Slope Wetland Habitat Wetland Wetland 

nursery grounds, or for drinking water. About 50% of the endangered species 
in the United States require wetland habitat at some point in their life cycles; 
wetlands are crucial to the survival of the American crocodile, the manatee, 
the whooping crane, and the Mississippi sandhill crane. Both coastal and 

inland wetlands also provide valuable habitat for such furbearers as muskrat, 

beaver, otter, mink, and raccoon, as well as numerous reptiles and amphibians. 
Large mammals, such as black bears, white-tailed deer, and caribou, also find 
refuge and food in wetland areas. 

Riparian Systems 

Riparian floodplains are distinct associations of soils, flora, and fauna 
that occur in narrow strips along rivers, streams, or other bodies of water and 
depend for survival upon high water tables and occasional flooding. They are 

FLOODPLAINS AS HABITAT 

* Black ducksmgratinig in theAtlantic flyway use 
the northern salt marshesas their primary wintering 
grounds. 
* Intertidalmudfiats along the coasts are theprincipalfeeditnggrourndsfor 
migratory shorebirds,most 
shorehirdsbreed in Alaskan and other tundra 
wetlands. 
* lississipti Ricerfloodplainsare themajorresting 
and fiedinggroundsfir dAcksand geese during their 
fall and spring migrations. 
* During droughtsin the prairiepothole region, 
Ala.ikace wetlandsare heavily used/fornestingby 
North American waterfowl. 
* Hawaiin'swetlands arc especiallyimportant to 
endangeredhirds. 

* Arizona s native cottonwood-willowt,associations 
supporthitgherdensitiesand a gieater diiersity of 
breedintgbird speciesthan any other deserthabitat 
* Ihe prairiepotholeregionof the Dakotasis the 
main breedingareafor wiaterfowlin the United 
States 
* The SanPedroRiver s riparian ecosystemin 
southeasternArizona providesnesting, migratory, or 
winteringhabitatfor at last 20 raptorspeciesand 
about210)specis (f other birds.A study recorded78 
stpecesof mamimalsin thegraislands corridior 

betweenthe riparian woodlandsand adiacentmountains, 
the second-higihet 7inaminalian

diversty in the 

Etworld. 

Canvasbackduck,salt marsh, New England. 

Greatblue heron, Merrimack River NeiwHampshire. 

Healthyriparianecosystemsareessentialformaintainingthebiologicaldiversityofthe nation s flora. They 
alsoprovideaestheticpleasure. 

Wetlandvegetation,JoyceKilmerMemorialForest,NorthCarolina. L 


providenumerous 

opportunities-includinghiking,camping,huntingfi.hing, 
boatingswimming,bird-watching,picnickingjogging 
photography,ice skating, and simplyobserving 
nature. 

Riversandfloodplains recreational 

Above. Bicyclist, Boulder CreekPathway, Bouldder
Colorado.


Below:Canoer,NantahalaRiver,North Carolina. 

1_i i4i 

generally more biologically diverse than the surrounding uplands and encompass 
a broader range of moisture and soil conditions and a greater diversity 
of flora and fauna than wetlands do. The Soil Conservation Service estimates 

that there are 16million acres of riparian land along streams, canals, lakes, 
reservoirs, and tidal shorelines of rural, nonfederal portions of the United 
States. Bottomland hardwood forests also are a major riparian ecosystem, 
and they account for about 52 million acres, mostly in the South. 

Healthy riparian ecosystems provide community structure for raptors, 
safe passage corridors to water for mammals, habitat for amphibians, and 
cover and nutrients for fish. At elevations below 3,500 feet, they take the form 
of lush strips of streamside vegetation that interrupt the desert landscape. 
These linear communities provide habitat for up to 80% of the West's wildlife 

species, and are essential for maintaining its healthy fish and wildlifepopula


tions. Cottonwood groves provide a high canopy and open understory essential 
to certain birds of prey for hunting, while mesquite bosques provide lower, 
denser vegetation ideal for colonial nesting by whitewing doves. Also depen


dent on riparian habitats are grey squirrels, river otters, muskrats, summer 
tanagers, canyon frogs, tree frogs, and dove-tailed hawks. 

Arid regionfloodplains, althou4'h apparently desolate, actuall provide,habitatfor most desert wildife species. 

Channel,floodplain,and riparianhabitat,VerdeRiver, TontoNationalForest,Arizona. 

Cultural Resources 

As used in this report, the cultural resources of floodplains include their 
historic and archaeological sites, their scientific, recreational, and aesthetic 

uses, as well as the harvest of the floodplains' natural and cultivated products. 
Because water has always been basic to human survival, transportation, and 
commerce, many sites of historic and archaeological significance lie in floodplains. 
Floodplains provide opportunities for hiking, camping, hunting, fishing, 
boating, swimming, bird-watching, picnicking, jogging, photography, ice 
skating, nature observing, as well as for scientific study and research, educational 
activities, and less tangible aesthetic benefits. Floodplains can provide 
urban communities with a tremendous open-space and greenbelt resource. 

Inland floodplains are great sources of commercial timber. Much of the 

82 million acres of commercial forested wetlands in the 49 continental states 
lies within floodplains. The standing value of southern wetland forests alone 
is $8 billion. The floodplains along larger rivers are prime agricultural lands 

because of their flat terrain, abundant water supplies, and rich alluvial soils 
periodically replenished by flooding. From 1956 to 1975 about 60% of the 

U.S. commercial fish and shellfish harvest was made up of wetland-dependent 
species. Several billion dollars are generated annually from this harvest and 
from wetlands-dependent sport fishing. 

Floods


Floodplains are, by definition, lands that are formed by and continually subject 
to inundation by water. Depending on the location, topography, soils, and 
weather conditions, that flooding can take a variety of forms. Riverine floods 
can result not only from heavy rainfall and rapid snowmelt but also from dam 

and levee failure, ice jams, and channel migration. Coastal flooding can be 

caused by hurricanes, winter storms, tsunamis, and rising sea level. Individual 
storms and long-term climate variations cause flooding around lakes. 
Other floodprone areas include alluvial fans, unstable and meandering chan


nels, and areas affected by land subsidence and ground failure. In addition, 
flooding due to surface runoff and locally inadequate drainage can be a major 
problem, particularly in rapidly urbanizing areas. 

Riverine Flooding 
Riverine flooding-overflow of water from the channel onto the adjacent 
floodplain-is the most common type of flood. Hundreds occur each year in 
the United States. 

* Flashflooding occurs in all 50 states: in narrow, steep valleys, on alluvial 
fans, on denuded areas, and along urban drainage courses, usually as a 

result of high intensity,short duration storms occurring on steep gradient 

streams. Flash floods can be more dangerous than other floods because 

of their suddenness, the velocity of the water, and the large amount of
debris carried by the flood waters.


after he7vy rai. Big Thompson Canyon, CColorado,

followingflashhflood. 

July 1976 

Ju~c172,Raid ity $ohvakoaia-i djc77wu-3dead andmoe49~ 

1&s p irtydmcnp inae S r tiurnaed _ i

in pw damalla whuuerstr tewsendi4o 

Jasa i6m6ptl*yoCltt kW=a;id l o 


4 ig

J< 17, huton Pnslaui-7 da andmor tWa 200 mllo iz 

p~c~ dawewe ioln udrt, poued ihs Gofinora 

~~~~~~~~. CreK

i" 

=anyox~wi0 12+g rain inX _ o ftaflof is

inccs :Aial 

City, Miuou4 ccurthrughutate

Sq~~~eiubcr1977,Kansaspzd s4Ja~~muntans Untedtatsflbtdismos 

* Allvialfan floodingcan cause great damage because of the high veloci-
arge area c by
l ties,amounts of sediment andeis, and debwide overed revantand oses the great s hazard i the ard West 
the waters. Alluvial flood

fans occur mostly along th basee of mound 
talus mi tne western states. An estimated 15-25% Aoiuvol at o, ,ravier

of the aigd West, pafd, the Arizof 

including Los Angeles and Las Vegas, is covered by alluvial fans. 

* Unstableand meandering streamchannelsare also frequently flooded. Many of
them are the product of severaldecades of human activities, particularly
in the arid and semi-arid West. Overgrazing, mining, forestry, urbani-
zation, gravel and sand extraction, and the construction of railroads, _



Stormdrainageis a significant problem in many large 
urbanareas, particularly if development has been rapid 
and not well planned. Drainage systems must be designed 
to handle infrequent, butpotentially catastrophic, events. 

Concrete-lined carrying flood waters, 

artificial channel 
Baton Rouge, Louisiana. 

Hurricanescan result in flooding of various kinds, from 
flash flooding and slow-rise riverineflooding due to heavy 

precipitation,to coastal flooding due to storm surge. 

Quinebaug River, Putnam, Connecticut, 1955, following 
Hurricane Diane. 

Hurricanescan cause severe damage due to the combined 
effects of several agents-high winds, increased waveaction, 
heavy precipitation, storm surge, and other types of 
flooding. 

Damage near Charleston, South Carolina, following Hurricane 
Hugo, September, 1989. 

highways, dams, and irrigation facilities all have changed the vegetative 
cover, altered surface water patterns, changed the movement of sediments, 
and lowered water tables. These changes have made water 
movement during floods difficult to predict. 

* Icejams, which affect 35 states, cause a rapid rise of water both at the 
point of the jam and upstream; when the jam breaks, sudden downstream 
flooding results. Because the waters are higher and their velocities 
greater, damages usually exceed those that would have occurred 
without the jam. Additional damage can be caused by the force of the 
ice, as it builds in volume and expands overbank during the jam and 
then crashes downstream when the jam breaks. 
Flooding from Surface Runoff 

The runoff from heavy precipitation can overtax inadequate local drainage 
systems and result in flooding outside of normal floodplains. These kinds 
of flooding problems generally intensify as areas become more urbanized. 
Frozen ground and heavy accumulations of snow can exacerbate the problem. 

Coastal Flooding and Erosion 

Coastal flooding and erosion result from storm surge (the rise in the 
water surface due to barometric pressure and the piling up of water as a 
result of wind) and wave action (the combination of wave set-up and wave 
runup). The frequency and magnitude of flooding and erosion vary considerably 
across the country. 

* From 1899 to 1989 a total of 148 hurrkcanesand 135 tropical storms crossed 
or passed adjacent to the U.S. mainland. 
* Northeasters-extratropicalstorms accompanied by strong winds-cause 
flooding along the north Atlantic coast. 
* Tsunamisare sea waves generated by undersea earthquakes of over R6.5; 
they are very long-period, are of low height at sea, and can travel over 
500 mph. The entire Pacific coast of the United States, including 
Alaska and Hawaii, is subject to tsunamis. 
* Shorelineerosionoccurs either when storm surge and wave action move 
sediment offshore or when the alongshore flow of sediment is interrupted 
by natural forces or human activities. Natural erosion may be 
accelerated by partial or inadequate structural or nonstructural measures 
intended to protect short reaches of eroding shoreline-such as 
beach nourishment, artificial dunes, breakwaters, seawalls, bulkheads, 
revetments, groins, and jetties. n 
Number of Major Hurricanes Directly
Affecting the United States, 1899-1989


Source:National Hurricane Center, National Weather Service 


Ground Failure 

Areas subject to ground failure often suffer from mid flows and mudfloods, 

two forms of landslides. Urban development alters hillslope configurations 
and upsets established equilibrium, triggering the natural instability of many 
slopes and sometimes reactivating old landslides. Mud and debris may fill 
drainage channels and sediment basins, causing flood waters to suddenly 
inundate areas outside the floodplain. Mud flows and mud floods may cause 
more severe damage than other flooding because of the force of the debris-
filled water and the combination of debris and sediment. 

Both. natural and human-induced subsidencecan increase flood damage in 
areas of high groundwater, tides, storm surges, or overbank stream flow. It 
can also block or otherwise alter drainage patterns, leading to deeper or unexpected 
flooding. Subsidence occurs in at least 38 states. 

Liquefactionis a type of ground failure triggered by seismic waves passing 
through unconsolidated and saturated soil. Depending on the character of the 
soil, the amount of water, and the drainage potential, the soils may sink or 
become liquid. This can result in serious flooding of structures built on fill or 
saturated soils-as in parts of San Francisco and Anchorage. 

Mudflows and mud floodsare two typesof landslides thatcan be aggravatedby humandevelopment.Additionally,
theycan result from othernaturalhazards,suxh as earthquakes and volcaniceruptions. 
ToutLeRiver. WashinetonState,followinetheeruptionof Mt. St. Helens, May 1980. 

Natural coastalerosion can be grat~ay accelerated by wave 
aclionduring storms and hurricanes. Combinedwith inappropriateconstruction 
in coasfal areas, this natural process 

can r;sult in disaster. 

Big RockBeach, Malibu, Califibrnta,

followingPacific 
winter storm, 1983. 


Fluctuating Lake Levels 

Historically, the development of the United States has 
proceededalong the principal waterways of the nation, 

where cities have been developed and redeveloped over the 

decades. 

Pittsburgh, Pennsylvana, early 1960s. 

(Comparethis photograph with those on page 24.) 

Closed-basin lakes are susceptible to dramatic (5-to 15- foot), long-term 
fluctuations in their water levels as a result of variations in precipitation, runoff, 
and evapotranspiration. Flooding associated with this situation can last 
for years; examples of such lakes are the Salton Sea, the Great Salt Lake, and 
the Great Lakes. Short-term fluctuations can be triggered by sustained strong 
winds and by sharp changes in barometric pressure. Human activities, such 
as dredging, diversions, water consumption, and regulation by structural 
works, can also affect lake levels. 

Change In Water LevelsIntheGetLleW 

ron~~~~100-19863 (witerf lowf to0S rffg hIYI 

S00peria 4 600.62 602.24 598.2 1

Miciga-Huon578.3 5816 73 .. . . 

St. Clair 573.40 576.69 56.6 { 53 0, 
Erie 570W50 5737 ~A . . 

Levsae r~recedto Initernationara aksDtx 

Floodplain Losses 

Throughout the history of the United States, the prevailing view has been 
that humans should use and modify the natural environment, including floodplains, 
to meet their needs. For centuries people have been settling on the banks 
of the country's rivers, streams, and oceans, taking advantage of the water 

supply, transportation, energy source, wildlife habitat, and other benefits floodplains 
provide. Unfortunately, human development on floodplains usually 
results in flood damages. In the United States the result of this widespread 
damage was a second wave of activity, during which individuals and governments 
enthusiastically engaged in the construction of dams and reservoirs, 
levees, floodwalls, and stream channelization projects in efforts to prevent 
or limit damages to development that was either knowingly or inadvertently 
placed within the floodplain. Thousands of water supply projects, particularly 
in the arid West, dramatically changed the natural resources of riparian areas. 
Millions of acres of inland and tidal wetlands were filled or drained, causing 
loss of natural flood storage areas, a lowered capacity for filtration of pollutants 
and groundwater recharge, and reduction or elimination of some 
wildlife species. 

By the late 1970s it was estimated that from 3.5 to 5.5 million acres of 
floodplain land had been developed for urban use, including more than 6,000 
communities with populations of 2,500 or more. Annual growth in these 
floodplain areas was between 1.5% and 2.5% during the 1970s, roughly twice 
that of the country as a whole. The coastlines of the United States have been 
attracting people and their accompanying property and infrastructure in ever-
increasing numbers for several decades. The 1980 U.S. Census units within 
50 miles of the Atlantic and Gulf coastlines increased in population from 34.1 
million in 1940 to 63.3 million in 1980-an increase of 85%, compared with 
70% for the nation as a whole. The population of Gulf Coast counties 
increased by 200%. 

In 1991 the floodplain lands in 17,466 examined communities occupied a 
total of 146,600 square miles (93.8 million acres), including about 9.6 million 


households and $390 billion in property. Florida was the state with the highest
composite risk, followed by California, Texas, Louisiana, and NewJersey.


This large-scale development and modification of riverine and coastal
floodplains has resulted in a major increase in the land area of the United
States that may be economically developed and used, but at a high price
extracted annually in deaths, personal injury and suffering, economic loss,


and damage to or destruction of natural and cultural resources. There are two
main kinds of floodplain losses: loss of life and property, and loss of natural
and cultural resources. Both types continue to occur even with increased aware-
ness of the value of floodplains and of the risks of floodplain occupancy. The
actual and relative amounts of these lossesare not well quantified.


It has been estimatedthat 3.5 to 5.5 million acresof floodptain land hawlbeen developedfo urban use by 
, 
the late 1970s. In many cases, this change has resultedin greatly altered river corridors and adjacentlands. 

Channelmodification,SiouxCity, Iowa. I 

Average Annual Flood Damages for Five-Year Periods
in the U.S., 1916-85


-

5500 

5000 

Althoughthereis no untformmeasureofflood losses, 
flooding clearlyconstitutes the most pervasive and costly4500 -Damages hazardfacingthe nation. From1965 to 1.98.9,totalassistancepaymentsfor 
Presidentiallydeclareddisasters 
4000 * Damages (1985$) amountedto almost$6.8 billion. Of that, $5.2 billion 
was allocatedforflood-and hurricane-related

damage.

e 

.5 3500 / Damages/200 million population Flooding,Prairiedu Chien,Wisconsin,1975. 

a 

3000-(1985$)

0Co 
0 2500 7

C 

a 2000 

0 

I 

1 r- f /I

IDUU


1000 


500 


1920 25 30 35 40 45 50 55 60 65 70 75 80 85 

Last Year of Five-Year Period 

Source:National Weathcr Serviei 


17 


Although less dramatic than urban or coastal flooding, 
rural flooding and consequent agriculturallosses account 
for almost 50% offlood damages in the United States. 

Flooding along the Snohomish River, Washington State, 
November 1986, 

Damages to infrastructure for as much as 

may account 
25 %o of the total damages incurredduring flooding


Bridgedamaged by flooding, Jefferson Island, Louisiana, 

1.979. 

In a 1971 study, the Corps found that approximately 
24% of the nation's shoreline was significantly eroding. 
Iwo-thirdsof this land was privatey owned. 

Duneerosionand house collapse, Sandwich, Mas-
sachusets.


I 

Loss of Life and Property 

Between 1916 and 1985 there were, on average, 101 flood-related deaths 
annually; there is no indication that deaths are increasing or decreasing on a 
per capita basis. On the other hand, there definitely was an increase in flood 
damages over that 70-year period. Per capita flood damages were almost 2.5 
times as great from 1951 to 1985 as from 1916 through 1950, after adjusting 
for inflation. Property losses from floods appear to have been fairly constant 
in relation to the overall national economy. For example, flood losses in 1937 
in the Ohio and lower Mississippi River basins ($440 million) amounted to 

.0049% of the GNP for that year. Flood damages in 1983 ($4 billion) 
amounted to only .0012% of GNP. Consistent, reliable data on historic flood 
deaths and damages are still not being collected. Information on the financial 

aid given by many federal and state agencies is not available in a form that 
separates flood-related damages from other types of natural and technological 
disasters. Nevertheless, there are numerous figures available to help establish 
the type and extent of damages suffered. 

* Floods account for more losses than any other natural disaster in the 
United States (with the exception of drought losses during certain years 
or long-term periods). In most years flood damages constitute the bulk 
of federal financial aid for disasters. 
* From 1981 to 1985, about 23% of all Presidentially declared disasters 
involved coastal flooding, and about 49% of federal disaster aid obligations 
were attributable to coastal damage. 
* A total of $2.6 billion in flood insurance claims were paid out by the 
National Flood Insurance Program from 1978 to 1987. Over 31% were 
for flooding in areas outside the 100-year floodplain-the result of 
rapid urbanization that exceeds the capacity of managers to remap and 
regulate, or to manage stormwater. 
* The Federal Highway Administration provided $442.3 million in emergency 
relief from 1986 through 1989. 
* About half of the nation's annual flood damages are agricultural losses. 
* The Small Business Administration issued $78.7 million in economic 
injury disaster loans and $67.9 million in physical disaster loans in 
fiscal year 1989. 
* On irrigated cropland, flooding can damage irrigation facilities, such 
as ditches, pipelines, and sprinklers. Sediment deposited by flood 
waters can reduce long-term yield by covering fertile land with infertile 
deposits and can damage existing crops by interfering with their 
growth. These losses range from $150 to $500 million annually. 
* A review of eight disasters from the 1950s and 1960s found that 
damages to infrastructure accounted for about 25% of the total 
damages. Other estimates put that figure at 10-19%. 
* Over three-fourths of all Presidentially declared disasters involve flash 
flooding; flash floods have been the cause of most weather-related deaths 
in the United States. 
* A study of streambank erosion estimated $295 million in average 
annual damages. Neither the damages from nor costs of coastal erosion 
have been estimated. 
* Total national losses from lake level fluctuations exceeded $250 million 
from 1981-1986. 
* The overall damages and cleanup costs from the 1980 eruption of Mt. 
St. Helens, which caused catastrophic flooding and mudflows, were 
estimated at $1.2 billion; over $875 million was needed to restore land, 
clean up rivers, and provide flood protection to area communities. 
* Three tsunamis have resulted in losses in recent times: 173 deaths in 
Hawaii in 1946; 61 deaths in Hawaii in 1960; and 107 deaths in Alaska, 
4 in Oregon, and 11 in California in 1964, plus $100 million damage 
on the West Coast. 

Streambank Erosion 
Average Annual Damages in $ Thousands 

P c-Northet So~ris-RerA"--NewEngin./ ,600 1,200 1800 

L |periasissaii J ,7OO 
70atLaos-a 

Basin',

( Great Missouri Basin

\500 / : 16,t00. ' : 

aCalior*a -hio VaI0,56,200 iColoroo Basin !.iddle Atlantic 
j4,800 -t [ 0 I ,n 10 900 

Arkanas-White-FRd ,

~1

3,500 

Rio Grande LowerMississippi 

W~OO ~ 38,900--

LAXlaska 4 rTexas Gulf -,-FIR South AthnticGulf 
1,200 780' 8~ 

Hawaii 

0 

U.S. Total= $294,600,000 
Source.U.S. Army Corps of Engineers 

Loss of Natural and Cultural Resources 

All three types of floodplain resources-water, living, and cultural-are 

threatened by human use of the floodplain, whether for urban development or 

seeminglybenign agriculture or forestry. Furthermore, because floodplains are 
integrated natural systems, tampering with any one of the component natural 
processes may often lead to trouble. Increased runoff resulting from wide


spread clearing of vegetation, destruction of wetlands, dune removal, paving, 
roofing, and other activities can increase flood peaks, stream erosion, and 
sediment transfer. Blocking runoff or interrupting the movement of groundwater 
can raise flood profiles, increase pollution, and interfere with groundwater 
balances and the distribution of sediment. Fertilizers, septic systems, 
chemical and petroleum spills, and leached materials from waste disposal 
areas can degrade the surface and groundwater resources of floodplains. 
Recreational and commercial river traffic often seriously contributes to stream-
bank erosion. Increased sediment can bury food sources and spawning areas 
and pollution can poison plants, animals, and other living things. Develop


ment can remove shelter and food, and prevent fish and other wildlife from 
moving through their habitat. Erosion of coastal wetlands and filling of wetlands 
destroys habitat. In many cases, developed floodplains do not have the 
aesthetic and recreational attributes of natural ones. Improper agricultural 

and forestry practices can be just as destructive of natural floodplain values 
as poorly planned urban development. 

The nature of the value of natural floodplains makes the damage to them 
difficult to quantify, but the losses have been assessed even if no economic 
value has been assigned. 

* Over 90% of the United States' coastal barriers are subject to flooding 
and erosion because of their seaward exposure, inherent instability, and 

relatively low-lying topography. In spite of these risks, 14% of the area 

of coastal barriers is urbanized (compared to only 3% of the entire 

mainland), including Atlantic City, Ocean City, Virginia Beach, and 
Miami. This development also interferes with the natural ability of the 
barriers to absorb storm energies, thereby reducing protection for 
mainland populations and development as well. 

7he Corpsestimatesthat in the UnitedStatesthereare 
574,500 miles of streambank witherosionproblems142,100 
with seriousproblems.About78% of all stream 
bankerosiontakesplacewestof the mainstem qfthe 
MississippiRiver. 

Humanoccupation and use of a floodplain threatens its 
naturalresourcesin many ways. Signficantamongthese 
is the potential for increased

pollutiondueto improper 
waste disposal, spills, and various formsof nonpoint 
source pollution. 


just as urban developmentof floodplains mustbe carefully 
planned, the effects of agricultural and forestry uses must 

also be analyzed and understood before changes in a floodplainare 
male. 

ConnecticutRiver nearDeerfield,Massachusetts. 

Overthe years, theconversionof wetlandsto other useshas 
resultedin more than half f/ all U S. wetlands being lost. 

DredgingnearAmelia, Louisiana. 

Developmentin a floodplain may 1) increase runoff 2) block runoff and interrupt groundwatermnovement, 
and 3) increasepollution. It can affect living resources and habitat in numerous, sometimes unpredictable, 
wvays. 

Developmeznt

in coastal marshland of/Louisiana 

* Human activities have already profoundly affected floodplains and the 
nature of flooding throughout the arid and semi-arid Southwest, where 
rapid development is expected to continue. Many changes that began 
450 years ago with the introduction of cattle are still affecting the basic 
hydrologic cycleand geomorphology of the region. Plant and animal 
associations that evolved for 10,000 years have been irreversibly altered, 
and the effects of this are still only vaguely understood and generally 
unmanaged. 
* About 54% of the original 215million acres of wetlands in the nation 
have been lost since European settlement. A recent U.S. Fish and 
Wildlife Service study estimates that there are about 100 million acres, 
or about 5% of the land mass, left in the continental United States, 
and the U.S. Office of Technology Assessment estimates that there are 
about 200 million acres, or about 60%, in Alaska. Historically, the 
greatest portion of this loss by far was the result of draining wetlands 
Original and Remaining Acreages 
of Wetlands in the Lower 48 States 

Lost (54%) 

Remaining (46%) 

Source:Fish antdWildlife Service, U.S. Department of the Interior 


for conversion to agriculture. Major areas of bottomland hardwood 
forests have been cleared, drained, or converted to agriculture. Agricultural 
uses were estimated to account for 54% of the 300,000 acres lost 
annually from the mid-1970s to the mid-1980s. 

* Riparian ecosystemsare being degraded and destroyed throughout the 
United States. The lower 48 states originally contained 75-100 million 
acres of indigenous, woody riparian habitat, but today only 35 million 
remain in nearly natural condition. The rest have been inundated by 
reservoirs, channelized, dammed, riprapped, converted to agricultural 
use, overgrazed, paved, or altered by a combination of factors that have 
impeded their ability to stabilize and maintain the biological diversity 
of their own watersheds. Riparian habitats have been lost in every 
region of the country. 
* Channelization and other flood control projects can destroy riparian 
habitat by clearing vegetation; eliminating sandbars, islands, and productive 
backwater areas; and accelerating bank erosion. Between 1940 
and 1971the U.S. Army Corps of Engineers assisted in navigation and 

flood control projects to alter 11,000 miles of streams. The Soil Conservation 
Service has installed 10,700 miles of channel modifications. 

* Dams can alter riparian habitat in many ways, such as drowning it 
under reservoirs, desiccating it by downstream dewatering, or rendering 
it non-regenerative by interrupting the natural flood cycle. The 
nation's 68,153nonfederal dams have altered or destroyed tens or hundreds 
of thousands of miles of riparian habitat. Impoundments by the 
federal government have transformed major river systems, including 
the Columbia, Colorado, Missouri, and Tennessee, into a series of 
artificial lakes, severely decreasing the diversity of habitats available 
to wildlife but creating other habitats and environments. 
* By overgrazing, trampling vegetation, compacting the soil, and breaking 
down streambanks, livestock have seriously damaged watersheds 
and riparian zones. These impacts have led to increased soil erosion, 
higher nutrient load in streams, bank erosion, and lowering of water 
tables. Inadequate livestock management has been responsible for the 
serious lack of riparian habitat regeneration on federal rangelands in 
the West. 

* Lowering of the water table in arid and semi-arid regions causes a 
drastic and often permanent degradation of the floodplain. In many 
areas, a high water table and accompanying pools and springs are the 
only sources of moisture for riparian vegetation and native animals. 
Introduction of non-native plants has also significantlycontributed 
to alteration of floodplain habitat. Salt cedar, for example, which was 
imported to North America during the 19th century, has become the 
predominant riparian tree specieson the lowerColorado, the lower Rio 
Grande, and Pecos rivers. It covers some 500 square miles in those basins 
alone, and makes the riparian areas less suitable to many native birds. 

Alterationis widely usedto controlfloodingby increasing 
the carrying capacityof a stream channel.7echniquesinclude 
straightening,deepening, widening, or paving the 

channel;removingdebris;raisingor enlarging bridgesand 
culverts,removingdams and other obstructions; and installingundergroundconduits.
However,unlesscarefully 
plannedand executed,suchchannel modification can significantlyaffectriparian 
habitat. 

Artificialchannel(buriedconduit) under construction,
LaPlace,Louisiana.


The introductionof cattle tothe American Westhashada 
fundamentaleffecton thenationslandscape-inparticular,
on riparian landsin semi-arid environments.In many 
casestheresult has beensoil compaction, loss of vegetation, 
increasederosion,and the consequent deteriorationof 

floodplains,riverbanks,and river waterquality. 


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In the laoer part of this century, the scope of floodplain 
managementbroadenedto encompass a wide range of techniques. 
The "Point Area" of Pittsburgh, Pennsylvania,at 
theconfluenceof the Allegheny and MonongahelaRivers, 
demonstratesthese advances. For example, the transportation 
corridor in theforegroundhas been replaced by an 
openspace park, highways have been elevated, and prominent 
structures havebeen floodproofed. These physical 
changes,along with a comprehensive 

system of upstream 
flood control, land use controls, and a coordinated

flood 
warning and preparedness

program,have significantly 
reducedtheflood hazard in downtown Pittsburgh. 

Above: Pittsburgh, Pennsylvania,Point Area 1948. 
Below: Pittsburgh, Pennsylvania,Point Area 1982. 

Previouspage: Davis Dam, Colorado River, near BullheadCity, 
Arizona. 

The History of Floodplain Management 

Before 1965, government action to reduce floodplain losses was primarily a 
response to significant loss of life or property damage. Most of these efforts 
sought to control flooding through structural measures. During the mid-1960s, 
federal policy began to broaden to include nonstructural means. The last 25 
years have witnessed a major expansion in floodplain management, incorporating 
better ways for analyzing and predicting flooding, paying appropriate 
attention to the natural resources of floodplains, and adjusting the roles of 
federal, state, and local governments and the private sector. 

1900-1960: The Structural, Federal Era 

During the 1800s and early 1900s, flood control efforts were undertaken 
by levee districts, conservancy districts, other local and quasi-public groups, 
and individual landowners. Federal involvement was sporadic and concerned 
mainly with flood impacts on navigation, forestry, or agriculture. After the Civil 
War, Congress authorized federal agencies to begin stream gaging as a start 
toward flood forecasting and warning, but federal involvement still was limited. 

After two decades of major flooding along the Mississippi, Ohio, 
Potomac, Susquehanna, and various New England rivers, Congress committed 
the federal government to flood control of all navigable rivers in the 
nation in the Flood Control Acts of 1917, 1928, 1936, and 1938. The combined 
effect of these acts was the federal government's assumption of the full 
cost of building and maintaining reservoirs and channel modifications, and 
the placement of most of the responsibility for efforts to control floods in the 
hands of the Corps. These laws did mention other measures for reducing 
flood damages, such as evacuation, watershed improvement, and reconciliation 
of needs of upstream and downstream users, but the emphasis was on 
controlling flooding with such structures as dams, levees, and channel 
modifications. 

Twenty-fiveyears later the Corps' authorized flood control program 
encompassed 220 reservoirs (90 million acre feet of flood control capacity), 
over 9,000 miles of levees and floodwalls, and 7,400 miles of channel modifications-
a total of 900 projects with an estimated federal cost of $9 billion. 
Other federal agencies also became involved in flood control. The Tennessee 
Valley Authority's regional program of resource development included construction 
of dams and reservoirs for flood control and other purposes. The 
Bureau of Reclamation and the U.S. Department of Agriculture began 
including flood control with other project considerations. During the 19301950 
period the U.S. Forest Service established research watersheds to study 
water yield and timing of flows from forest and range watersheds. The 
Coweeta Hydrologic Laboratory in North Carolina was established in 1934 
as the first of these watersheds. The Soil Conservation Service began helping 
individual landowners in 2,600 soil conservation districts to use conservation 
measures, including flood prevention. 

Along with federal involvement in flood control came federal relief for 
flood victims. The Federal Disaster Act of 1950 was the nation's first comprehensive 
disaster relief act, and Small Business Administration disaster relief 
programs were also begun in the 1950s. 

Before the 1960s a number of single-purpose federal laws and programs 
protected various specificnatural resources and thus indirectly helped protect 
the natural resources of some floodplains. For example, the creation of 
national parks and federal forest reserves resulted in the protection of significant 
areas of natural floodplains. Other laws protected wildlifehabitat and 
preserved open space for conservation and recreation, thus ensuring that 
some floodplain areas would be left in their natural states. 

1960s: A Time of Change 

Despite the billions of dollars in federal investments in structural 
projects, and the demonstrated effectiveness of these measures, flood losses 
and disaster relief costs continued to rise because of unwise occupancy and 
use of the nation's floodplains. Thus, broader approaches were studied and 


applied, including zoning and other land use regulation, flood forecasting, 
federal flood insurance, relocation of property, and alternative water storage 
techniques. Major steps were taken to redefine federal policy. Section 206 
of the Flood Control Act of 1960authorized the Corps to provide technical 
services and planning assistance to communities for wise use of the floodplain 
and for ameliorating the flood hazard. The Corps began producing maps and 
floodplain information reports describing a community's flood hazard from 
a broader perspective. The President's water policy statement of 1962 established 
policies and procedures for comprehensive river basin plans. The Water 
Resources Planning Act of 1965 created the U.S. Water Resources Council 
and authorized federal-state river basin commissions for comprehensive 
basin planning. 

House Document 465, the report of a Bureau of the Budget Task Force 
on Federal Flood Control Policy, advocated a broader perspective on flood 
control within the context of floodplain development and use. Executive Order 
11296, Flood Hazard Evaluation, directed all federal agencies to evaluate the 
flood hazard before undertaking federally financed or supported actions and 

to play a lead role in preventing uneconomic use and development of floodplains. 
Fifteen states, most notably Wisconsin and Minnesota, adopted floodplain 
management programs, some of them providing for strict regulation. 
Local governments also began trying to deal with the hazard in a more comprehensive 
way, usually with assistance from a state or federal agency such as 
the Tennessee Valley Authority. 

HISTORY OF 
A UN4IFIEDNATINAL PROGAM FO FLOODPLAINMANAGEMENT 

oueDocmn 6, aigFodos s Congress

AWwMv a sbittdto byPresdetLyndon 

it August 196. It had Ikk 
indnyattemptlto slow the mounting national toof flood losses, uchke by over $7 billion in national investments 
in flood cotrol pr~ectasince os mDouent 465 recognized the need for a unified approachndon 

_ohnson een prepardbt Focon Flood Control olic the administratis request 

1936. e 
lanningesu or feral agy actiontob i ta ofaprograninldn 
ne eilton pcfcsudeadnwprogram forcollectinganddissemntgfloreadinfomton 

A Uifid NtionaProooa, 1976 
In espns 968Bueauoftoa heBudetreqes fo areport pursuan to adirective in Sction 32cOfteNtoaFloadtoa175US.GneaIsrac At AcunigOfe eor riiiznG ousDount45 andEhecu-
tieOre 126,te .. WterReoure oni umte to the Preidnt theUnfliNtioml)%whjr lodpliiA~~mn97. i id cagereletd sgifcatrecognition thatmretanfoo ose

hs evsin wos 
wee nvlvdesabiseda more detiled frameworkfor thepoga, desi~ the gretl cagda cnexynshc 
it _udbemplemented(numerouschangesin flood-relatedfedal progrshaditken place),and added managemtstraegiesandtoolsford 
sate anloaouse. Therep ontne rim 
'weakest ofurrmnenteffot. f

component " 

Atouhhe7UifidaonaPoammadasinificnard in d management, its very 

efecivness adeitqicrated. Serleeutielvl aciosPrsidntCarersfodpanmanaent policyartclte in17,EeuieOdr 18 n 1t199,andte Preidn' 1978watr p lc nititie-wereson0 

taemaigth 96 vrionoslet. TheFedralIntragnyFlopain MangeentTak Foc udten 
refiaPIm i reprubmittedby the Water Resources Council to the Presidtn 1979 
Tsreiinicroae ealoncern with the "natural and beneficial values" offooas, res t 
Prsdn':oiydietvsaddthe strategies (addin two: restoration if naturalvs:adp 
natualvlstetu amewoir a ly and emphasized the insufficient awaren tera 
tives eto"lakofautechniclandpro informationto guidef0loplaindecisionmkr. 

In:1982,theOceof Managemnt andthudge ned r sibty for theiie t to the 
chairof task Fr The 'iThkFboe submitted 
anupdatedUnifiedNatioal in 1986,nng thAthe1979 reporthd ted by the relative 

successandchangesinfalprogramsand capability at the state

by the strengtheningoffloodplainmanagementand loaees"Teecagsicue the use of federal initerageny haadmtiainteams, passage fte 1982 

CoastalBarerResocesActrstrictingfeale

resth ightenourae delop ofcal barriers

alontheAtlntiandGulfco

ftwom dom SienceFountnstudies

ional: on flaz 

ar iiainh reportincuemorexplctrcmedtosfrtefdrlrl nspotn tt oa 

inita tives, W0g:00g:f:0:::00f0?:0~::000:000:00:f:V:0:XVff :D::0:~::0:00:::::00::000:ffX:??0t~f:00:00F0:X00 000X 


Coastal managementin the United States is shaped by the 
federalCoastal Zone Management Act of 1972 and the 

CoastalBarrier Actof 1982. Theformer 

Resources author-
ized federal grants to states for development and implemen tation 
of coastal managementprograms for water and land 
resources in coastal zones. As amended, the Act incor- 
porates bothfloodlossreduction and protection of natural 
resourcesinto program goals. The latter legislation estab-
lisheda system of largelyundeveloped

coastalbarriers 
along the Atlantic and Gulf coasts in which federally sub-
sidized development is restricted. 

Sand dunes, Santa Rosa Island. Florida. 

Two major pieces of legislation rounded out the change in federal policy. 

In 1969 the National Environmental Policy Act provided for consideration of 
environmental values in all federal and federally supported actions, making 
it possible to recognize the multiple values of floodplains. The National Flood 
Insurance Act of 1968 made federally subsidized flood insurance available to 
participating communities, contingent upon their implementing nonstructural 
flood loss reduction measures embodied in local floodplain management 
regulations. 

1970s: The Environmental Decade 

During the 1970s numerous state and federal environmental laws and 
programs and water resources initiatives began to decentralize water management 
and bring about a much broader perspective on floodplains. Numerous 
federal programs took shape for water quality management, pollution and 
erosion control, watershed management, and protection of groundwater, 
aquifers, inland and coastal wetlands, barrier islands, and specific habitats. 
Complementary legislation was passed by many states, requiring environmental 
quality review and impact assessments at state and local levels. 

During this decade, changes were made in the National Flood Insurance 
Program; a proposal for a Unified National Program for Floodplain Management 
was issued and later updated; and executive orders on floodplain management 
and protection of wetlands were issued, making disaster relief contingent 
upon mitigation action and requiring the consideration of nonstructural 
measures in federal flood control projects. 

State and local involvement in floodplain management increased with the 
appointment of National Flood Insurance Program coordinators in all states, 
the adoption by more states of regulatory programs, increases in state budgets 
for floodplain management, and the adoption of resource conservation legislation. 
About 17,000 communities adopted floodplain management regulations, 
and many adopted regulations to manage other local resources, such as wetlands 
and coastal areas. 

1980s: Continuing Evolution 

More attention was given to implementing policies and programs for 
managing floodplains during the 1980s. The federal government took the role 
of coordinator and provider of technical assistance, while state and local governments 
gradually fashioned floodplain management strategies appropriate 
to their own jurisdictions. Interagency agreements were crafted to establish 
common policy on nonstructural measures and to evaluate floodplain management 
options after disasters. The Coastal Barrier Resources Act of 1982 established 
a policy of nondevelopment and avoidance of high hazard areas by prohibiting 
new federal expenditures on certain undeveloped coastal barriers. 

The natural and cultural resources of floodplains received more protec


tion through multipurpose, often federally supported projects for open space, 
recreation, urban renewal, greenbelt, and waterfront redevelopment. 
State and local officials became even more involved in hazard mitigation 
planning with the implementation of requirements for planning after all 

Presidentially declared disasters and with participation in interagency hazard 

mitigation teams. 

The Management Framework 

Like any activity, floodplain management is carried out within a structure 
of legislative, administrative, economic, and judicial opportunities and con


straints. The way in which floodplain lands and waters are handled, decisions 
are made and actions taken-whether by the U.S. Congress or by a single 
homeowner in a floodprone area-depends upon the relevant law, the policies 
and programs of government agencies, funding, public interest and opinion, 
and the availability of needed information. The framework for floodplain 
management has been strengthened significantly since the 1960s. Before then, 
flood loss reduction was largely dependent upon flood control works and fed


eral actions; at the same time, a number of single-purpose federal laws and 
programs protected various natural resources, only indirectly addressing pro



27



GENERAL PRINCIPLES FOR
FLOODPLAIN MANAGEMENT


* The federal government has a fundamental interest 
in how the nation's floodplains are managed, but the 
basic responsibility for regulating floodplains lies 
with the state and local governments. 
* Floodplains must be considered in the context of 
total community, regional, and national planning 
and management. 
* Flood loss reduction should be viewed in the larger 
context of floodplain management, rather than as an 
objective in itself 
* Sound floodplain management embodies several 
aspects. 
* goals (wise use, conservation, and development
of resources);
* objectives (economic efficiency, environmental
quality, and social well-being);


* considerationoffuture needs and the role of the
floodplain;
* evaluation of alternative strategies for alleviat-
ingflood losses;
* accountingfor benefits and costs and inter-
related impacts offloodplain management
actions;
* motivation of decisionrmakers;
* coordinationof agencies at all levels for all
aspects of floodplain management; and
* evaluation through continuous monitoring and
reporting to the public.
Source. A Unified National Program for Floodplain 
Management, 1976 

tection of the natural and cultural resources of floodplain. Today's floodplain 
management framework is a product of planned initiatives, evolved methods, 
and fortuitous circumstances. Many aspects of the framework developed 
independently and then were incorporated for the common purpose. Many 
were intended at the outset to complement each other. Many apply to floodplains 
only incidentally but nevertheless serve an important function. 

The idea of a unified national program for reducing flood losses was 
first set out in House Document 465 and has been refined and expanded 
since to produce A UnmfiedNationalProgram for Floodplain Management.It establishes 
as a basic national goal the wise use of floodplains; sets forth the conceptual 
framework of a multiobjective approach to use of the nation's floodplains, 
including flood loss reduction and natural values protection; identifies 
implementing strategies and tools; and recognizes the respective roles of each 
level of government and the private sector in the decisionmaking process. 

There are four main strategies for reducing floodplain losses. They are 
described in detail in the Unified National Program documents. Each strategy 
can be carried out by using one or more specified "tools"-activities undertaken 
by governments, individuals, or the private sector that have an impact 
on floodplain management: 

* Modify susceptibility to flood damage and disruption. 
* Modify flooding. 
* Modify the impact of flooding on individuals and the community. 
* Restore and preserve the natural and cultural resources of floodplains. 
At all levels of government and within the private sector, the tools and 
strategies for floodplain management take various forms, including components 
of broader initiatives, legislation, and policy directives in water resources 
management, emergency management, environmental protection, and projects 
for community development and redevelopment. Federal, state, and local 
programs and private efforts to manage the natural and cultural resources of 
floodplains are usually focused on the particular resource or activity that happens 
to occur on the floodplain rather than on the floodplain itself. 

The Federal Government 

At the federal level, flood loss reduction is accomplished through a 
network of laws, executive orders and directives, administrative regulations, 
interagency actions, and agency policies and programs. These components 
of the framework address various aspects of floodplain management, including 
insurance, land use, disaster preparedness and relief, information and 
education, warning systems, and structural flood control. At least 25 subdivisions 
of 12 departments and agencies have significant responsibility for some 
aspect of floodplain management. 

The water resources values of floodplains are managed through programs 
for water quality, pollution control, watershed management, erosion 
control, and groundwater and aquifer protection. Restoration and preservation 
of the living resources of floodplains have been addressed in multiobjective 
federal programs or activities aimed at protecting inland or coastal wetlands 
or barrier islands. Other federal programs have been specifically 
directed at protecting habitat. Cultural resources have been protected through 
a variety of federally supported programs for open space, recreation, urban 
renewal, waterfront redevelopment, and historic preservation. 

State Government 

State activities for floodplain management have responded to and often 
paralleled federal activities. States administer locally adopted and enforced 
floodplain management regulations pursuant to the National Flood Insurance 
Program. All coastal states have some type of permitting program for development 
activities below mean high water and most coastal and Great Lakes 
states have federally approved coastal management programs. Every state has 
a multihazard emergency operations plan that covers floods. All coastal states 
and some inland states have wetland protection programs of some sort which 
include mapping, permitting, and protection. 


I

SOME COMPONENTS OF THE FEDERAL 
FRAMEWORK FOR FLOODPLAIN MANAGEMENT 

The Clean Wtter Act of 1972 * Coastal Barrier ResourcesAct (1982)* Coastal Zone Management Actof 1972* The
DamnSafety Act (1986)* The Disaster ReliefAct of 1974 * The Disaster Relief and Emergency Assistance Amend-
ments of 1988* The Emergency Wetlands Resources Actof 1986* The Endangered Species Actof 1973^ Executive


Order 12127 (0979) 0 Executive Order 12148 (1977) * Executive Order 11296 (1966) * Executive Order 11988 (1977)

*Executive Order 11990,Protection of Wetlands * The Federal Crop InsuranceAct (1980)* The Federal Insecticide
Fungidi, and"Rodenticide Act * Federal Interagency Floodplain Management Task Forceestablished 1975*0The
FWeeralLand Policyand Management Actof 1976 * Fish and Wildlife Coordination Actof 1958* The Flood Disaster


Protecion Art of 1973 * The FoodSecurity Act of 1985* House Document 465, A Undtioal Pogian in;
FW Cloos*


The Housing Actof 1961* The Housing and Urban DevelopmentActof 1969 * The Housingand Corn-
munt Development Actof 1977* The Housing and Community Development Act of 1987*0 The Land and Water


QConseion Fund Act(96) * The National Darn Inspection Actof 1972* The National Erivironmenil Poly Act
(199 *The National Flood Insurance Act(1968)* The National Forest Management Act of 1976* The National
Histori PreservationAct (1966)* The North American WaterfowlManagement Plan (1986)* 0OMB Mernorandunm,
"Nonstrucural Flood Protection Measures and Flood Disaster Recovery"(1980) * The Omnibus Budget Reconcili-


ationact of 98101 The ReservoirSalvage Act of 1960 * The Safe Drinking Water Actof 1974* The Soil and Water
Resc Consevation Act of 1977* lTheTax Reform Act of 1986 * United States-Mexico Boundary Treatyof Novem-
ber23, 19700 The Water Bank Act (1970)* Water PollutionControl Act Amendments of 1972 * The Water QualyW
Act of 1987a The Water ResourcesDevelopment Actof 1974 * The Water ResourcesDevelopment Actof 1986* The
Water ResourcesDevelopment Act of 1990 * Water Resources Planning Act of 1965 * The Watershed Protection and
FoodPrevention Act of 1954 * The Wild and Scenic Rivers Act of 19680'flood Control Act of 1917 0 Rivers and
Haors Act of 1930 a Flood Control Act of 1936


Several states have adopted their own statewide floodplain management 

regulations, and in some states executive orders compel state agencies to con-
sider flood hazards before carrying out their activities. Several states have
adopted environmental policy acts that require analysis of the impacts of


proposed state and local actions on natural resources, including those of the 

floodplain. Every state has an agency involved in planning, funding, or spon-
soring structural flood control projects. Floodplain management is further
accomplished through state-levelregulatory and nonregulatory programs
directed at wetlands, dune protection, restoration and protection of living
resources and natural areas, mapping, flood conveyance and storage, dam
safety, pollution control, natural crops, groundwater supply, wildlife habitat,


historic preservation, recreation, and shoreline management. THE IDNDR 

Local Government In 1987 the United Nations GeneralAssemblydeclared1990 to 2000 AD as the International

The adoption and enforcement of local floodplain regulations is now 
widespread because of the National Flood Insurance Program. Many local 
I)Deade-forNatural DisasterReduction (IDNDR). 

It is anticipatedthtatthis assessmentwill providezoning and subdivision regulations protect the natural and cultural resources itseful inputtothe UnitedStatesprogramfor 

of floodplainsthrough shoreline setbacks, density limits, historic preservation theDecade-
guidelines, or specification of compatible uses. Local governments are almost 
exclusivelyresponsible for local drainage and stormwater management. Many 

localities participate as cosponsors of structural projects, providing a small 
financial contribution to the cost of the works. Some localities have coastal 
management programs within a state framework, and some states provide for 
local application of state controls, usually established under legislation gearedtoward multiple goals like protection of wildlifeand sensitive shoreland areas, 
or erosion control. Some communities have developed multihazard emergencypreparedness or operations plans. 

Regional Entities 

Regional entities can be extremely effective in managing floodplains, 
whose boundaries typically do not conform to traditional governmentaljurisdictions. 
Special districts are the most numerous and fastest-growingtype of 

governmental entity in the country; nearly one-quarter of them have natural 

resource functions-soil and water conservation, drainage and flood control, 
and sewerage. The nation's 3,000 counties also have floodplain management 
functions, including storm drainage, land acquisition, flash flood warning, 
emergency response, land use planning, and building regulation (usually of 

unincorporated areas). Nearly 3,000 conservation districts exist, coveringmore 


M 

SELECTED PROFESSIONAL AND
NONPROFIT ORGANIZATIONS ACTIVE
IN FLOODPLAIN MANAGEMENT


American Institute of Architects 
American Land Resource Association 
American Littoral Society 
American Planning Association 
American Rivers Conservation Council 
American Society of Civil Engineers 
American Water Resources Association 
Association of Conservation Engineers 
Association of State Dam Safety Officials 
Association of State Floodplain Managers 
Association of State River Managers 
Association of State Wetland Managers 

The Coastal Society 
Coastal Conservation Association 
Coastal States Organization 
Connecticut River Watershed Council 
The Conservation Foundation 
Conservation Law Foundation of New England 
Council of State Governments 

Environmental Defense Fund 

The Environmental Law Institute 
Environmental Policy Institute 
Freshwater Foundation 
Friends of the Earth 
Friends of the River 
Land Trust Alliance 
League of Conservation Voters 
National Association of Conservation Districts 
National Association of Counties 
National Association of Home Builders 
National Association of State Recreation Planners 
National Association of Urban Flood Manage


ment Agencies 
National Audubon Society 
National Center for Urban Environmental 

Studies 
National Emergency Management Association 
National Fish and Wildlife Foundation 
National League of Cities 
National Organization for River Sports 
National Recreation and Parks Association 
National Trails Coalition 
National Trust for Historic Preservation 
National Water Resources Association 
National Waterways Con ference 
National Wetlands Technical Council 
National Wildlife Federation 
The Natural Areas Association 
Natural Resources Defense Council 
New England Natural Resources Center 
North American Lake Management Society 
The Oceanic Society 
The River Conservation Fund 
Save the Dunes Council 
Sierra Club 
Society for Range Management 

Soil and Water Conservation Society 
The Sounds Conservancy 
The Trust for Public Land 
Urban Land Institute 
Wetlandsfor Wildlife 

The Wilderness Society 
Wildlife Management Institute 

than 97% of the country. They provide planning and technical assistance to 
individual landowners for controlling soil erosion and water pollution, and 
they implement swampbuster, wetland restoration, and erosion reduction 
portions of the Food, Agricultural, Conservation, and Trade Act of 1990. 

The Private Sector 

Besidesundertaking basic and applied research on floodplain management, 
academic institutions also provide education in the field, although so 
far no university offers a program of study specializing in floodplain management. 
Many states have Water Resources Research Institutes, as authorized 
by the Water Resources Act of 1964. 

Over 700 national and local land trusts exist throughout the nation. 
Most are nonprofit organizations that receive land, either through donations 
or purchase, and manage it as open space or for historic purposes. 

There are a large number of professional and nonprofit organizations 
involved in floodplain management. Most are national in scope and accomplish 
their objectives through meetings, publications, lobbying, and fostering 
professional communication. The number of private conservation and watershed 
organizations is even larger. Usually nonprofit with a broad public 
membership, they are typically directly involved in environmental issues with 
flood loss reduction as an indirect goal or benefit. These citizen-based groups 
serve a tremendous public education function, are largely unaffected by partisan 
politics, and can usually respond to an issue more rapidly than government 
agencies. 

Individuals and for-profit corporations have become more involved in 
floodplain management since the 1960s, helping develop floodproofing techniques 
and materials, automated flood warning systems, geographic information 
systems, remote sensing techniques, and computerized information 
management. 

Modifying Susceptibility to
Damages and Disruption


Modifying susceptibility to flood damage and disruption is the floodplain 
management strategy of avoiding dangerous, uneconomic, undesirable, or 
unwise use of the floodplain. The tools used to implement this strategy are 
regulations; development and redevelopment policies; disaster preparedness; 
floodproofing and elevation; and flood forecasting, warning systems, and 
emergency plans. 

Regulations 

Regulations have a potentially greater impact on flood loss reduction 
than any other single floodplain management tool and have been widely used 
over the last 15-20 years. Development that conforms to regulations is less 
prone to flood damage than pre-existing development. 

Regulation is largely a local government responsibility, but throughout 
much of the country there is still widespread resistance to any type of land 
use regulation and concern among jurisdictions that it will be ruled an unconstitutional 
"taking" of private property. Effective enforcement often requires 
more training, personnel, and financial resources than many communities can 
provide. Regulations cannot provide full protection; they have a limited impact 
on existing buildings and infrastructure already subject to flooding, and they do 
not prevent development in floodplains. In addition, most floodplain regulations 
do little to protect the natural resources of floodplains. In fact, to the extent 
that floodplain regulations allow development in floodplains-even though it 
may not be subject to damage-they can contribute to the loss of natural and 
cultural resources. On the other hand, current regulations do provide a de 
facto prohibition on development in wetlands. 


Arizon State Un v riy fi cof H axard Stuzdies is Charliesto n S ui m U iv r t E r h i a e di 


In NO" 

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rid; Lands Studies and Arid Latds Information Cincr * Univcrsity of Califia. Ntioaal Info ;a


S rnt vjce for Earth q uak E agi& i ring *UrnveyfC lf r i , C l fo I Z. i q ak R d c t o P r t 

Chemical Educaotio for Public Unders ES;

nivhynsi

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In stitu til 'ltU 
denter *University of Colorado, U!S w ol ta Ci erfom laioIlgy, ti plSo nd cc D t 

w elixt Progrstm, Disaster PCOP'lardnces n P 

and ! s a iiai ~ 

*UtMvciiit o~ No Ct oa ai Covet A* Urban ap4 ASth 
A~i~ .a a nnin b eg me Prpio W

xi tr ti r d hP m ii 

S o w w: d p c Nr a da c

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ity Un, isasxter Oneg* 0ii C Socia

;t;;,vlU~tI ~ j> E~ttitPops 

t ii ~ ~ t M y . d s t m r 
e s t f P s y v 1 h h r o 

t 

The most widespread floodplain regulations are the minimum requirements 
of the National Flood Insurance Program, which must be enacted and 
enforced by communities participating in the program. The minimum regulations 
vary depending upon the risk studies and mapping that have been done 
in the community, but include 

* permitting for all proposed new development; 
* reviewing subdivision proposals to assure that they will minimize flood 
damage; 
* anchoring and floodproofing structures to be built in known floodprone 
areas; 
* safeguarding new water and sewage systems and utility lines from 
flooding; and 
* enforcing risk zone, base flood elevation, and floodway requirements 
after the flood insurance map for the area becomes effective. 
There are numerous performance and prescribed standards applicable 
to each of the zones on flood insurance maps. The Federal Insurance Administration 
has several programs to help states and communities adopt and comply 
with the regulations. Other federal agencies provide technical and planning 
assistance and support. 

Since the 1960s the number of state and local governments exercising 
regulatory authority over floodplain uses has increased markedly, and the variety 
of regulatory approaches has expanded. A given state may directly regulate 
the flood hazard area, set standards for local application, or regulate the flood 
hazard area as part of a broader resource protection and management program. 
To meet these requirements, local governments adopt specific floodplain 
management or stormwater management ordinances and incorporate 
floodplain management provisions into zoning and subdivision regulations, 
housing and building codes, and resource protection regulations. The number 
of communities with regulatory requirements more stringent than those of the 
National Flood Insurance Program is unknown, but clearly is in the thousands. 

Average Losses per 1,000 Flood
Insurance Policies on Unregulated


, 14 

E~  12E 

versus Regulated Structures, 1978-88 
26 
24-StnructuresBuilt 
22 BefornI Regulation 
8 20 
!: 
, 
E  
18 
16 
-

,60

0i 10 

Ea 

Structures Built 
s8 After Regulation 

4 

2-

U 

0 __ 

Source.FEMA/FIA 

ENFORCING LAND USE 
REGULATIONS IN MAINE 

In 1983 the Maine legislature enacted "Rule80K" 
to allow less expensive andfaster enforcement of local 
land use regulations. Once local code enforcement 
officials are trained, they can take a violation directly 
to the district court without an attorney. Procedures 
are followed that are less fornmal than usual but 
do not sacrifice the defendant 's due process rights. 
The court can levy a fine and order abatement of 
the violation. 


Development and Redevelopment Policies 

THE SOUTH CAROLINA Federal, state, and local governments all have established programs, poli-

BEACHFRONT MANAGEMENT ACT 

cies, and directives to avoid inappropriate development and redevelopment of 

The South Carolina Beachfront Management Act the floodplain. 

establishesa "no construction" zone beginningat the Federal policies relating to the design and location of services and utilities 

crest of the actual or theoretical dune line and extend


(roads, bridges, and sewer lines, etc.) in floodprone areas include the National 

ing landward 20feet or 40 times the average annual 

rateof erosion, whichever is greater. The legislature Environmental Policy Act, Executive Order 11988,and the Coastal Barrier 

anticipated that the Act would result in the gradual Resources Act. All of these either restrict federal participation in development 

eliminationof'structuresbuilt too close to the ocean in floodprone areas or require careful review of the impacts on the floodplain 

and hence subject to damage or destruction from of proposed federal or federally supported activities. 

hurricanesand other coastal storms. Several states have issued executive orders or other directives compar


able to the federal ones, and every state now has a statute or executive order 
to govern construction of state projects, such as prisons and universities, that 
are exempt from local regulations. All coastal states have policies on development 
in coastal flood hazard areas. Some states have more stringent flood loss 
reduction standards for roads and bridges than those of the federal aid system. 

In some cases, the only way to preclude future uses incompatible with 

the flood risk is to permanently evacuate a portion of a floodplain and to 

obtain full title or easements on its development rights. Although this process 

(called "acquisition") is expensive, the long-term benefits in reduced flood


plain losses, protection of natural resources, and public use of the land, may 

make it worthwhile. 

Most redevelopment relating to flood loss reduction occurs after one or 

more major floods. Usually a control structure is built to protect what devel


opment remains, and a temporary moratorium is imposed to allow evaluation 

and planning. Unfortunately, legislative and regulatory requirements often 

encourage a quick return to the preflood status quo, wasting opportunities 

to mitigate and revitalize the area. 

Disaster Preparedness 

Disaster preparedness encompasses plans for mitigation, warning, and 

emergency operations; training; public information activities; exercises to test 

disaster preparedness plans; readiness evaluations; research; review and coor


dination of disaster preparedness plans and programs; and postdisaster evalu


ations. Individual preparedness is important but severely underutilized. Pre


paredness plans often are developed in concert with flood forecast, warning, 

and emergency plans. There are several federal programs for disaster pre


paredness, and every state has an integrated emergency management plan 

and an agency responsible for preparing for floods. Each Gulf and Atlantic 

FMORIASTERPREPAIENVIIESS 

*Uider the authoity tof ectin2 of theDisaster ReliefAtof 74eFidaiergency ManagementAgency 
proides up to 50% matching, grantsto hlp0 states develop and impvroveestate andlocalviplantoi aredness and 
m0itgton. ntragency flood hazardmitigation teams are fomd a reach Preiideclaredf t 
offer technical assistance to communities and statesand to identify mitigationmeasuresthat may belem entedin 
the affected areas, 

* Under Section 409 of the Act, anyjurisdiction receiving $edral disaster assistance must prepare a hazard mitigadton 
pla within 180 days of the declarion hfuture federal asistance may be curtailed if such a pla is not filed. 
n gemen Enineesande 
ice havelrmed iaprogram oforph e huca vacuion plan gin n id Atlantic states. 

The N S devlops the SW H(Se*, e and Overland Surge fm Hu e ee coasta and 
MFEMAfndstdie ruiningof iemodelsby the NW SNati luricane Center reitstormdtions, speeds 
nanintensities areprpared fro value waspv di flcneugi 

he Fede almergen i ge the AmyCorpsof he Nionl Weather Serv


plEvacuionspliIz theisuisT 
1989, when hundreds of thousands of peopwere evacuated'andjlossof lifewas keptto a minimum. 

* The FederalnEergencyManagementA0gc 0p e gtststatestodc hazar m on0projects. 
T1he FederalEnergyRegulatorCommission requires oemrgeicyaction plansattlicense projictsa penri 

cally holds in-depth exercisesto test the p0as andthe#liensee's ination of rponsibilitipeswiththe appropriate 

state and local disaster agencies. 

ITheSol Conservation Service has done flood audits of structures in the d ofthe '$nti ive in Norwich 
and tahe Qinnipiapc River in Southington, Connectict,i to complement the res se to 0flo iwarnmings.v 

p*TepaU.S.Army Corpso Engineers conductsaitechnicalrealuaions; toSdeermine w typetems and 

32 preparednesspl~~ansar areas. 0:0 000 0000 000000000000appropritae for certain 0 0 000 0 0;0 00t0 00 000 0;00000;000 0 0 


coast state has a hurricane preparedness plan completed or underway. Many 

localities also have emergency management plans, but relatively few have 

detailed plans specifically for floods, and even fewer have plans for mitigation 

after a flood. This is probably due to lack of expertise and funding to develop 

such plans, the hope that the flood problems will be taken care of through 

some structural measures, and the expectation of receiving federal disaster 

assistance when the flood does occur. 

Flood Forecasting, Warning, and Emergency Plans 

Warning systems and accompanying emergency response have long 
been recognized as effective ways to save lives and reduce flood damages in 
both riverine and coastal floodprone areas. The joint hurricane evacuation 
study is a good example of this. As the cost of the required equipment continues 
to decrease, more and more state and local governments are funding 
the development of flood warning systems and emergency plans. 

The National Weather Service conducts research, provides specific 
flood forecast and warning services to over 3,100 communities, and works 
with many of the 900 communities that have local warning systems. The 
Corps, the Tennessee ValleyAuthority, and the Bureau of Reclamation collect 
hydrometeorological data and prepare operational forecasts, often in cooperation 
with the National Weather Service, for their flood control structures. The 

U.S. Geological Survey collects streamflow and other data that can be used 
for flood forecasting. 
About half of the states are involved in flood warning, including cooperation 
in IFLOWS (the Integrated Flood Observing and Warning System) 
in Appalachia and installation of automated data collection equipment. Some 
large urban communities have included forecasting and preparedness planning 
in their operations for years, participated in regional warning systems, or have 
developed their own systems. 

University and private research has contributed substantially to the 
knowledge about and design of warning systems, disaster response, and system 
effectiveness. The private sector is vital to the design, installation, operation, 
maintenance, and modification of local flood warning systems. In many 
instances, industries have cooperated in the installation and operation of flood 
warning systems and reduced their own flood losses. 

Floodproofing and Elevation 

Floodproofing is the use of permanent, contingent, or emergency techniques 
to either prevent flood waters from entering buildings or to minimize 
the damages from water that does get in. Some of the techniques involve 
using water-tight seals, closures or barriers; using water-resistant materials; 
and temporarily relocating the contents of a building. Elevating a structure 
means raising it on fill, piers, or pilings so that it is above expected flood 
levels. Most new floodplain structures are now designed to incorporate flood-
proofing and/or elevation, primarily because it is required by the regulations 
of all National Flood Insurance Program communities. There are millions 
of existing floodprone homes to which floodproofing could be applied retroactively 
("retrofitted"), but this technique is not yet routinely used. One 
obstacle has been that flood insurance rates stay the same when a residence 
is retrofitted; the new Community Rating System of the National Flood 
Insurance Program should help remove that disincentive. 

Floodproofing is probably the tool most widely used by the private sector 
with only limited government assistance. Many of the early floodproofing techniques 
were developed by architects, engineers, and building contractors as 
they worked with individual property owners, especially on small commercial 
buildings and industrial facilities.The American Institute of Architects, the 
National Association of Homebuilders, university researchers, and private engineering 
firms have conducted considerable research on and developed techni


cal information about floodproofing. The private sector is also the source of 

many floodproofing products, such as vinyl sheathing, devices to prevent sewer 

backflow, substitutes for sand bags, equipment for filling sand bags, and flood 

shields to temporarily seal windows, doors, and other openings. 

LYCOMING COUNTY'S EARLY
WARNING SYSTEM


L4comzng County, Pennsylvania,lies almost entirely 
within the drainage area of the West Branch of the 
SusquehannaRiver and contains closeto 2,200 miles 
of streams. Most of the countys people live on or 
near the river. After majorfloodingfrom Hurricanes 
Agnes in 1972 and Eloise in 1975, a self-help early 
warning system was developedwith an initial 
investment of $500. With the help of the National 

Weather Service, forecastingprocedureswereestablishedfor 
each watershed within the county, and the 
system was put into operation within threemonths. 

Over 100 volunteer observers were recruited and 
trained to observe and monitor stream gages and 
make reports to a stream coordinator. The coordinator 
assembles the data for a watershed and conveys it 
to a system coordinator.With the help of expert personnel, 
the data is evaluated and a determination of 
expectedfloodingand appropriate response is made. 

Over the last 10 years improvementsto the system 
have been made. To assure adequate backup/for data 
transmission, the county provided National Oceanic 
and Atmospheric Administration weather radios to 

the volunteer observers,and NWS distributedbase 
station radios to the stream coordinators, In addition, 
a system of 10 automated rain gages and 4 
automnatedstream alarm deviceswas installedto 

supplementthe manual data collection. 

Examplesof Retrofitting 

) Relocation:Moving a building to high ground, 

abovc flood levels. 

(Ak, Elevation, Raziing a building so that floodwaters 
) will go under it. 

Floodwalls:Buildinga wall of concrete or earth 
to keep floodwatersfrom reaching a building, 

Dry Floodproofing: Making building walls 
watertightand sealing openingsso flood waters 

Wet Floodproofing: Altering a building to 
minimize damage when flood waters enter 

Source:FloodproofRetrofitting: Homeowner S&if.Proaeetie Behavior, 

Shirley Bradway Laska, 1991 


FLOODPROOFING AND THE CORPS 

In the early 1,960s the Tennessee Valley Authority 
and the U S. Army Corps of Engineers jointly produced 
the first comprehensive report on floodproofing. 
In 1972, afterfurther review and evaluation of 
different techniques, the Corps released Floodproof


ing Regulations, which has since been incorporated 
into or recommended by all the major regional 
building codes and many of the state and local codes. 

The Corps routinely evaluates the potentialfor using 
floodproofing in all its project feasibility studies. 

It also provides technical assistance to local commu


nities and is involved in several projects to floodproof 

large numbers of homes in communities with chronic 
flood problems. 

FLOODPROOFING IN ILLINOIS 

After floods in Illinois in 1982, 1985, 1986, and 

1987 the state provided technical assistance on flood-
proofing to victims who visited the local Disaster 

Assistance Centers. Over half of the flood victims 

eventually altered their houses and/oryards to protect 

themselves from future flooding. The average 

homeowner implemented three different floodproofing 

measures. The median costs ranged from $42 for a 

standpipe or sewer drain plug to $2,350 for sewer 

backup valves; most cost between $200 and $600. 

Most of the floodproofing measures were installed 

within two months after the flood. Those who were 

flooded again in the 1987floods found that their 

floodproofing measures were generally effective. 

One ftoodprooting technique a structure aiooat waters can pass beneath, 

is to elevate so mat 
Sebastien Roy Elemnentary 

School, Verret, Louisiana. 

Most states distribute information about floodproofing and provide technical 
assistance to individuals and groups of property owners. Several states 
have promoted floodproofing by publishing technical manuals, helping localities 
obtain funding, holding seminars for industry and individual owners, 
establishing loan programs, and cooperating with disaster assistance centers 
so that victims can begin to retrofit immediately. Local governments have 
floodproofed individual structures. A few communities have provided their 
own funding for larger projects, and others have provided technical and 
financial assistance to local businesses and residences. 

Modifying Flooding 

Modifying flooding is a floodplain management strategy of using structural 
means to alter the flood itself. Structural measures-dams, reservoirs, dikes, 
levees, floodwalls, channel alterations, high flow diversions, spillways, land 
treatment measures, shoreline protection works, and stormwater management 
facilities-permit deliberate changes in the volume of runoff, peak stage of the 
flood, time of rise and duration of flood waters, location of flooding, extent of 
area flooded, and velocity and depth of flood waters. The effectiveness of these 
measures for protecting property and saving lives has been well demonstrated. 
Flood control projects have saved billions of dollars in property damage and 
protected hundreds of thousands of people from anxiety, injury, and death. 

Throughout the second half of this century, the number and size of 
structural flood control projects have been decreasing. High construction costs 
coupled with increased cost-sharing requirements for nonfederal sponsors of 
projects have made some structures unaffordable. Structural measures also 
have been criticized for destroying riparian habitat, scenic values, and water 
quality; creating a false sense of security; resulting in eventual loss of flood 
storage capacity due to sedimentation; and inducing development in floodplains. 
These criticisms have been coupled with greater recognition that 
humans should attempt to adjust to floods and not just try to control them. 

It appears likely that the rate of construction of new flood control projects 
may hold steady or decrease slightly and that relatively few large flood control 
structures will be built in the future. Local and private construction of smaller 
flood control projects is certain to continue and may even increase. 

One issue that the nation must face in the coming decades is how to deal 
with the aging inventory of existing flood control structures. Many dams and 
reservoirs are nearing or even past their design lives, and the flood control 
capacity of many reservoirs has been reduced by sedimentation. The financial 


Structuralmeasurestodirectly control floodwatershavebeenused on virtuallyall scales-from modying a 
majorriver course, suchas thatof the Colorado,Missouri,or Tennessee,to controllingthe flow of (usually) 
insignificanttributaries. 

Concretechanneland retainingwall, SilverCreek,LeydenTownship,Illinois. 

resources are not available to undertake all required remedial actions. One 

option being actively considered and already used on a limited basis by the 

Soil Conservation Service and others is breaching small dams that are no 

longer functional. 

Investment in Flood Control 

The Flood Control Act of 1936 established the federal interest in control


ling floods on the nation's navigable waters and their tributaries. Under this 

Act, $310 million was authorized for carrying out flood control projects, with 

the Corps receiving major responsibilities for mainstem and downstream 

projects. The Soil Conservation Service was later assigned responsibility for 

flood protection on upstream watersheds. This act established the condition 

that federal involvement in flood control would be appropriate "if the benefits 
to whomsoever they may accrue are in excess of the estimated costs and if the 
lives and social security of the people are otherwise adversely affected." For 50 
years this phrase has been the basis of efforts to analyze the benefits and costs 
of water resources projects. 

In addition to the Corps and the Soil Conservation Service, the Bureau 

of Reclamation and the Tennessee Valley Authority are involved in the construction 
of flood damage reduction structures. The Bureau of Reclamation 
has planned and constructed many large irrigation and hydropower reservoir 

projects in the western United States that also provide flood control, including 
Grand Coulee Dam, the Central Valley Project, and Hoover Dam. The Tennessee 
Valley Authority has played a role in flood control since its creation in 

1933; two of its statutory purposes are "to improve navigation in the Tennessee 
River and to control destructive flood waters in the Tennessee River and 
Mississippi River Basin." 

Between 1936 and 1975 the federal government spent about $13 billion 

for dams and other structures. A few of the first flood control projects were 
financed 100% by the federal government, although most required the contribution 
of land, easements, and rights of way by state and local governments 
and maintenance of the project after it was completed. Today, however, state 
and local governments and private sponsors are required to share the costs 
of practically all flood control projects. 

State and local governments play two major roles in funding water 
resources development: constructing and operating their own projects, and 
financing their share of and maintaining the projects built for them by the 
federal government. Tremendous variations exist in the extent of state and 
local involvement in each role. As of 1988, 23 states provided technical 
assistance to communities for flood control; many more states are directly 
involved in local structural flood projects in other ways. 

Expenditures by Federal Water
Resource Agencies, 1986


Federal Agencies 

Total= -$3.4 Billion 

Corpsof Engineers (70%) 

-TVA (1%) 

SCS (8%) 

I 

U.S. Army Corps of Engineers
Expenditures
Flood Control (39%) 
$1 Billion 

Other (61%) 

WATER RESOURCES DEVELOPMENT
BY THE STATES


* Floridahas created WaterManagement Districts 
that are authorizedto levy ad valorem taxes to 
finance localwater projects. 
* In Montana, a water developmentfund was 
createdin 1981 to make loans and grantsfor all 
water developmentpurposes. 
* Louisiana, Maryland, and Minnesota have 
recentlycreated programs toprovidefinancial assistanceto 
communitiesthat developflood controlplans. 
* Washingtonprovidesgrants to communitiesto help 
maintain leveesand otherflood protectionprojects. 

DAMS AND THE FEDERAL GOVERNMENT 

*0 The US. Army Corps of Engineers has some responsibility forfive categoriesof dams:'dams planned, designed,
constructed, and operated by the Corp,; dams designed and constructed by he Cop but operatd adminined 

by otiers; dams owned by other agees in which floodcontrol storage has been provded at federal expense; dars 
for which the Corps issuespermits under its regulatory aut rity; and dams that theCorps intoianisece 
under the National Dam inspection Act of 1972 land the Dam Safety Ac of 198.; 

: Upon its creation in 1979, the Federal EEmergency Management Agencywas give rposibilit for coordinatg 
dam ia*yfetThe agency coordinates the national dam safty aprgr progress

and repor to the president;hi 
the Interagency Committee on Dam Safety; encourages the development and use of uniform; guidelinesoandstandards; 
corates dam safety research;coordinates diedevelopmentand finding of

traini maiterals; ttinformation 
exchangeamong federaland state officials;encourages the use of model state legislation and programs; and 
fosters preparedness, warning, and evacuation programs. 

* The Bureau of Reclamation is the coordinating agency for dam safety within thie epartment of the nterior.&In 
addition to responsibility for the safety of its own dams, it provides standards anii guidelines for the 0safety o dams 
owned or operated by seven other Interior agencies. 

Ile TennesseeValleyAuthority has complete responsibilityfor the planning, design, construction, 0rtio, ind 
maintenance of its dams, The TVA's situation is uique in that it constructs its dam with its own resources, 0a1da0 
exceptone of its dams are located in a single river basin and operated and maintained for the unified development 
and regulation of the Tennessee River system. 

* T17heU.S Department of Agriculture, in fulfilling assigned responsibilitiesto American agriculture, is ai permittert 
owner, manager, planner, designer, constructor, financier, and grantor of dams. Most of the dams are small, but a 
few range up to 200 feet high. 

a The Soil Conservation Service has provided technical and/or financial assistance for the install n of over 25,000 
dams. 

V The U.S. Forest Service owns 1,316 dams and administers permits for an additional 2,366. Most of the owned dams 

are designed and constructed by the Forest Service in conjunction with the management of national forestsand 
grasslands. 

' 

7TheFarmers Home Administration, Rural Electrification Administration, and the Agricultural Research Service 
also serve on the US. Department of Agriculture's Dam Safety Committee and have some tinvolvementwithdams, 
but generally depend on the Soil Conservation Service for technical assistance. 

* TheFederal Energy Regulatory Commission regulates and licenses nonfederal hydropower projects. Thecommission 
is presently responsible for the safety of about 2,000 nonfederal hydropower dams and the Department oEnergy 
(DOE) has asked FERC to be responsible for dam safety review on 20 DOE dams. 

Dams and Reservoirs 

Storing flood water in reservoirs can modify floods by reducing the speed 
at which the water flows,limiting the area flooded, and reducing and altering 
the timing of peak flows. However, misconceptions about or lack of understand-

M ing of dams can create an exaggerated sense of security. Reservoir sedimentation 
can significantly reduce flood control capacity. Competing uses of the 
THE DAMAGE PREVENTED reservoir can impair flood control because those relying on the dam for recre-

BY FLOOD CONTROL DAMS ation and water supply (irrigators, manufacturers and residential users) often 
No accurate ni/bel is ravailableof the actuail press for continued high pool levels, resulting in less storage space in the 
number o/ people protected by flood (oninol reservoir for flood waters. In addition, most dams are designed for purposes 

larms.Betreen I 960 and 1985, Corps other than flood control, although they do have the temporary effect of flood 
projerct prevented an estimated $215 billion reduction through storage. The availability of water, power, or recreational 

(198.5 dollms) in potentialf/lood damat,'es opportunities associated with dams therefore often new development
attracts 
Since its insep tion the Ten net.e 'alley regardless of the flood risk or the ability of the dam to provide flood protec-
Aunthority inultipnrpo. e darn and reserzni tion. Over time, without adequate land use regulations, encroachment onto

ni 
ternihas preventedflood daniaes 1/ihawonld the floodplain downstream of dams can prevent proper operation of the haiveamounted to nearly $3. 0)3 billion. /iThe 
caliulations are hated on the assumption that 
structure and increase exposure to flooding. Once signs of dam failure 
floariplains would have been /nst as intensively 
become visible, breaching often occurs within minutes or a few hours, leaving 

or sparsely developed if there i err no itriotwal little or no time for evacuation. The massive volume of water and its high 

rsrotection.Althount/ th/i i! not necessatily tice velocity will cause severe damage. 
case, t/iere is no inDay nifi More than 20 federal agencies and four independent officesand com


to account the d( 
velopmient that may /iaie been enco0nagn'edby missions own about 4,000 dams, have regulatory authority over 6,000 others, 
the presence of the darn. Likewitie it is /eo.ti and have various other responsibilities for additional tens of thousands of nonble 
that loten ron/ld be gteater iitho/t darns federal dams. The number of dams of all types and sizes in the United States 

ie

becaesn developtent onuldhaite taken )/arleIn is unknown, but when small dams (such as for farm ponds) are included, the

the reservfoirarea if the daimeihad not bieei total could be as high as several million. 
built. 

State regulation of dams is generally considered to have started in 
California after the failure of the St. Francis Dam in 1928. The California law 


has been strengthened at least twice since then after other major dam failures 
or near failures, and has been used as model state legislation for the review, 

inspection, certification, and maintenance of nonfederal dams. As of 1989,31 
states had statutory authority to perform all of these functions, and only two 
had no statutory authority at all. The states had a collective 1989budget for 

dam safetyof $17,668,552.The Association of State Dam Safety Officials, 
which was organized in 1984, has become a major influence in improving 
state regulation of dams. 

Dikes, Levees, and Floodwalls 

Dikes, including leveesand floodwalls, can be thought of as dams built 
roughly parallel to a stream rather than across its channel, or parallel to the 
shorelines of lakes, oceans, and other water bodies. Levees are generally con


;iDit :tE SiS Ed::E? ) X ::7i:7S::: k In :: 

An estimated 2.5,000milesof levees andfloodwallshavebeenbuiltnationwide.Theycan be veryeffectivein 
reducingflood losses, althoughareas behind leveesand floodwalls ray risk greaterthan normalflood damage. 

Floodwall,Waterloo,Iowa. 

structed of earth, floodwallsof masonry or steel. Leveeswere probably the first 
structures built for flood control by European immigrants to North America. 

The'first levee in the Mississippi Valley was constructed at New Orleans in 
1717. Levees are the most common type of flood control works. Although they 
can'be effective in reducing flood losses, a large percentage of private or 
locally built levees and floodwalls provide a low level of protection suitable 
only for agricultural purposes or are poorly designed and maintained. Levee 

or floodwall overtopping or failure is involved in approximately one-third of 
all flood disasters. 
Areas behind levees and floodwalls may be at risk of greater than normal 
flood damage for several reasons. Many floodplain residents in those areas 

believe that they are protected from floods and do not think it necessary to 
take proper precautions. Development may also continue or accelerate based 
on expected flood protection. A levee breach or floodwall failure, like a dam 

break, can release a large wave of flood waters with high velocity. After a 
breach, the downstream portion of the levee system may also act like a dam, 
catching and prolonging flooding of the once-protected area. 

The Corps has designed and constructed about 10,500 miles of levees 
and floodwalls, most of which have been assigned to nonfederal sponsors for 
operation and maintenance after construction. The Federal Emergency Management 
Agencyhas established minimum design, operation, and maintenance 
standards for levees that, for insurance purposes, must be met in order to be 
credited with providing protection against a 1% annual probability flood. The 
Tennessee Valley Authority owns and inspects 37 saddle dams and levees and 
treats them with the same criteria as regular dams, including inspections, 
instrumentation, and maintenance. Thirteen states have special regulations 
governing the construction of levees. 

THE CLASSIFICATION OF DAM
FAILURE RISK


Classificationof the risk ofpotential damfailure is 
basedon the severity of potential impact rather than 
the structuralsafety of a dam. Dams may be of very 
sound constructionbut classifiedas "high hazard" if 
theirfailure, however unlikely,could result in 
catastrophicloss of lif. Lower risk classifications 
includedams that pose a 'significant hazard"for 
whichfailure is estimatedto resultin large property 
loss; and thosethat are "low hazard,"'for which 

failure is expected to resultin minimal property loss. 
The failure of severaldams during the 1970sled to 
the evaluationand repairof numerous unsafedams 
in the United States. 

LEVEES IN THE UNITED STATES 

About 1,000 communities(5.5% offloodprone 
communities)have leveesthat protect from 1% 
annualprobabilityfloods; the length of thesestructures 
is about 9,000 miles and theyprotectabout 

5, 000 squaremiles of land. 


Structural techniques to modify channels and control stream 
flow include the constructionof diversionary walls and 
gabions-prefabricated

basketsof rock within wire cages 
used to stabilize banks. 

City Creek Canyon, Salt Lake City, Utah. 

AN ALTERNATIVE APPROACH
TO STORMWATER MANAGEMENT


The cost to communities of damages causedby 
stormwaterflooding and investment in costly channelization 
and other conduits can sometimes be 
reducedthrough different approaches to storrnuater 

management.In Arizona, for example, the larger, 

rapidly urbanizing communities all have some form 
of stormwater management requirements for new 
development.All of the larger communities in the 

state's two urban counties, which include 77% qf 

the state's population, regulatethe development of 

watersheds. 

ON-SITE DETENTION:
A MULTIPURPOSE TOOL


Principal on-site detention measures include restrict


ing land clearing, creating impervious areas, and 

providing/fortemporary storage of some or all of the 

runofffrom a property. Many urban communities 

have begun to recognize that areas devoted to storm-

water management represent a significant portion of 

their open space land and opportunities for urban 

recreation and wildlife protection. Shallow grass-

covered basins can be used as athletic fields, parking 

lots, orfor other purposes during dry periods and as 

detention basins after storms. Equipping roofs or 

parking lots for temporarily storing at least a part of 

the water that falls on them, designing streets in 

hilly areas to prevent rapid runoff incorporating 

small retention basins into landscaping, using rock-

filled pits to catch gutter runoff and using pave


ments that Let water seep through into the ground 

belowall slow runoff 

Channel Alterations 

Channel alterations increase the flow-carrying capacity of a stream's 
channel and thereby reduce the height of a flood. The various types of alterations 
include straightening, deepening, or widening the channel, removing 
debris, paving the channel, raising or enlarging bridges and culverts, and 
removing dams and other obstructions. 

Channel alteration is widely practiced by state and local governments 
to control flooding by rapidly conveying storm runoff through populated 
locales to downstream areas. The Corps and the Soil Conservation Service 
also undertake channel alterations. The Corps projects typically lie on larger 
streams and rivers, while Soil Conservation Service works mostly in smaller 
streams on the upper portions of watersheds. The Soil Conservation Service 
has provided assistance in the construction of 10,700 miles of open channels. 

The use of channel modifications has decreased primarily because of the 
potentially adverse environmental impacts. Alternative designs are now developed 
that include less straightening of channels, employ more gradual slopes, 
and use natural vegetation or riprap rather than concrete-lined channels. This 
minimizes destruction of fish and wildlife habitat, helps maintain water quality, 
and avoids undesirable downstream impacts. 

High Flow Diversions 

Diversions intercept flood waters upstream of a damage-prone or constricted 
area and convey them around it through an artificial channel or a 
designated flow-way. Diversions may either completely reroute a stream or 
collect and transport only excessive or potentially damaging flows. A negative 

aspect of such diversions is the false sense of security that may prevail in the 
protected areas along with a lack of awareness that the floodway actually exists. 
Several high flow diversions have been constructed along the Mississippi 
River. Excess water has also been temporarily diverted from the Great Salt 
Lake to an evaporation basin to prevent lakeshore flooding. 

Stormwater Management 

Stormwater management is the removal of water that falls directly onto 
properties as opposed to flood water that flows onto the property from upstream 
sources or an ocean surge. Stormwater networks have historically been constructed 
in urban and agricultural areas to remove these waters. Generally, 
the stormwater system removes the excess rainfall over a period of days and 
the temporary ponding floods only low-lying buildings and roads. A significant 
problem occurs when an agricultural zone with an adequate stormwater 
system is urbanized. Large areas are paved with roofs, roads, and parking, contributing 
to additional runoff. Often, shopping centers and other developments 
are placed on natural drainageways. The pre-existing stormwater network 
becomes inadequate for its new urban use. Localized flooding then 
occurs. 

In an alternative approach often used in new developments today, runoff 
may be retained on the site, within a regional system, and total runoff within 
a watershed may be managed so that discharges from different units reach the 
main channel at different times to reduce peak flows downstream. Natural 
drainage systems may be used instead of concrete-lined channels or enclosed 

pipes. Many local ordinances now require a zero-increment runoff for new 
development, making such on-site detention a necessity. 
Shoreline Protection 

Quasi-natural methods such as beach nourishment or artificial sand-
dune building are often used to attempt to restore an eroding beach as well 
as protect development. Long reaches of shore can be protected by artificial nourishment 
at a relatively low cost per linear foot. In addition, nourishment can 
widen a beach and increase its recreational value. A well-known beach 
nourishment project is the 10.5 miles of beach restoration in Dade County, 
Florida, which includes Miami Beach. However, these methods provide only 
temporary solutions to chronic long-term erosion caused by the diminishing 

supply of sediment in the littoral system. They also require periodic renourish



ing during their 15-to 50-year life span. Even so, they are more cost-effective 

than large structures, such as groin fields or segmented offshore breakwaters. 
These structures can also build or increase beach width as well as provide 
protection, but erosion can occur downdrift if they are not properly designed. 

Structures like seawalls, bulkheads, and revetments protect development, 
but are not intended to renourish or widen the beach. Erosion can occur in 
front of them because the natural movement of the shoreline has been affected. 
Such structures as breakwaters and jetties, which are designed to protect 
harbors and navigation channels from wave action or to stabilize inlets, can 
also cause erosion on the downdrift side if they do not include a sand-

bypassing system. 

Because of their high cost, few shoreline protection projects have been 
built without federal assistance, although most coastal states and many communities 
have participated in various ways. Some states, notably North Caro


lina, have adopted policies against new structural shoreline protection projects, 
opting to allow the shoreline to retreat naturally. Others, such as Connecticut, 
discourage construction of new structural projects, but do not specifically prohibit 
them. Still others, such as NewJersey, have active structural protection 
programs. Some states have empowered localities to establish beach protection 
districts with the authority to collect taxes to fund long-term maintenance 
programs. Private landowners also use various techniques to forestall erosion 
and reduce damages. These measures are necessarily low-cost and small-scale: 
vegetation plantings, beach fill, breakwaters, groins, revetments, bulkheads, 
and seawalls. 

Land Treatment Measures 

Land treatment measures reduce overland runoff from agricultural 
lands to streams or other waters by improving infiltration of rainfall into the 
soil, slowing and minimizing runoff, and reducing the sedimentation that can 
clog stream channels or storage reservoirs. These techniques are most commonly 
used in agricultural areas. They include maintaining trees, shrubbery, 
and vegetative cover; terracing; slope stabilization; using grass waterways; contour 
plowing; conservation tillage; and strip farming. Some measures involve 
building structures to retain or redirect runoff. Several land treatment measures 
involve little additional cos. o the farmer, and some, such as no till or 

minimum tillage, actually red..ce costs. Technical and financial assistance for 

the more expensive techniques is often provided through public sources, particularly 
programs of the U.S. Department of Agriculture. Although the 
impact of an individual measure is limited, extensive land treatment programs 
can effectively reduce flooding in small headwater areas. 

ADJUSTING TO A
RETREATING SHORELINE


Where relativesea levelrise is accelerating, coastal 

flooding and erosionwill also accelerate, placing bil


lions of dollarsworth of additionalcoastalproperty 

at risk. The nation will thus have the options of 

retreatingfrom the shoreline,armoringit with pro


tectivemeasures,or providing beachnourishment. 

The National Park Service's policy is to allow natu


ralforces to act on the shoreline ratherthan trying to 

prevent erosion with structuraldevices. The state of 

North Carolinahas taken a similar stance. Some 
federal agencieshave limited the use of structural 
measureson federal lands, but when it is economicallyjustifiable 
and environmentallyacceptable,they 
will still constructprojectstoprotectexisting coastal 
development.Likewise, many states limit structures 
in undevelopedor lightlydevelopedcoastal areas, but 
continue to permit structuralprojects to protectexisting 
development.The Coastal Barrier ResourcesAct 
excludedthe use offederalfunds in "undeveloped" 
coastalregions. 

Restorationqf beachvegetationis onemeansof slowinzg beach
erosinand transport.
Beachgraysplantingby volunteers sanddune..,


to preserve 

Newbugyport,Massachusetts. 


on floodplain management 
hazard mitigation hasbeen published in illustrated, clearly 
written manuals directedtowardboth private property 
owners and public officials. 

Muchinformnation andflood 

STATE INITIATIVES TO
EDUCATE THE PUBLIC


* lioasholdi workLhpson theNationalFlood 
InsoraniceProarain tailored to the hoslt (ounrtjs flood 
ituatisroiand invites lendeis, insurance (agents, real 
estate aOoents,

and others 

* In lennessee( a commTnity planner iill vIitil a 
floodpronrsne upon requeo,relommendaclions and 
direct theowcinerlo more intormnationor as(silsance. 

* Witaons real(stall agenItsto
nin state1(1arequires 

adl v'i p1os0a1live pwehasers if1aproperltyis shown 
aisfloodproneoln ELP rnap.s 

* Ihe llaryland Departnont of'AatulalReiourwe 
ereatedTearlesFloodhound ' a cartoon charactter 
whoappeas5 in a c0ol(011g b)ookand helps 'flood 
pupi ' learn f0lod l eftiylit/s. 
* A'rizna a -I ollrse to be presented 
(1 pieparang1llo0 
at local real estate sihools.


* Thm Oklahoma l(1islatire pa11(ed a lace in 1986
tiost readl1 il/ the pfeaa mis to h renteldhail' been
floodedlithinz the pait fiveyears and such fiot is
knowento the landlord the landlord %hallinclude
ne/iinflormatimoprolnilzInt/iand iin Ititiling as part 
of any werittenlrental aioreements. 

Modifying the Impacts of Flooding


Despite efforts to control flooding and to reduce susceptibility to it, floods 
do occur, with adverse consequences on individuals and communities. A third 
strategy for mitigating floodplain losses is to help individuals and communities 
prepare for and recover from floods. This can be done through information 
dissemination and education, spreading the costs of the loss over time, 
and transferring some of the individual losses to the community. 

It is not clear whether the present combination of flood insurance, disaster 
assistance, tax adjustments, and postflood recovery practices designed to 
implement this strategy is producing an equitable sharing of the capital and 
operating costs of floodplain occupancy among its beneficiaries, or shifting the 
costs from the individual to the public and government agencies. Neither has 
there been a clear statement of how much, if any, of the cost of floodplain 
development should properly be borne by the general public. Some argue that 
all costs should be borne by those occupying the floodplain; others that development 
of the floodplain provides economic benefits and, therefore, the 
general public should shoulder them. 

Information and Education 

Information and education activities for floodplain management have 
expanded dramatically since the 1960s, as illustrated by the number of publications, 
technical manuals, brochures, conferences, workshops, organizations, 
and media presentations now in existence. The effectiveness of this activity is 
difficult to assess. It is clear that many local officials and property owners still 
do not thoroughly understand concepts of probability, cumulative impacts, 
off-site impacts, and functional values-all of which are important for successful 
floodplain management. It is also clear that little of the material that has 
been generated and released adequately integrates the flood loss reduction 
and natural resources protection aspects of floodplain management. 

Much of the basic information about floodplain management was developed 
or sponsored by federal agencies, and includes technical design and application 
manuals, research reports, computerized databases, and public awareness 

materials. Federal and state agencies train their own personnel in floodplain 
management programs and activities. Both levels of government have actively 
provided financial and technical support to hundreds of conferences, seminars, 
and workshops on every aspect of floodplain management for professionals at 
all levels of government and the private sector, and for floodplain residents. 

In addition, states respond to individual inquiries from local officials, 
insurance agents, lenders, property owners, and the general public, and publish 
information tailored to the particular legal, administrative, and geographic 
situations of each state. Numerous nonprofit and professional organizations 
with concern for floodplain management have been formed in the last 
two decades. These organizations conduct research, produce publications, 

hold conferences and workshops, and provide a network through which 

professionals can exchange information. 

Flood Insurance 

Insurance is a mechanism for spreading the cost of losses both over 

time and over a relatively large number of similarly exposed risks. Until 1969, 

insurance against flood losses was generally unavailable. Under the National 

Flood Insurance Program, initiated in 1968 and significantly expanded in 

1973, the federal government made flood insurance available for existing 

property in flood hazard areas in return for enactment and enforcement of 

floodplain management regulations designed to reduce future flood losses. 

Although participation in the program is voluntary, of 21,926 communi


ties in the nation identified as floodprone, 18,023 (82%) had joined the pro


gram as of November 30, 1990. At the end of calendar year 1990, there were 

2.39 million policies in force with $201 billion of coverage. From 1978 through 
1989, over 384,000 claims were paid totalling over $3.1 billion. Net receipts 
from policy premiums versus claims payments varies substantially from year 
to year. From 1978 to 1989 the net operating deficit or surplus ranged from a 

NFIP Flood Claims Paid 
1978-1987 

deficit of $261 per policy in 1979 to a surplus of $98 per policy in 1987. A surplus 
was realized in fiscal years 1986, 1987, and 1988. As of October 1, 1988, 
the flood insurance fund was operating with a net surplus of $450 million, the 
result of a combination of rate increases and relatively low flood losses during 
those years. The accumulated surplus provides a reserve for years with catastrophic 
losses. 

In 1983, the Federal Insurance Administration initiated its "Write-Your-

Own" program whereby private insurance companies, under special arrange


ments, are permitted to sell and service flood insurance under their own names. 

The success of this program is evidenced by the fact that 80% of all flood 

insurance is presently sold by the participating WYO insurance companies. 

Insurance premiums are based on the location of a structure within the 
floodplain and are determined primarily by the height of the structure's lowest 
floor in relation to the height of water during a base flood. Higher rates apply 
to structures subject to fast-moving waters. New and substantially improved 

structures in the floodplain that are not properly elevated to the base flood 
level are subject to higher rates than structures already in the floodplain at the 
time a community joined the program. Since 1974, flood insurance rates have 
increased several times in order to reduce the amount of the federal subsidy 
and bring the cost of flood insurance closer to true actuarial rates. In early 
1988the administrator of the Federal Insurance Administration announced 
success in "making the National Flood Insurance Program self-supporting 

for the historical average loss year." Even so, the existing premium base is not 
large enough to permit the National Flood Insurance Program to operate on 
a fully actuarial basis. But because only 15% to 30% of the nation's floodprone 

structures are insured, there is plenty of room for increased market penetra


tion. Several strategies for increasing the number of insured structures have 
been suggested, including requiring more stringent enforcement by lenders 
of the mandatory purchase requirements, increasing public awareness of the 
flood hazard, imposing disclosure requirements on real estate agents, offering 
special insurance coverage and policy riders, and maintaining premiums at 

more affordable levels. 

Concern has been expressed that flood insurance premium costs have 
increased to a level so high that many people do not purchase flood insurance 
unless they are required to do so by a mortgage lender or unless they have 
experienced flooding. Many of those who do purchase insurance allow it to 
lapse later. The net result appears to be that only those individuals with the 
greatest risk actually purchase and maintain flood insurance. To maintain 
actuarial rates for this group, insurance rates may be forced even higher. 

Many of the claims paid out each year are on structures that have previously 
incurred damage. The Federal Emergency Management Agency defines 
these as repetitive loss structures-those for which two or more losses of more 
than $1,000 (building and contents combined) have been paid during the most 
recent 10-year period. From January 1980 through December 1989, 27.5% of 
the total losses and 32.5% of the amount paid on them were repetitive losses. 
Most repetitive losses are suffered by structures built before regulations and 
are for relatively small amounts; the building damage is usually a low percentage 
of the building value (53.2% of repetitive losses are for 10% or less 
of the building value). A high proportion of the repetitive loss claims pay


ments are for contents. 

Repetitive losses tend to be concentrated in a small number of National 
Flood Insurance Program communities, and many occur outside the designated 
floodplain. Six repetitive loss communities have had 29.7% of all the 
repetitive losses; 20 communities have had 44.3% of the losses. Although 12 
of the top 20 repetitive loss communities are coastal, only two have significant 
numbers of policies in coastal areas. Only 22 of the top 100 repetitive loss 
communities are primarily subject to tidal flooding. Because of this it is 
believed that the repetitive loss problem is more related to riverine or storm-
water flooding than to tidal flooding. 

The Federal Insurance Administration has implemented a Community 
Rating System to encourage communities to go beyond the required standards. 
The incentive will be a reduction in flood insurance premiums for policyholders 
within communities that take approved actions to reduce flood losses. 

State' 

Alabama 

Alaska 

Arizona 

Arkansas 

California 

Colorado 
Connecticut 
Delaware 
District of Columbia 
Florida 

Georgia 

Guam 

Hawaii 

Idaho 

Illinois 

Indiana 

Iowa 

Kansas 

Kentucky 

Louisiana 

Maine 
Maryland 
M assachusetts 
Michigati 
Minnesota 

Mississippi 

Missouri 

Montana 

Nebraska 

Nevada 

New Hampshire 
New Jersey 
New Mexico 
New York 
North Carolina 

North Dakota 
Oh1io 
Oklahorna 
Oregon 
Petnnsylvania 

Puerto Rico 
Rhode Island 
South Carolina 
South Dakota 
lennessee 

Texas 
Utah 
Vermont 
Virgin Islands 

Virginia 

Washington 
West Virginia 
Wisconsin 
Wyorning 

Totals 

Amount of
Claims Paid


$ 87,805,791 

332,8319 
14,064,010 
10,800,307 

108,846,266 

3,223,467 
34,906,126 
1,929,167 

101,518 
165,125,349 

8,455,396 
17,492 
10,354,101 

499,193 

81,307,867 

13,289,339 

3,101,421 
12,957,557 
48,913,951 
502,019,965 

15,921,597 
21,859,402 
40,890,955 
23,999,710 
16,518,655 

108,496,982 
113,043,717 
1,943,610 

9,460,795 

1,891,589 
3,729,914 
117,979,379 
490,587 
105,271,504 
15,495,792 

9,786,873 
29,549,982 
60,986,298 
2,404,346 
61,971,275 

32,200,608 
7,828,172 
10,324,333 

1,403,419 

8,482,208 

575,588,046 
4,439,661 

1,140,338 

2,332,664 
59,077,329 

13,196,518 

67,738,531 

3,295,144 

1,038,852 

$ 2,657,819,907 

SawtisFlood Inso ran.e Plro 


tiiers >aiona1 C.i....littee 

t tie ss defidod hy :1\4A program regulations, 
means any stae, tle District of Cothinibia, lie territories 
.od posses..... t, the United States, (fte (Ctwntiotierlw-th 

1 Prtrtc Rio and the Ttrust Territcirv of th P-acific 
Islisnds 


Amount Paid for NFIP Losses, 
1980-1989 

Total Paid = $2.27Billion 

RepetitiveLosses (33%) 

NonrepetitiveLosses (67%) 

Source. FEMA/FIA 

ACCEPTING THE NFIP 

During thefirst 15years of the National Flood 

Insurance Program, communitiesoften challengedit 
and resistedadoptingthe requiredregulations.Now, 
becausecommunitieshaveseen the regulationssupported 
in the courts, becausetherehas beenintensive 

media coverageof flood disasters,and becauseconcernsaboutlocal 
liabilityfor flood damageshave 

beenheightened,there is increasedawarenessof the 
program's benefits. As a result, NFIP regulations 

and other floodplain managementactivities have 
becomeinstitutionalizedand generallyacceptedas 
a community responsibility. 

TAX POLICIES TO MODIFY THE
IMPACTS OF FLOODING


* In 1987 Des Plaines, Illinois, begana permit 
surchargeof $200 for floodplain developmentprojects 
to help finance cityflood protectionactivities. 
* The city of Stamford, Connecticut,has required 
developersof certain projectsconstructedin the floodplain 
to contributefundsfor the operationand maintenanceof 
their automatedflood warning system. 
* After disastrousflooding in 1982, the state of 
Connecticutenactedspecial flood relieflegislation 
that included a provision for tax abatementsfor those 
whoseproperty was damagedmore than 10 % of its 
value. Towns were authorizedto abate up to one-
third of the taxes due, and the statewould reimburse 
themfor 90% of the taxeslost. Eighteentowns 
offered some tax abatementto property owners,and 
the statereimbursedthe towns a total of $49,504. 
Top 20 Repetitive Loss Communities 

'; by Number of Losses 
January 1980-December 1989 

1_ -' 1 /, , IV

I ,li

' ' 

)_7. Ct t York, 

-I 

-S.

Ne

12.SonomaCounty,3. Township of Wayne,tk1,256 
C4lifornia-604 / fi 1 5 And t ee-ey -742

~~~~-7 

Sorc: EM\ i 6. SaintChalsCut,*
i Misso~uri-204L-/'


; Ap

IL;.I8.SaintLousCuty t -----
r Missot9 

.\ f 

3,City of Houston, Texas-2,596 13.Cityof Mobile;

4, HatosCounty,Texas-2,379 Al am*-549 

4.GalvestonCounty,Texas-544 

16.CityofTexasCity,Texas-524 
20.MontgomneryCounty,TexasJ45ity SaintPetersburg,
20.C~unty,Montgoni~~~y Fflrd -533 
1.JeffersonParish, Louiiana- 7,871
2. OrleansParishLouisiana-5,153
8. St.BernardParish,Louislna -987 
10.City of Gretna,Louisiana-674 
11.Cityof Kenner, Louisiana-605 
Source:FEMA/F: IA 19. East Baton RougeParish,Louisiana-483 
5. PuertoRico -2,348 
Today, flood insurance is largely unavailable except under the National 

Flood Insurance Program. An exception is a Lloyds of London-based policy 
which has as many policyholders in Utah as does the National Flood Insurance 
Program. Some private policies or riders are available for basement 
flooding; these were initiated after the National Flood Insurance Program 
limited its coverage for basements and subsurface flows. Flood insurance is 
included as part of a comprehensive flood insurance policy for some large 
businesses with officesand land holdings in many locations, in and out of the 
floodplain. Crop insurance available under the U.S. Department of Agricul


ture's Federal Crop Insurance Corporation provides protection to agricultural 
producers from losses caused by insects, disease, fire, hail, drought, floods, 
freeze, and wind. 

Tax Adjustments 

Most provisions of federal, state, and local tax codes are designed to 

encourage development without regard to whether it might take place in a 

floodprone area, while relatively few provisions provide incentives to leave 

land in its natural state. Some tax-based incentives for development are 

reductions in property taxes, abatement or deferral of taxes to entice or retain 

businesses in an area, and the establishment of enterprise zones or other spe


cial business zones to promote development and employment in economically 

depressed areas. These make locating businesses, homes, and other develop


ment in some floodprone areas financially feasible and even attractive. On top 

of this, the federal Internal Revenue Code and many state codes also provide 

casualty loss deductions on income taxes to those suffering flood losses. After 

disastrous floods, many states and localities provide additional types of tax 

relief, reducing or temporarily suspending real estate taxes or business taxes 

for those affected by flooding, for example. 

Still, more integration of tax policies and floodplain management is 

occurring. The Tax Reform Act of 1986, for example, made major changes 

in the Internal Revenue Code, some of which have an impact on floodplain 

management. Individual casualty loss deductions under $100are now pro


hibited, and the deduction is limited to the portion of the loss that exceeds 

10% of the adjusted gross income. The new rule does not apply to business 

property. The Act also eliminated or restricted many of the tax deductions 

and credits that had been used as incentives to build in floodplains, on barrier 

islands, and at other hazardous locations. 


Flood Emergency Measures 

Flood emergency measures are typically carried out by local civil defense, 
police and fire departments, public works agencies, and public health personnel, 
supplemented as necessary by assistance from state and federal agencies. 
Emergency activities during and immediately after a flood may include 
removing people and property from areas about to be flooded; sandbagging 
around individual structures and constructing emergency dikes to direct water 
away from vulnerable areas; search and rescue; and steps to protect the health 
and safety of residents. 

To be successful, flood emergency measures must have the thorough 
involvement of the private sector, from individuals who evacuate and take 
household-level emergency precautions, to the organized group efforts like 
those of the American Red Cross local chapters. Private contractors work for 
communities and individuals to remove debris and repair homes, roads, 
bridges, and other property damaged from floods. Some states have standing 
contracts with private businesses to provide emergency services in disasters. 
The 1983 floods in Utah showed what literally thousands of volunteers, acting 
individually and in groups, can accomplish during flood emergencies. 

The Corps is the federal agency most commonly involved in flood emergencies, 
under authority of P.L. 84-99, which authorizes it to help in flood 
fighting, repair and restoration of flood control works, provision of emergency 
water supplies, implementation of advance protective measures, and the performance 
of other hazard mitigation activities. The support may take the form 
of technical assistance, materials, equipment, or services. The Soil Conservation 
Service may also become involved with emergency efforts. The Federal 
Energy Regulatory Commission requires emergency action plans for all its 
licensed dams. The Federal Emergency Management Agency helps state and 
local governments assess the extent and severity of damage in order to seek 
disaster assistance. State emergency services agencies generally coordinate state 
resources and activities during flood emergencies, and the state police and 
transportation or public works departments, the state national guard, and the 
agencies responsible for dam safety and water resources also play major roles. 

Disaster Assistance 

Disaster assistance is provided by federal, state, and local governments, 
and the private sector. It may take the form of financial relief, or of help to 
repair, replace, or restore facilities damaged or destroyed by a disaster. The 
system is most often efficient and adequate to provide the necessary financial 
relief to individuals and communities. 

The greatest source of federal disaster assistance is provided under the 
Disaster Relief Act of 1974 and takes the form of grants to the states from the 
President's Disaster Relief Fund after Presidentially declared disasters. The 
assistance is administered by the Federal Emergency Management Agency, 
which also directs and coordinates the disaster assistance functions of all 
federal agencies. The Small Business Administration issues its own disaster 
declarations and makes low-interest loans available directly to eligible individuals 
and businesses to replace or repair damaged real estate, inventory, 
or other business property. The Federal Highway Administration provides 
funding assistance for damaged highway facilities that were constructed with 
federal aid. Under the Emergency Watershed Protection Program, the Soil 
Conservation Service may directly undertake emergency work such as clearing 
debris from channels and stabilizing streambanks. As mentioned above, 
the Corps has authority to provide assistance for disaster the Corps has 

authority to provide assistance for disaster preparedness, advance protective 
measures, rehabilitation of flood control works damaged or destroyed by 
flood, protection or repair of federally authorized shoreline protection works 
threatened or damaged by coastal storms, and provision of emergency drinking 
water. The Farmers Home Administration State Director may make 
emergency loans to farmers, ranchers, and oyster planters. Under the Emergency 
Conservation Program, an Agricultural Stabilization and Conservation 
Service State Director may designate areas eligiblefor cost-sharing grants of 

up to 64 o to rehabilitatefarm lands damaged by natural disasters. 

Emergency response to Jlooaing is usually the responsibility 

of tocal agencies,with supplemental assistancefrom state 
andfederalagencies.However, private citizensaretypically 
the first to respond and provideassistanceto others. 

FIGHTING FLOODS IN UTAH 

In early May 1983 Salt Lake County, Utah, began 
24-hour monitoring of critical streams in anticipation 
of severe flooding as a resultof a large snowpack and 
unusually cold spring. The most vulnerabl flooding 

location was identifiedas 13th South, where three 

streams came together. Cityforces, with assistance 
from volunteers,built temporary dikes along the street 

so it could be used as a channel. After a sudden 
thaw on May 26, the county and city declaredan 
emergencyand flood controlplans were activated. 
Two days lateranothercreek reached a flood dis


chargenearlydouble its previous recordand went out 
of control. Volunteerswere calledin to sandbag 1.5 
miles of State Street through the city; flood waters 

were successfullycontrolledin this temporaryriver. 

During the extendedperiod of flooding and subsequent 
cleanupin Utah in 1983, volunteersput in an 
estimated50,000 days of work in Salt Lake City, 
and about 100,000 days in the rest of the county. 

The value of the volunteerwork has beenestimated 
at over $18 million. 

.StateStreet,SaltLake Cityl Utah, May 1983. (Street 
was uvedas a temporarywater conveyance path.) 


Most federal disaster assistanceis provided through 
FEMA, although the Small Business Administration, 
FederalHighway Adninistration, Soil Conservation Service, 
Army Corps of Engineers, farmers Horne Admninistration, 
and Agricultural Stabilizationand Conservation 
Servaice prograns. State and local govern-

also administer 
ments, as well as private, nonprofit organizationssuch as 
the Red Cross, are also ceatrally involved in providing aid 
following flooding. 

Disaster Assistance Center, DeRidder, Louisiana, 1983. 

THE "AVERAGE" DISASTER 

A 1990 preliminary report by the LI. S. General 
AccountingOffice noted that in an 'average" disaster 
about 2,000 individuals andfamilies seekfederal 
disaster assistance and the Federal Emergency 
Management Agency spends about $10 million. 

Although all state and most local governments have programs to coordinate 
and provide assistance during an emergency, few have special funds for 
financial assistance to victims. Most states limit their own disaster assistance 
funding to local governments, rather than extending it to businesses or individuals. 
All states now contribute some of the nonfederal share of assistance 
for Presidentially declared disasters. States may also declare their own emergencies 
or disasters; 28 states then provide assistance to localities out of a 
governor's emergency fund. 

Local governments may provide disaster assistance to their residents and 
business community, most commonly through some form of tax break. Many 
localities have joined mutual aid agreements with nearby communities to pro-

Dollars Paid for Disaster Assistance, 1965-89
All Disasters versus Floods and Hurricanes


1700 

1500 Type of Disaster 

1400 -Al! Disasters (Total = $6,735,868,000) 

1300
1200-o Floods & Hurricanes (Total = $5,185,337,000)


1100 

a


0 1000 

900

0 

800 


a, 

700C600


0 

500I
400I
300 


200rI~ 

200 -~ 
66 68 70 17'274 07 8 2 84 86 88 

Source:FEMA Year 

Number of Presidentially Declared Disasters, 1965-89
All Disasters versus Floods and Hurricanes


Tvye of Disaster 

50 * All Disasters (Total = 657) 

45 g Floods & Hurricanes (Total: = 508) 

40 1 

35 

30 

257


20 

157


10 l 

L 

66 68 70 72i74 76 78 80 82 84 86 88 

1965 67 69 71 73 75 77 79 81 83 85 87 89 
i Source:FEMA Year 

4H 


vide equipment, personnel, and other disaster assistance. Research has shown 

that local governments have the capacity to assume a much higher proportion 

of losses than they usually do within the existing framework of federal and 

state programs. 

A number of national voluntary organizations provide disaster relief 

services, primarily emergency shelter, food, clothing, and medical aid. Some 

also provide longer-term assistance, such as rebuilding homes or job place


ment. A committee known as the National Voluntary Organizations Active in 

Disaster coordinates 11private relief groups. Three of these organizations, the 

American National Red Cross, the Salvation Army, and the Mennonite Dis


aster Service, were formally recognized in the Disaster Relief Act of 1974 and 

have signed memoranda of agreement with the Federal Emergency Manage


ment Agency formalizing the provision of their disaster assistance. In addition 

to national organizations, local churches and other voluntary groups often 

provide significant assistance during and after disasters. 

Postflood Recovery 

Postflood recovery work, aided by many types of disaster assistance, 
has been largely effective at restoring flood-damaged communities and individual 
properties to their preflood condition. Unfortunately, this has not 
always been the wisest course of action, because returning to the status quo 
leaves the door open for a repeat of the disaster. Numerous recommendations 
have been made over the years to alter recovery procedures to take advantage 
of the opportunities presented immediately after a flood, when outside exper


tise and money flows into a community, damaged or destroyed facilities are 
waiting to be repaired or replaced, and local attitudes toward mitigation 

are 
more flexible than before. It was thought that this would be the best time to 

identify mitigation actions that might easily be taken and to delay reconstruction 
until wise decisions about the vulnerability of future development could 
be made. Gradually federal agency policies began to change so that over the 
past two decades individuals and communities have had to meet certain con


ditions in order to receive disaster assistance. These include protecting the 
environment, implementing floodplain management measures, purchasing 
flood insurance, and taking action to mitigate hazards. Passage of the Disaster 
Relief and Emergency Assistance Act in 1988, which allows federal disaster 

assistance funds to be spent on mitigation activities and not just to rebuild to 
the predisaster condition, signalled a new approach to postflood recovery. 

Restoring and Preserving the 
Natural and Cultural Resourcesof Floodplains 

The strategies of preserving and restoring the water resources, living resources, 

and cultural resources of floodplains are generally intertwined. The best way 
to protect these floodplain resources is to avoid development within floodplains. 
It has been suggested that stronger federal support of programs to set 

aside floodplains from development is needed, and that federal policies and 
procedures actually do not encourage and sometimes even obstruct innovative 
approaches to preserving natural floodplains. Several federal policies, for 
example, limit the features of water resources projects to those that have 
quantifiable economic benefits. Because many natural and cultural resources 

are difficult to quantify, or add only incremental benefits, the cumulative 
effect of eliminating these features may not be taken into account. 

Limited preservation and restoration can be accomplished indirectly 
through flood loss reduction activities. Numerous programs at all levels of 
government establish policies that encourage, but generally do not require, 

protecting floodplain resources. Natural resources management itself is usually 
not focused on floodplains but instead addresses a particular resource 
throughout its natural range. 

NAGS HEAD PLANS ITS RECOVERY
FROM A FUTURE FLOOD


The Town of Nags Head, formerlya quaint villageof 

seasidecottageson the OuterBanks of North Carolina, 
is now a resortcommunityfacing substantial 
growth and development. Oneof its main concernsis 
protectingthe qualityof its natural resourcesand 
preparingits residentsand thousandsof visitors for 
hurricanesand coastalstorms. With guidancefrom 

the state's CoastalArea ManagementAct Program, 
Nags Head beganpreparinga local land useplan 
that wouldincorporatea prestorm mitigationprogram, 
warning and preparedness plans, and post-
stormreconstructionpolicy. 

In developingits plan, Nags Head surveyedall its 
propertiesat risk, finding that 84 % of the town's 
2,500 buildingslay in the 100-yearfloodplainand 
44 % in the high hazard areas. There were alsofour 
public buildings,27 miles of streets, and 32 miles of 
public water mains within thefloodplain. 

After a seriesof meetings and workshops,the Board 
of Commissionersadoptedpoliciesand actions "to 
reduce,to the extent possible, future damagefrom 
hurricanesand severecoastalstorms." Thereare 12 
mitigationpolicies, includingusing the capital 
improvementsprogramto encourage growth away 
from high hazardland intopublic open space,and 
opposingconstructionoffinger canals and other 
projectsthat destroythe protectionprovidedby natural 
features. 

The poststormreconstructionpoliciesaredesignedto 

take advantage of the natural landclearanceprovided 

by severe storms. When it begins to redevelopthe 
clearedareas,the town will limit reconstructionof 
substantiallydamagedbuildingsand public utilities; 
will rebuild publicstructuresstrongenoughto be used 

as shelters,and will notpermit oceanfrontreconstruction 
until the statereestablishesthe setback line. 

(Adaptedfrom ASFPM News & Views, 1988) 

It has beendifficultto quantifythevaltueof the natural 
and cultural resource.oj'floodplainsand thereforedifficult 
to justify governmentexpendituresto preserve jfoodplains 
in theirnaturalstate.However,thereis a growing desire 

amrongthe public to rtake sure that the natural benefits of 
the riparian environwentare safeguarded 

L 


THE WILD AND SCENIC RIVERS ACT 

The Wild and Scenic Rivers Act of 1968 establishes 

as national policy the protection of certain selected 

rivers (or segments of them) with particular natural 

and cultural value, The National Park Service main


tains a list of rivers that are potential additions to 

the designated system. The Act prohibits the Federal 

Energy Regulatory Commission from licensing any 

dam or other work on or directly affecting any river 

of the system and likewise prohibits other federal 

agenciesfrom activities that would have a direct and 

adverseeffect on the values incorporated into the Act. 

Further, all federal agencies are required, as part of 

their normal planning and environmental review 
processes, to avoid or mitigate adverse effects on 

rivers being consideredfor wild and scenic 

designation. 

Regulations 

Regulatory measures are among the most widely used and most effective 
means of helping to protect the natural and cultural resources of floodplains; 
they are employed at all levels of government. There are several drawbacks to 
using them, however. Restrictions on the use of private land in order to protect 
natural resources are generally viewed less favorably by the public and the 
courts than are restrictions to protect human lives or property. Because of 
this, regulations must be well designed to avoid being ruled unconstitutional 
takings. Finally, protective regulations sometimes conflict with flood loss 
reduction measures, especially with structural works. 

Many federal environmental regulatory programs directly or indirectly 
protect floodplain natural resources. These include programs established to 
implement the Clean Water Act; the Safe Drinking Water Act; the Federal 
Insecticide, Fungicide, and Rodenticide Act; the Solid Waste Disposal Act; the 
Endangered Species Act; the Natural Historic Preservation Act; and others. 

Statewide floodplain, wetland protection, or similar regulations may be 
applied directly by a state or, as is more often the case, by local communities 
according to state-established standards. Any alteration of the natural topography 
or habitat, or any damage to flora or fauna requires a permit in some 
states. Cumulative impacts are considered during the permit review process 
in a few states, and mitigation of the loss of natural resources is often a condition 
for permit issuance. Several states specifically protect wetlands with 
programs that outline minimal criteria for permit issuance and prohibit all 
other development. 

Local regulations, such as zoning and subdivision regulations, building 
codes, housing codes, and sanitary and well codes, may directly or indirectly 
manage natural resources by including provisions for protecting habitat, water 
quality, and open space. Relevant provisions include setbacks from the shore, 
limited density in coastal areas, restrictions or prohibitions on certain kinds 
of development in such sensitive areas as barrier beaches and sand dunes, and 
specification of uses that will not degrade the natural resources of the site. 


Development and Redevelopment Policies 

Important federal policies and programs affecting the design and location 

of services and utilities in the nation's floodplains have been established in the 
executive orders on floodplains and wetlands and in accord with the Wild and 
Scenic Rivers Act and the Coastal Barrier Resources Act. The executive orders 
require federal agencies to evaluate their proposed actions in light of, among 

other considerations, the proposed impact on the natural resources of floodplains. 
Some states have executive orders to control placement of public facilities 
on floodplains, while others directly regulate these uses through statutes. 
A number of federal laws and programs provide funding and other assistance 

for acquiring and protecting floodplain land. 
States protect natural and cultural resources with open space and recreation 
programs that are occasionally linked to floodplain management. 

Most states have at least one program through which wetlands are brought 

into public ownership, although that usually was not its specific intent; fre


quently wetlands are acquired because of their habitat, open space, or other 

value. Most states have now enacted legislation to protect wetlands; many of 

these states have found that the incremental loss of small wetland areas still 

results in an unacceptable cumulative loss. In response, they are acting to 
tighten existing wetland protection programs. A related measure is mitigation 
banking programs, which provide for the creation or enhancement of wetlands 
at one site as compensation for damage that has or will occur to wetlands 
as a result of development at another site. At least 10 mitigation banks 
were functioning in the United States as of 1986. Mitigation banking is only 

appropriate in certain situations and requires a great deal of administrative 
and planning effort, financial support, and commitment. 

Several thousand communities have acquired a portion of their floodplains 
for parks, parkways, wildlife areas, conservation, agriculture, or other 
environmental or social uses. Some local jurisdictions have moved toward programs 
to combine other community objectives with floodplain management, 
including open space, hiking, cycling, water quality, aquifer protection, wetlands 
protection, and the provision of fish and wildlifehabitat. These multiobjective 

programs typically take two forms: greenway or river corridor projects and 
community redevelopment projects. The State and Local River Conservation 
Assistance Program, administered by the National Park Service, is the principal 
federal program for providing information, technical assistance, and 

limited funding for such river planning. 

Chartes River naturat flood water storage area near Dedham, Massachusetts. 

PROTECTION OF
FLOODPLAINS AND WETLANDS
THROUGH REGULATION


* Many Michigan communitieshave adoptedcombined 
floodplain and wild and scenic river regulations 
to preserve thenatural resourcesof theie areas. 
* Bevidesfloodplain regulationsthat requirepermits 
for filling, grading, orconstruction, VirginiaBeach, 
Virginia, has adoptedcoastalwetland and sand dune 
protectionregulationsthat requirebuilding setbacks. 

* A zoningordinancein Clearwater, Florida, 
includesspecialregulationsfor environmentally nitive 
areas, includingmangroveandfreshwater 
swnamps,barrier islands, coastalbeacles, natural 
drainageways,and aquifer rechargeareas. 

* In orderto reducebank erosion, increasegroundwater 
infiltration,and providewildlife habitat, several 
Californiacommunitieshaveadaptedordinances 
regulatingthe removal of riparian coveralong 
watercourses. 

* In Northampton, Massachusetts, 1,500 acres 
offloodplain alongthe Connecticut River have been 
placed in an exclusive agriculturaluse district. 
* In East Hampton, New York,floodplain regulatlionsare 
supplementedby a beachgrass protection 
ordinance,tidal and inland wetland regulations,a 
done setbackregulation,and sceniceasementsto protectwetlands, 
dunes, and otherareas. 
PROTECTION OF
FLOODPLAINS AND WETLANDS
THROUGH DEVELOPMENT POLICY


* A Glastonbury, Connecticut, floodplain regulation 
includes a density transfer mechanism under 
which developmentrights may be shifted from one 
place to another. 
* In the largestfederally funded watershed 
management project in history, the U.S. Army 
Corps of Engineers purchased 8,500 acres of 
wetlands in the Charles River watershed upstreamfrom 
Boston, Massachusetts. These wetlands 
provide 50, 000 acre-feetof flood water 
storage, eliminating the needfor a flood control 
dam or other structure and constituting significant 
areas of habitat and open space. 

* New Jersey usedfundsfrom the U.S. Fish 
and Wildlife Service's Federal Aid to Wildlife 
Fund to acquire additions to the 4, 400-acre Cape 
May Wetlands, which the state maintains as a 
wildlife refuge. An adjacent 315-acre salt marsh 
was purchased, and the owner of the property donated 
25% of the land to the state, providing the 
state 's required matching funds. 
Continued on next page 


PROTECTION OF
FLOODPLAINS AND WETLANDS
THROUGH DEVELOPMENT POLICY


Continuedfrom previous page 

* When the Wynoochee Dam was constructed in 
Washington State, a portion of wildlife habitat 
was lost under the lake and a number of elk and 
deer were left homeless. To mitigate the loss, the 

U.S. Army Corps of Engineers acquired 1,034 
acres of land to provide replacement winter 
rangeland. Within each area, cultivated fields 
supply winter forage, while the remaining area 
servesas buffer and as habitat. 
* Florida's Save our Rivers Program is one of 
several that have protectedsubstantial acreagefor 
habitat, water quality, watershed protection, and 
recreation.Land has beenpurchased to restore 
channelized or impounded rivers thatfeed the 
Everglades, to restorethe Kissimmee River to its 
original channels, to conduct a pilot project on 
marsh habitat renewal, and to preserve parts of 
the Green Swamp. 
* The Mecklenberg County, North Carolina, 
Greenway Master Plan provides for the preservation 
of floodplains along more than 20 creeksfor 
passive recreation,habitat protection, and reduction 
of flood damages. A network of greenways is 
planned that will include 4, 000 acresand 60 
miles of trails. As of 1986, over 1, 000 acres 
had been acquired through donations, local park 
bonds, and dedications. 

PROTECTION OF
FLOODPLAINS AND WETLANDS
THROUGH TAX ADJUSTMENTS


At least 43statesoffer real estatetax incentives to 
leaveland in agriculture, forestry, and certain other 
open space uses; undevelopedfloodplainsqualify 
under some of these statutes. 

* A Floridaprogram earmarksfor the Water 
Management Lands Trust Fund the revenues from 
a documentary tax of $.075 per $100.00 on all real 
estatetransactions. The money is used to purchase 
and managefloodplains and wetlands. Revenues 
over the next 30 years are expectedto approach 
$1 billion. 

* Minnesota's Tax Exemption and CreditProgram 
has two main components. Underthefirst, eligible 
wetlandsare exemptfrom property taxes. Under the 
second,landownerswho agreenot to drainwetlands 
in a given year receivea tax credit. Excess creditsfor 
wetnd property maiybeapplied tothe landowner's 
taxliabilityfor contiguousproperty. The state reimbursescountiesfor 
revenueslost due to the exemptions 
andfor the value of the tax credits. 

Ftoodplain management efforts have sometimesbeenunsuccessfulbecausethey are seen as benefitting only 
selectgroupsat the expense of an entirecommunity.Therefore,somejurisdictionshavedevelopedprograms 
thatcombineothercommunityobjectives-thedevelpmentof open space and recreation

facilities,or the protectionof 
wetlands and waterquality, for example-withfloodplainmanagement. 

Greenbeltpark, Maryville, Tennessee. 

The private sector, operating largely through private, nonprofit organizations, 
is heavily involved in acquiring land to protect it for open space and 
habitat, and much of that land is wetlands or floodplain land. As of 1989the 
Nature Conservancy was responsible for the protection of 3,643,352 acres in 
50 states, Canada, Latin America, and the Caribbean. The Audubon Society 
and Ducks Unlimited have active programs to help preserve wetlands. 

Information and Education 

Information, education, and technical assistance are becoming more 
important as natural resource managers and interest groups realize the benefits 
of a public that is well-informed about natural systems and about the consequences 
of decisions that affect them. Technical information and public education 
about the natural and cultural resources of floodplains is provided by 
the Environmental Protection Agency, the U.S. Fish and Wildlife Service, the 
Office of Coastal Resources Management, and other federal agencies through 
press releases, newsletters, magazines, and television programs. Most states 
have active programs within their natural resources, environmental protection, 
and parks and recreation departments that prepare and distribute literature, 
films, and other materials. Many offer instructional courses to staff and officials 
of local communities. Natural resource inventories and mapping are 
major components of many state programs. Hundreds or thousands of private 

organizations exist across the country to inform and educate the public about 
natural resources, including those on floodplains. Environmental values are 
widely taught in schools at all levels, and popular television programs reach 
a wide audience. Research is an important predecessor to education and 

technical assistance, and the information base on natural resources is being 
broadened continually. 

Improved documentation and quantification (including dollar values) 
of the value of natural floodplains are needed to improve public understanding 
and acceptance of the need for protection. For example, few developers 
seem to realize that floodplains and wetlands have great aesthetic appeal, that 
in their natural state they can simultaneously enhance property values and 
continue to fulfill their normal natural and cultural functions. 

Tax Adjustments 

Positive incentives for the preservation and restoration of floodplain 
resources can be provided through several kinds of tax adjustments, although 
this technique has not been widely used. Federal income and estate tax benefits, 
which are available to individuals and organizations who donate land and 
provide easements to governments and eligible nonprofit organizations, have 


been a major factor in facilitating private donations of property with valuable 

wildlifeand habitat functions or historical significance. Most conservation 

organizations are tax exempt, and many of them are active in protecting the 

natural and cultural resources of wetlands. Almost all states offer tax incen


tives for open space uses. 

Administrative Measures 

Many different administrative measures can be used specifically to pre


serve and restore the natural and cultural resources of floodplains, including 

restrictions or conditions on contracts, grants, loans, permits, and licenses; 

encumbrances during land conveyance; delegation of responsibility for flood


plain activities to a specific authority; comprehensive planning; systematic 

review of agency programs to identify opportunities for preservation and restoration; 
and coordination among federal, state, local, and private agencies to 
implement unified efforts. Some of the most important administrative meas


ures address the inventory, classification, and mapping of wetlands, wildlife, 
aquifers, and other natural resources. It is necessary to know what natural 
resources exist in the floodplain and what their individual and collective value 

is before making land use decisions that will sustain those values and functions. 

Planning historically has been used by governments for many kinds of 
activities besides natural resources management. Comprehensive planning 
provides an opportunity for taking a holistic view of floodplain 

resources 
while also meeting other local needs, such as water supply, agricultural erosion 
control, recreation, and economic development. This sort of planning is 
getting increasing attention at the state and local level, and typically incorporates 
several of the tools discussed above. 

Multiple Use Planning for a Floodplain 

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FLOODPLAIN MANAGEMENT
TERMINOLOGY


Some misperceptions aboutfloodplain management 
are the result of simple lack of understanding For 
example, probably the most misunderstood concept is 
the "100-year flood. " The term is often taken literally, 
causing individuals to believe, incorrectly, that 
if they or their community haveexperienceda 100


year flood, a similar one cannot occur for another 
century. The terms "1% annual chance flood" and 
"national base flood standard" have been suggested 
as less-misleading substitutes. 

Use of the term 'floodproofing -also can give a 

false senseof security about susceptibility toflood 
damage. The techniques involved in floodproofing do 
not make a structure completely safe from flooding 
The term 'flood-resistant construction'' has been 
suggested as an alternative. 

REGULATION AND
PUBLIC AWARENESS


Many regulatory measures have been instituted by 
governments in an effort to force individual awarenessof 
flood hazards and protective action. For 
example, the National Flood Insurance Program is 
voluntary,but changes have been made in the law 
since it was passed in 1968 in order to encourage 
greater participation. Primary among these was the 
Flood Disaster Protection Act of 1973, which prohibits 
nonparticipating floodprone communities from 
receiving disaster assistance after a flood. Another 
mechanismintended to promote awarenessand compliance 
is the provision that federally insured Banks 
and other financial institutions require purchasers of 
homes and other structures in the floodplain to take 
out flood insurance. This procedure has not been 

wholly effective because the institutions currently are 
not penalized if they fail to comply. 

Previouspage. CharlesRiver watershed,Afassachusetc. 

Perception and Awareness 
of Floodplain Losses 

Both individual and institutional perception and awareness of flood risk and 
vulnerability affect floodplain management. Although substantial progress has 
been made in increasing institutional awareness and response, individual perception 
and awareness generally falls far short of what is needed. This shortfall 
makes itself unpleasantly felt in the unwise development of flood hazard 
areas and in disregard for the value of natural floodplains. 

Recognition of Risk 

Local perception of flood hazards-by both governments and floodplain 
residents-is related to previous experience with flooding; the extent to which 
the floodplain is developed; the existence of structural control measures; the 
seriousness of the flooding in relation to other community problems; and attitudes 
about land use, water resources management, and regulations. In general, 
the threat of damage from coastal flooding seems to be taken more seriously 

Although public knowledge concerningflood risks hes increased significantlyin the last 30 years, development 
in hazardous areas is still occurring. 

Flooding and alluvialfan, MagnoliaSpring Canyon, RanchesMirage, California, july 197.9( 

by communities than is damage from riverine flooding. Because most people 
discount the probability of loss from infrequently occurring events, such as 
large floods, individual and community experience with flooding results in 
both heightened perception of risk and increased attention to solving flood 
problems. The perceived seriousness of the flood problem is directly associated 
with the extent of floodplain development and existence of intensive 
land uses in the hazardous area; increasing development may result in greater 
awareness of flood problems. The presence of structural flood control measures 
has varying effects on perception of risk and subsequent responses; structural 
measures may contribute to a sense of complacency, as though the problem 
were "solved." 

Private citizen perception of risk may be quite different from that of local 
officials. Even if the risk is acknowledged, the advantages of a floodplain location 
to the individual property owner may seem to outweigh the disadvantages. 
Homeowners also may be more concerned with the effect of floodplain regulations 
on resale value than with the effect of a potential flood on the house or 
property itself. Some studies have found that even after a control structure is 
built, local governments remain concerned about a flood problem, while the 
citizens themselves tend to forget about the threat. Both individual and community 
perception of risk may be tempered by other considerations, such as 
apprehension about the potential secondary effects of land use management-
reduction in property values, slowed economic growth and development, 
reduction in the tax base, and increased construction costs. 


Informing and educating the public about both flood risk and about the 
importance of the natural and cultural resources of floodplains is an ongoing 
effort. Much research has examined ways to provide information and to make 
people take action, and new techniques are being sought continually. Typical 
means of providing information to the public include distribution of pamphlets 
and other publications; use of radio, television, and newspapers; placement 
of warning signs; and many other more imaginative methods. A few 
jurisdictions require real estate agents to provide flood and other hazard 
information to prospective buyers of homes. 

Awareness of the Value of Natural Floodplains 

The protection of the natural and cultural resources of floodplains is 
beginning to emerge as a popularly expressed environmental objective; it is 
already encompassed in the broader environmental goals embraced through-PUBLIC SUPPORT FOR WETLANDS 
out the nation. The general level of public environmental awareness and sup-Concernfor the loss of wetlands and supportfor their 
port for all types of protection programs has increased dramatically in the protection appear to be increasing.A 1982 Harris 
past 25 years, and the importance of preserving wetlands, protecting endan-pollfound that 83% of respondentsfelt that it is 

gered species, and maintaining water quality is widely recognized. "very important" to preserve the nation's remaining 

This kind of awareness represents a potentially broad base of public sup-wetlands. A 1985 poll reaffirmed this broadsup


port for floodplain management. Unfortunately, this voiced support does not port: 85% of those polledfavored strict enforcement 
necessarily translate into action, particularly when an individual's own prop-of the Clean WaterAct and its wetlands protection 
requirements.

erty is involved. Any restriction on individual property rights may be strongly 
resisted, or the loss of natural values may seem inconsequential because of the 
small area affected. 

Protecting the Environment 

Percentage of the U.S. population that agreed with the following
statement:


100 l 

Protecting the environment is so important that
requirements and standards cannot be too high and
90 continued environmental improvements must be made
regardless of cost.
80 1


70 

60 


C.)

0) 1inv , 

CD 

40 

30 

20 

10 

0 l 

1981 1984 1986 

Year 


METEOROLOGICAL DATA: THE NWS 

The collection and analysis of weather data for 
floodplain management-precipitation intensity, 
extent, and duration; wind data; and temperature-

is the responsibility of the National WeatherService. 

The NWS's data collectionsystemextends through


out the 50 states, offshore, and across the Pacfic 

Ocean, and now consists of about 230 staffed stations, 

165 automatedstations, and almost 400 stations 

under contract. In marine locations,automated 

mooredand drifting data buoys are used. A network 

of automatic hydrologicalobservingsystem stations is 

operatedto provide near real-time data of river stages 

and rainfall. The NWS also operates 128 weather 

radar stations that provideinformationon areal 

coverage,height, intensity, and movementof storms 
for warning and forecasting and hydrological and 

climatologicalprograms. Over 1,300 ships report 

data systematically, and 300 others report data 

whenever they are in waters covered by NWS fore


casts. 

HYDROLOGICAL DATA: THE USGS
AND THE EPA


Water data have been published annually by the 

US GeologicalSurvey since 1890. Records are 

now published annuallyfor each state and main


tained on a computerized data base, the National 

Water Data Storage and Retrieval System. It 

includesdata from USGS surface water records, 

with an indexfor the 320,000 water data storage 

sites; over 240 million daily parameters such as 

streamfiow, groundwaterlevels, specific conductance, 

and water temperatures; 460,000 recordsof annual 

maximum stream flow and gage height values; 2.3 

million analytical results describing biological,chem


ical, and physical water characteristics;and construc


tion history, geohydrologicdata, and one-time field 

measurements on 850, 000 sites. The Environmental 

ProtectionAgency has a water quality data base of 

nationwide informationon water quality, water 

quality standards, point-source pollution,fish kills, 

waste abatement needs, and other topics. 

Knowledge, Standards, and Technology 

Effective floodplain management requires a sound understanding of the 

physical, biological, and chemical processes that affect flood hazards and 
the natural resources of floodplains, as well as an appreciation of the social 
processes involved in human interaction with them. The last 25 years have 
witnessed a rapid expansion of the knowledge, information base, and technological 
expertise in floodplain management-products of the combined efforts 
of governments at all levels, academic institutions, and the private sector. 

Climate Change and Weather Forecasting 

One of the basic assumptions of hydrology and floodplain management 
has been that long-term climate is constant. Over the past few decades, however, 
new evidence has suggested that climatic changes can take place rather 
quickly (over a decade or so) and last for half a century or more. Therefore, 

the traditional 30-year averages of various climatic parameters-precipitation, 

for example-that have been the basis of past policy may be misleading for 

decisions involving long-term consequences. 

During the 1970s and 1980s, indications of a global warming trend 
increased, and some scientists hypothesized that human use of fossil fuels was 
amplifying the greenhouse effect sufficiently to cause changes in global climate. 
The normal historical relative rise in sea level is expected to continue over the 
next century, and as a result of the human-induced climate changes, the rate 
of rise is anticipated to increase. The predicted rise in global mean sea level 
is about 20 cm by 2030, and 65 cm by the end of the next century, with significant 
regional variations. This could have profound flooding implications. 

Streamflow Data 

Over 90% of the 7,492 daily-record stream gages in the United States 
are operated by the U.S. Geological Survey in cooperation with a local sponsor. 
Since the first stream gage was established in 1889, the U.S. Geological 
Survey network expanded until 1980, but has declined since then, largely due 
to reductions in funding by local cooperators. This makes spatial and temporal 
consistency in gathering these data difficult. Even though information 
about runoff from small watersheds (between one and two square miles) is 
important for many purposes, including highway drainage design and urban 
drainage analysis, almost all of the nation's stream gages are located on larger 
watersheds. To partially fill this gap, the Agricultural Research Service has 
gaged hundreds of plot-sized watersheds to measure runoff for individual land 
uses and soils. 

Hydrology and Hydraulics 

Hydrologic parameters of importance to floodplain management are 
flood peak flows; flood volumes; time of concentration and travel; rate of rise; 
water velocities;sedimentation and degradation of flood channels and floodplains; 
flood elevations; the effect of geomorphology on floods and vice versa; 
the hydraulics of flood channels, floodplains, and human-made structures; 
and water quality as affected by floods. These characteristics and their interrelationships 
are generally modeled mathematically. 

Inexpensive, easy-to-use computers have made it possible to apply 
accepted methods of hydrology and hydraulics analysis to many floodplain 
management activities. The susceptibility to flooding of small developments 
and even single structures now can be evaluated relatively quickly and inexpensively.
Researchers and a few practitioners are using two-and three-
dimensional analyses of flood flows to obtain more realistic and reliable results 
than those yielded by the step-backwater analysis. Several models and methods 
are available for mapping the 100-year flood in coastal areas, for determining 
stillwater flood elevation from hurricanes along the Atlantic and Gulf coasts, 
and for accounting for the effects of wave heights, wave runup, and marsh 
grass. Other models address flooding on the Great Lakes, flooding from 
tsunamis, and other special situations. Sediment transport models are being 
developed, calibrated, and applied in many areas. All these techniques, which 


I


In recent years, microcomputers have made it possible fir agencies and jurisdictions at all levels to use
sophisticated hydrologic and hydraulic models to analyze potential flooding at virtually any scale.


Microcomputerworkstationat the Floodplain Management Section, Louisiana Department of Transportation 
and Development. 

only a decade ago were very expensive and hence infrequently applied, help 
evaluate the effects of future urbanization, structures, and other land use 
changes. Although the computer revolution has improved many aspects of 
flood hydrology and hydraulics, it has also made possible misuse of the standardized 
techniques by those not fully aware of the assumptions and limits 

inherent in the methods. 

Flood Forecasting and Warning 

Weather forecasting, and hence flood forecasting, is improving with 
remote sensing capabilities and the availability of more real-time data. New 
radar equipment, such as NEXRAD, and other tools promise better precipitation 
forecasts for small-scale storms and flood forecasting for small watersheds. 
The combination of new satellite data on snow pack and real-time data 
on precipitation and temperatures may be combined with established runoff 
models and recurrence interval techniques to produce seasonal flood forecasts. 

There are a small number of automated flash flood warning systems 
throughout the country, notably in Arizona, California, Colorado, Connecticut, 
Maryland, Nevada, New York, Pennsylvania, and Texas. The performance 
of these systems has been uneven; most have not been tested under actual 
flooding situations to determine if they will indeed provide the anticipated 
level of warning. As the technology improves and operation and maintenance 
experience is gained, additional automated systems will come into use, significantly 
reducing the loss of life from flash floods. 

Soil Identification and Mapping 

Soil maps and data have proven useful in identifying and classifying 
floodplains and wetlands. The modern soil survey, with improved techniques 
and standards, began in the mid-1950s. By 1983, the Soil Conservation Service 
had mapped and classified about two-thirds of the U.S. land area (except 
Alaska), or nearly 1.3 billion acres. The Soil Conservation Service expects to 
complete soil surveys for the entire country by 2000. The agency is beginning 
to digitize existing soil surveys, and most of the remaining soil survey maps 
may be prepared with digital methods at the outset. This should improve the 
level of detail of soil classifications, standardize the map scales, and provide 
additional supporting information. 

COMPUTER MODELS FOR
HYDROLOGY AND HYDRAULICS


Computer programs like the Soil Conservation Serv


ice's TR-20 and the US. Army Corps of Engi


neers' HEC-1 can be used to mathematically model 

hydrologic conditions based on such parameters as 
flood peaks, volumes, rate of rise, and velocity. 

Other programs in use today are the Soil Conserva


tion Service's TR-55for small urban drainages and 

the Environmental Protection Agency's SWMMfor 

urban drainages where water quality is important. 

To determine a water-surface elevation for a single 
point on a stream, the Manning equation is often 
usedand can give good results where normalflow 
prevails and there are no downstream obstructions. 
However, when there are obstructions or other special 
conditions, a backwater analysis is used, and computer 
models have been developed to perform it as 
well. The most widely used backwater model is the 
Corps' HEC-2. A special dynamic routing model 
has been developed by the National Weather Service 
forflood routing and inundationfrom dam breaks. 

The NWS alsodeveloped the first widely applied 

model, known as SPLASH, for early mapping of 

coastal flood zones under the National Flood Insur


ance Program. A more sophisticated model, SLOSH 

(Sea, Lake, and Overland Surgefrom Hurricanes), 

was developed in 1975 to modelflood levels at the 

coastlinefor hurricanes of a particular magnitude, 
forward speed, and track. Today, the Coastal 

Flooding Hurricane Storm Surge Model is used 

by the Federal Emergency Management Agency to 

analyze coastal flood hazards. 

Warningsiren tied to flood sensors, Lavaca River, near 
Hallettsville,'lixas. 


THE COST OF FLOOD MAPS 

The Federal Insurance Administration now spends 

about $36 million annually to keep published flood 

risk information updated and current and to provide 

detailed flood risk data where none existed before. 

Of this amount, about $4 million annually is spent 

to distribute about seven million maps to states, 
communities, lenders, agents, banks, consultants, 
and others. 

Mapping Flood Hazards 

Nationwide mapping of floodprone areas may well be the single greatest 
achievement in floodplain management to date. Before enactment of the 
National Flood Insurance Act, floodplain mapping was done through the 
programs of the Corps, the Soil Conservation Service, the U.S. Geological 
Survey, and the Tennessee Valley Authority. Each agency mapped floodplains 
according to its individual authority and primary mission, and often on a 
project-by-project basis or only after major floods. The Corps compiled a 
national list of incorporated communities with flood problems and in 1962 
began mapping and providing the information to individual communities in 
floodplain information reports. Mapping of floodplains for the National Flood 
Insurance Program began in 1968, when the Federal Insurance Administration 
began producing temporary maps to show approximate boundaries of 
floodprone areas in identified communities and entered into cooperative 
efforts with other federal agencies and contracts with private engineering 
firms to develop methods for preparing more detailed maps. By 1990 more 
than 12,000 new flood insurance map studies had been initiated and over 
1,700 restudies undertaken at a cost of nearly $900 million. In addition to 
contracting with numerous private firms, the Federal Insurance Administration 
used the resources of the Corps, the U.S. Geological Survey, the Soil 
Conservation Service, the Tennessee Valley Authority, the Bureau of Reclamation, 
the National Oceanic and Atmospheric Administration, the Delaware 
River Basin Commission and the Susquehanna River Basin Commission, and 
some states to perform this work. 

Twenty-three states fund and prepare their own floodplain maps to complement 
the National Flood Insurance Program-to provide greater detail or 
a better scale, to reflect changes in development or hydrology, to extend mapping 
beyond corporate limits, to meet special requirements, or to cover special 
natural values. In the past few years, communities themselves have become 
more involved in mapping, either because of unique floodplain problems 
or because comprehensive local programs require more specialized mapping. 
In addition, private consultants frequently perform hydrological or drainage 
studies for subdivisions and other developments. These studies form the basis 
for many amendments and revisions to original flood insurance maps.

__*~~~~~~~~~~~~~~~~ l____1 

The foundation of the National Flood Insurance Program io accurate maps of hazard areas in floodprone 
cornmunities. The program has been producing such maps since its inception in 1968 
Flood Boundary and Floodway Map of the Fishkill, New York, area. 


Understanding and Mapping Wetlands 

Since the 1970s significant progress has been made in both scientific and 
public awareness of the value of wetlands. In 1986 the Environmental Protec


tion Agency adopted a plan of research on ways to create, restore, and enhance 

wetlands and their functions. National wetlands mapping is being performed 

by the U.S. Fish and Wildlife Service. The detailed (scale 1:24,000) wetland 

maps are used by local, state, and federal agencies and private organizations 

for many purposes, including comprehensive resource management plans, 

environmental impact assessments, permit reviews, facility and corridor siting, 

oil and chemical spill contingency plans, natural resource inventories, and wild


life surveys. They show the location, shape, and characteristics of wetlands 

and deepwater habitats on a U.S. Geological Survey base. Wetlands are clas


sified according to the Fish and Wildlife Service's wetland classification system. 

Maps have been done for 65% of the lower 48 states and 20% of Alaska. In 

addition, many states have developed their own wetlands mapping programs. 

Understanding Natural and Cultural Resources 

As discussed in Part II, the nation's floodplains contain some of its 
most important natural and cultural resources. A wide variety of data sources 
now provides information about these national assets. For example, the U.S. 
Environmental Protection Agency maintains several dozen water-qualityrelated 
data bases, and the U.S. Geological Survey compiles extensive natural 
resources data through its Water Data Storage and Retrieval System and the 
National Water Data Exchange. Additionally, the U.S. Fish and Wildlife 
Service, as part of its National Wetlands Inventory, is developing a computer


ized multidimensional wetlands mapping scheme for the entire country. The 

U.S. National Park Service has established the Nationwide Rivers Inventoryof more than 1,500river segments and maintains much other data on both 
natural and cultural resources. NOAA's National Ocean Service and National 
Marine and Fisheries Service maintain natural resources data in several data 
bases as part of NOAA's responsibilities as the nation's principal marine 
science agency. The Soil Conservation Service oversees the National 
Resources Inventory-a survey of land use and quality, based on 160-acre 
units across the United States-and the U.S. Forest Service similarly keeps 
extensive information on lands within the national forest system. 
Beyond these federal resources, state agencies, private organizations, and 
universities also maintain comprehensive data describing many aspects of the 
nation's cultural and natural resources. 

Remote Sensing Techniques 

In the past 20 years the availability and analysis of high-altitude photography, 
satellite imagery, and other forms of remote sensing have increased 
tremendously. Systematic comparison of images from different times yields 
information on changes in land use, which can be used to help assess many 

natural resources and identify areas where future flood damages may occur. 
After the land uses and natural resources of an area are calibrated, most of 
the subsequent analysis can be automated. So far these techniques have had 

limited application in relatively small areas of the nation's floodplains, but 
technological advances in computer capabilities and data management systems 
should accelerate the use of remotely sensed data in the near future. 
At least one Arizona community uses periodic aerial observations to look 
for floodplain violations. Aerial photography combined with floodplain maps 
has been used in some communities to count the number of structures within 
selected floodplains. Other communities have used or plan to use low-level 

aerial photography after floods to help determine the extent of flooding and 
damage. As digital mapping becomes more widespread, it will become easier 
and more inexpensive to monitor floodplain activities through remote sensing. 

Geographic Information Systems 

Many organizations now make routine use of geographic information 
systems (GIS)-computer systems that allow users to collect, manage, and 
analyze large volumes of spatially referenced and associated attribute data-

HENDERSON COUNTY'S GIS 

The HendersonCounty, North CarolinaSoil and 
WaterConservationDistrict is one of thefirst in the 
nationto install a microcomputer-based geographic 
informationsystem toprovide betterinterpretative 

soils information. The county'spublishedsoil survey 
has been digitized and storedin the system, and the 

computercan capture, store, analyze, and retrieve 
soils maps and othergeographicdata. Fundingfor 
the demonstrationprojectwas provided by the Ten


nesseeValleyAuthority, supplementedby the Soil 
ConservationServiceand the HendersonCounty 
Commissioners. 


AVOIDING CONSTITUTIONAL
CHALLENGES TO REGULATIONS


70 reducethe chances of having their floodplain 
managementregulationsfound unconstitutional, 
manyjurisdictions have 

* adoptedregulationswith stringentperformance 
standardsratherthan simply prohibiting all 
activities in hazardareas; 

* mappedfloodplains in more detailand more 
accuratelythan has the National Flood Insurance 
Program; 

* providedreal estatetax breaks for tightly controlledland 
to diminish thefinancial burdenof 
owners whose use of their property is greatly 
restricted, 
* improvedtheirpermitting and record-keeping 
proceduresto include detailedstatementsoffindings 
on denials in order to provide a better 
defensein court. 
for a wide variety of purposes, including natural hazards and natural resource 

management. GIS-generated maps are easily manipulated and can be up


dated at a low cost. However, GISs have not yet become widely used, mostly 

because the initial cost of digitizing the needed information for input into a 

GIS system can be formidable. Another handicap is that the different systems 

now in use are not always compatible. Once these obstacles are overcome, 

GIS technology will allow planners and managers to more easily obtain and 

apply the information they need to make wise decisions about floodplains. 

The Federal Emergency Management Agency is developing a standard for 

digital flood insurance maps in public domain format and has committed to a 

program to digitize the maps for over 340 metropolitan counties with large 

amounts of property at risk from flooding. 

Regulatory and Design Standards 

Over the past 20 years numerous standards of terminology, procedure,
performance, and quality have been developed in floodplain management.


They include both prescriptive standards (clearly identified limits set by law, 

policy, or custom), and performance standards (requirements that a specified 

goal be reached by unspecified means). Some of these standards are freely

adopted, others are met in response to an incentive, and stillothers are required 

by law. Many manuals and technical reference volumes have been developed 

to assist builders and regulators to meet the performance standards required 

by the National Flood Insurance Program. Having these standards has 

provided a uniform means of applying, reviewing, and evaluating the design,

construction, and regulation carried out in support of floodplain management. 

Not all aspects of floodplain management are amenable to nationwide
standardization. There have been no national standards established for mini-


mum setbacks from river channels, although there are some statewide standards 
for designated streams, lakes, and other water bodies. Lincoln Township, 
Michigan, for example, requires setbacks of 110 feet from dune and bluff areas 
on Lake Michigan, while Wisconsin requires a minimum setback of 75 feet 
from the ordinary high-water mark. There are no national standards for dam 
and reservoir construction; instead, each federal agency has its own set of 

criteria. Likewise, each of the three agencies (the Corps, the Soil Conservation 

Service, and the Bureau of Reclamation) that constructs federally funded 

levees has its own policies for construction and maintenance. 

Judicial Support for Floodplain Management 

Over the last few decades the types of lawsuits and the specific issues liti


gated in floodplain management have changed, reflecting the predominant 
techniques of the time and general status of the relevant law. Before 1968, 
most litigation challenged the power of governments to undertake flood control 
measures and to regulate floodprone lands. From 1968 to 1978 concepts of legal 
liability expanded and government defenses to it diminished. Constitutional 

challenges to regulations increased and shifted from broad constitutional 
attacks to specific challenges to the reasonableness of particular measures. 
Since then, courts have continued to hold governments liable for their actions 
that increase flood damages. The number of constitutional challenges to 

regulations has diminished, however, due to the widespread judicial support 
for regulations over the previous 20 years. Most recent cases have addressed 
relatively technical issues, such as the validity of nonconforming use provi


sions and setbacks. 

Constitutionality of Regulations 

Floodplain management regulations have been challenged as unconstitutional 
on two fronts: as violations of due process guarantees and as takings of 
private property. The due process claims, which were based on a general legal 

argument that the federal, state, and local governments had no legal authority 

to regulate activities on floodplain lands and waters, have almost disappeared 
over the years as the statutory authority to regulate was clarified and strengthened. 
With the exception of a few cases in which regulations prevented all 


economic use of floodplain property, courts likewise have upheld the general 
validity of floodplain regulations against claims that they take private property 
for public use without payment of just compensation, in violation of the Fifth 
Amendment to the U.S. Constitution. These rulings are consistent with a 
much larger body of law in which courts have upheld other land use regulations 
against claims of taking, despite the impact of the regulation upon property 
values. Floodplain management regulations have been supported for a 
number of reasons. 

* The rights of private landowners to their water-oriented lands are 
subject to public trust and navigable servitude rights and interests. 
* Courts give great weight to protection of public health and safety 
and have, without exception, sustained regulations needed to prevent 
nuisances (such as blockage of flood flows) and to prevent private 
actions that may threaten public or private safety on other property 
(such as construction of dams). 
* Over the past 20 years courts have upheld performance standards such 
as the requirements that private landowners protect the floodway's conveyance 
capacity and elevate or otherwise protect structures to the 100year 
flood elevation. 
* Courts have supported technically based regulations adopted consistent 
with a federal, state, or local overall plan and standards (pollution controls 
or the National Flood Insurance Program, for example). 
Liability for Flood Damages 

In contrast with the small number of successful constitutional challenges 
to governmental floodplain management actions over the last 20 years, landowners 
have won thousands of damage suits against governmental units for 
causing or increasing flood damages. Most of these have been based on such 
common law grounds as nuisance or trespass. 

There have been more successful liability suits in recent years because 

* Large damage awards from juries (and subsequent payments of them 
by governments with "deep pockets") have made plaintiffs and lawyers 
more willing to litigate; 
* Courts have recognized broadened concepts of public and private landowner 
responsibility to other landowners and the public; 
* The "act of God" defense has diminished as a result of improved flood 
prediction capability and maps; 
* Improved data on stream flow and better hazard modeling have made 
proof of causation of the damages easier; 
* Improved technology,wider use of that technology, and adoption of 
regulations and guidelines have all raised the standard of "reasonable" 
actions on the part of government; and 
* The "sovereign immunity" defense of states and local governments, 
and to a lesser extent the federal government, has been modified by 
statutes and case law, making the governments responsible for more 
actions and their consequences. 
Avoiding Legal Problems 

There is little doubt that performance-oriented floodplain regulations 
(building codes, subdivision regulations, zoning, etc.) will continue to be 
upheld in the courts despite restrictions that may affect private property 
owners in some instances. Likewise, carefully crafted flood loss reduction 
measures will reduce community and state liability in the long run. It is 
important, however,that governments take care when formulating and 
implementing these measures to reduce potential legal problems and lessen 
the risk of constitutional challenge. 

AVOIDING LIABILITY FOR FLOOD 
DAMAGES 

There are many actionsthat state and local governments 
can take to reducetheir potential liabilityfor 
flood damages: 

* obtaining legal advice before taking anticipated 
actions; 

* adoptingcomprehensiveflood hazardplans, 
becausethey can avoid liability if they avoid 
flood hazards; 

* enrolling in the National Flood InsuranceProgram, 
becauselandownersare less likely to sue 
for damagesif they are insured and thus quickly 
receive compensation for their losses; 

* adoptingdrainageas well as flood hazard 
reductionplans and regulations (most suits against 
citiesforflood problems are reallyfor damages 
due to interference with natural drainage); 
* operating flood loss reduction measures 
(structures, warning systems) with greatercare 
to avoid claims of negligence; 

* avoidinghazardpronelocationsfor public
facilities;
* designingpublic works-roads, sewers, 
bridges,and water treatmentfacilities-to comply 
with federal, state, and localfloodplain 
guidelines and regulationsso they do not block 
Jloodflows or causedrainageproblems; 

* undertakingremedialflood loss reduction 
measuresfor existingfloodprone development, 
particularly wherethe problem has been partly 
the resultof government action; 
* purchasing liability insuranceand establishing 
self-insurancepools. 

M 

Between 1.916 and 1985, there were an average of 
about 100flood-related deaths annually; there is no 
indicationthat deaths are increasingor decreasing on 
a per capita basis. 

M 

Per capita flood damages were almost 2.5 times as 
great from 1951 to 1985 as they were from 1916 
through 1950, after adjusting for inflation. 

The natural and cultural resourcesoffloodplains are 
being lost at unacceptable rates. 

The Present and the Future 

Overview 

It is difficult to assess the effectiveness of floodplain management in the 
United States. The degree of accomlishment to date is impressive; at the same 
time, a considerable distance remains between the status quo and the ideal that 
can be envisioned. Two principal complications are that there are few clearly 
stated, measurable goals, and that there is not enough consistent, reliable 
data about program activities and their impacts to tell how much progress 
is being made in a given direction. 

Overall Effectiveness 

There is general agreement on three fronts: 

* Floodplain management should reduce the number of flood-related 
deaths in the nation. This goal has been partially achieved. Average 
annual loss of life from flooding has been somewhat reduced from the 
level that prevailed early in this century and has remained relatively 
constant for many years. 
* Floodplain management should result in an actual decline in the 
nation's flood losses, including public and private property damage, 
injuries, and disaster relief. This has not been achieved. In fact, there 
was a definite increase in flood damages from 1916 to 1985, although 
there is evidence that these losses have remained fairly constant over 
the last two decades when compared to broad economic indicators like 
the GNP. 
* Floodplain management should reduce the loss of the natural and cultural 
resources of the nation's floodplains. The programs designed to 
do this have not yet arrested that deterioration. 
Achievements to Date 

Several significant achievements in floodplain management can be noted, 
even though all the goals have not yet been reached. 

* There is now more widespread public recognition of flood hazards, the 
value of the cultural and natural resources of floodplains, and the close 
interrelationship of the hazards and the resources. 
* There is an extensive body of judicial decisions supporting floodplain 
management activities, indicating a perception throughout society that 
floodplain losses can and should be managed. 
* Numerous standards of terminology, procedures, performance, and 
quality have been developed, providing a uniform means of applying, 
reviewing, and evaluating the design, construction, and regulations 
needed for floodplain management, and also providing limited measures 
of effectiveness. 
* In many locales, floodplain development has been prevented or 
reduced in high hazard areas as a result of mapping and the establishmient 
and enforcement of regulations. 
* New development that meets commonly accepted flood-loss reduction 
standards has experienced greatly reduced losses. 
* The institutional framework for floodplain management has been 
improved through an expanded legislative base, new agencies, and supportive 
judicial interpretations. There has been a shift away from federal 
dominance toward a more equal partnership among federal, state, 
and local governments, and the private sector. 
* A considerable amount of floodplain acreage, particularly wetlands, 
has been preserved by both the public and private sectors. 

The Need for Specified Goals 

No single piece of legislation or other authority outlines a comprehensive 
set of measurable goals and objectives for floodplain management in 
the United States. Floodplain management would benefit from a set of specified 
goals meant to be achieved by a certain date and whose success can be 
measured. Numerous national goals have been proposed by various government 
agencies and observers of floodplain management. Some examples of 
these suggestions are managing the natural resources of floodplains in conjunction 
with loss reduction efforts by the year 2000; moving people out of 
areas where they arc continuously threatened by flooding; removing all residences 
and commercial establishments from the 20-year floodplain by the year 
2020 and restoring these lands to their natural state; reducing losses to existing 
buildings and infrastructure by requiring all federal agencies to assess the 
vulnerability to flooding of existing federal facilities and those state and local 
facilities constructed with federal aid; and reducing losses to areas and structures 
outside regulated floodplains. 

The Need for a Comprehensive Data Base 

There is a considerable amount of information about floodplain manage


ment available, but most of it was not collected with evaluation in mind; thus 

it is not precise enough to support judgments about the effectiveness of vari


ous floodplain management activities. This not only inhibits evaluation, but 

also hinders legislators, regulators, and other professionals in their efforts to 

establish, overhaul, or fine-tune programs and strategies to make them more 

effective. A more complete data base will also give local government leaders a 

better opportunity to identify the public risks and costs associated with flood


plain development. 

The obstacles to developing and maintaining an adequate data base are 

substantial. Important determinations must be made about the type of data 

to be collected, how often it should be collected, by whom, and using what 

criteria. Adequate funding must be found. 

Additional information should be developed on several important topics, 

including an examination of the full benefits and costs, both public and private, 
of floodplain occupancy; an evaluation of the monetary benefits of maintaining 
the natural uses of the floodplain; and a determination of the steps 
needed to reduce the potential losses in the areas of the nation with the 
highest risk of catastrophic impacts from flooding. 

The Effectiveness of Management 

Although a truly unified national program to manage floodplains is not 
yet in place, great strides have been made in that direction. The management 
framework has matured and expanded significantly since the 1960s. The 
growing recognition of the need for alternatives to federal investments in 
structural projects for flood loss reduction has been of particular importance. 

A major improvement was made in 1979, when protection of natural floodplain 
resources was formally embraced. But the conceptual approach presented 
in the current UnifiedNational ProgramforFloodplainManagementis still 
evolving. Further improvements could be made in the framework by developing 
a clear definition of' floodplain management and a set of measurable goals. 

Management efforts in general would be more effective if there were more 
flexibility for different approaches, smoother coordination among government 
agencies, and ways to account for local conditions. 

Allowing for Different Approaches 

Many floodplain losses are of a sort that simply cannot be addressed 
through a by-the-book approach. For example, management techniques for 
such high risk flood problems as ice jams, flash floods, coastal flooding and 
erosion, mudslides, ground failure, alluvial fans, fluctuating lake levels, move


able stream beds, and areas behind unsafe levees or below unsafe dams, are 

not included in most local programs, which are designed to meet standardized 
National Flood Insurance Program minimum criteria. New methods for identifying, 
mapping, and regulating areas with these flood hazards have been 
developed in some states-particularly in the arid West-through special 

GISs AND THE FLOODPLAIN
MANAGEMENT DATA BASE


Itsent advancesin tle developmentanrdapplication 

qfgeographz in!firmnationsi1sternscan inprol e t/l 
fioodpklin tnanageznentdata base. W ith thete sys 
lerli,.,lavets of in/frma/ion, iuch as that from flood 
insurane rnap.s,cultutal resourcemaps, and tle 
TIGER data svstem of the U S. Cernsus Bueau, 
can be6 n hoined fordisplay, analyt1s,and tanangemientapplications. 



AGENCY AND ORGANIZATION
COORDINATION


Positive interagency coordination is exemplified by 
profissional groups like the Association of State 

Floodplain Managers and the Association of State 

Dam Safety Officials, and bodies like the Inter


agencyCommittee on Dam Safety. Federal, state, 

and local officials, and representatives of the private 

sector form the memberships of these groups, and they 

have brought an important spirit of cooperation and 

coordination that has been of tremendous benefit to 

7nlodplainmanagementover the past decade. They 
mreet formallly once a year and coordinate throughout 
the year through subcommittee work and special 
projects. 

cooperative efforts with the Federal Emergency Management Agency. This 
sort of flexible and innovative approach yields more effective management 
in the long run. Incentives for communities to map and regulate high risk 
hazard areas are now being provided through the Community Rating System 
of the National Flood Insurance Program. 

Another reason that management flexibility is needed is that the conditions 
that cause floods do not recognize the political boundaries by which most 
floodplain management techniques are applied. Many professionals believe 
that comprehensive management based on hydrologic units must be made a 
higher priority, especially if natural resources are to be protected. The river 
basin commissions, the Environmental Protection Agency's National Estuarine 
Sanctuary Program, and the National Park Service's State and Local 
River Conservation Program are examples of this technique. To facilitate 
broader management, the states could enact legislation providing for regional 
or watershed management, for river corridor management, and for other 
regional efforts based on hydrologic and other natural boundaries rather than 
political jurisdictions. 

Coordination among Government Agencies 

There is more coordination and better cooperation among all levels of 
government now than there was 25 years ago, but improvements could still be 
made. Each government agency involved with floodplain management has its 
own legislative mandate and in general, each has been diligent in carrying out 
that mandate within the imposed statutory limits. From the standpoint of an 
overall federal program for floodplain management, however, there are many 
inconsistencies of purpose and procedure, overlaps, gaps, and conflicts. Some 
of the inconsistencies can be reduced or eliminated by administrative action, 
but some conflicts result simply from differing attitudes and expectations 
about the ultimate responsibility and commitment of resources to respond 
to flood problems, and these are not likely to be readily resolved. Nevertheless, 
a spirit of cooperation and common purpose can smooth many conflicts 
and enhance existing efforts. 

Providing for Local Conditions 

Prescribing uniform national standards for the preservation, use, and 
development of floodplains and other hazard areas for application at the local 
level can be inefficient and result in social inequities. Many of the existing 
floodplain management tools are more easily applied in communities with 
fairly high standards of living, where the local government has adequate staff, 
resources, and expertise. This excludes many small rural communities and 
economically disadvantaged areas. Natural resource preservation is a bottom 
priority in low-income communities where a resident cannot even count on 
the availability of potable water or sanitary facilities during and after a flood. 
An awareness of local conditions could be incorporated into the national program 
through wider use of' performance standards, provisions of the Community 
Rating System of the National Flood Insurance Program, and more flexibility 
in the application of requirements for a positive benefit/cost ratio for 
federal funding of flood control projects. 


The Effectiveness of
Floodplain Management Strategies and Tools


Additional accomplishments could be achieved through better or more 

extensive use of the strategies and tools of floodplain management. Of the 

four strategies, modifying flooding has traditionally been the most popular 

because most of the planning, funding, construction, and implementation 

for structural measures is carried out by the state or federal government, 

and because local and individual adjustments or sacrifices are minimal. In 

contrast, many measures to modify susceptibility to flood damages or to 

modify the impacts of flooding are implemented on a structure-by-structure 

or property-by-property basis and require constant vigilance, personal inconvenience, 
and financial sacrifice. These drawbacks resulted in a lack of public 
support for such measures in the past, and consequently local governments 
were often reluctant to impose or enforce them. By the mid-1980s, however, 
this impediment had been largely overcome and local officials began to focus 
on how to comply with federal and state requirements and administer community 
programs to manage floodplains. Measures to modify susceptibility 
to flood damage and disruption and to modify the impacts of flooding are 
now widely accepted, even though some communities still have difficulty 
administering them. The strategy of restoring and preserving the natural 
and cultural resources of floodplains has had little exposure to date and 
needs to be better integrated with the other strategies, both conceptually 
and in practice. 

Modifying Susceptibility to Flood Damage and Disruption 

The tools used for this strategy have enjoyed widespread, fairly successful 

implementation. Susceptibility to flooding in the United States is constantly 
being effectively lessened at individual and local levels through the use of' regulations, 
development policies, programs for disaster preparedness and assistance, 

and warning systems. Evidence indicates, however, that overall vulnerability 
has either increased or stayed the same, probably because of the large amount 
of vulnerable development already in place, numerous exceptions to the state 
and local policies that would reduce that development, and the fact that population 
growth, movement, and urbanization sometimes take place so quickly 
or in such unexpected ways that adequate planning and regulation simply 
cannot be established soon enough to prevent unwise use of floodplain areas. 
This strategy may have the most potential for widespread future use, however, 
because its tools can be coordinated well with other strategies and because it 
provides an ongoing, more enduring way of adjusting to the flood hazard-
that is, altering human behavior usually before the losses occur. 

Improvements could be made in the implementation of this strategy by 

* improving the enforcement of floodplain regulations by local
governments;
* reducing the usually unfounded concern of local and state officials that 
strict floodplain regulations will be challenged as unconstitutional takings 
of private property; 

* minimizing flood damage to existing infrastructure and properly 
designing and regulating future infrastructure that must be located in 
or near the floodplain; and 
* ensuring that current disaster assistance policies do not undermine 
long-range floodplain management efforts. 
Modifying Flooding 

National efforts to modify flooding have probably been more successful 
than those directed toward any other strategy. The approach of controlling 
floods is older than the other strategies, and over the course of five or six 
decades countless floodprone situations have been alleviated with structural 
measures. 

There is increasing recognition that the strategy of modifying flooding 
can be counterproductive in at least two ways. First, it has been suggested 
that the creation of structural protective works encourages development in the 

REDUCING LOSSES THROUGH
WARNING SYSTEMS


Annual flood damagesin the ConnecticutRiver 
Basin were reduced by $750,000 with a flood 
warning system that cost about $250,000 annually. 

FLOOD CONTROL INVESTMENT
AND RETURN


The federalgovernmentspent over$13 billionfor 

dams and other flood controlstructures between 

1936 and 1975. About $360 million had been 
expendedon shorelineprotectionitudiesand projects 

by 1985. In return ]br these investments, billionsof 

dollarsin property damagehave been avoided and 
hundredsof thousandsof people have beenprotected 
from anxiety, injury, and death. 


THE EXTENT OF THE NFIP 

1s o/ 1990, 82 o/ thnnotion 2'()s (0 /0oorpronc 

comiSinivtirshad CoinedtheNationalFlloodInsII


onceProgram /I 1990) 2'J9mtillioolmnd inmii


oncepolifics if fre inI lorur,piiroidim over 92(00))il-

lionin cOverage. From 1 978 to 1989, over,8 ,)000 

floodrknitrne oaimshabdbeen paid, IotallihnSabout
$3. I billion.


PROTECTING RIVERS FROM 
ALTERATION 

A. qf1990, .9.251 miles on 123of tbe nations 
rivershad beend&esinated
as witld or scenic, and 
there/oreprotectedunderfideral t i. But the'seprotectedstretchesare 
greatlyoutnumberedby the stream 

egmrentstbat ivould be alteredby proposeddaos, 
vhannelmodi/ications, ane!otherprojectIs. 

"protected" area, resulting in increased vulnerability, perhaps not to the 

design flood, but to larger ones or to unforeseen catastrophic events like struc


tural failure. Second, structural measures can have adverse impacts on wildlife 

habitat, scenic resources, and water quality, thus undercutting other flood


plain management strategies.
Partly as a result of these concerns, there has been a considerable shift


away from reliance on structural solutions since the early 1960s. The planning

and installation of measures to modify floods, however,have not been aban


doned. Flood control projects are still needed to complement the application

of other floodplain management strategies, particularly to protect existing 

development. 

There is an opportunity now to reformulate this strategy to acknowl


edge its relationship to other techniques. Some of the tools to implement this 

strategy, such as land treatment measures, on-site detention, and shoreline 

protection, can be important components of comprehensive floodplain 

management and resource protection programs. 

Modifying the Impact of Flooding on 

Individuals and the Community 

The impacts of flooding on individuals and communities have definitely 

been modified over the last 25 years, largely through increased awareness of 

flood hazards as a result of the provision of information and education, and 

because of the availability of flood insurance. After many years of counter


productive effects, two of the tools for this strategy have recently undergone

basic revisions that may make them more effectiveat reducing future losses: 

tax adjustments for flood losses have been reduced, and postflood recovery 

measures designed to minimize future losses have been determined to be 

an appropriate use of disaster assistance funds. 

The implementation of this strategy could be improved by 

* expanding individual awareness of and knowledgeabout floodplains; 
* improving training programs for code administrators, planners, inspectors, 
public works directors, and other local government personnel 
directly involved in floodplain management; 
* enlarging the premium base by increasing the number of insured 
structures, and thereby moving the National Flood Insurance Program 
closer to a fully actuarial basis; and 
* ensuring that postdisaster mitigation funds are used completely and 
creatively. 
Restoring and Preserving the Natural and Cultural 
Resourcesof Floodplains 

As the latest addition to the array of floodplain management strategies 

and the one least well-integrated with the others, it is not surprising that this 
strategy has met with limited success. Floodplain land is being preserved in 
a limited way through acquisition, public understanding and support for preservation 
and restoration of natural resources is growing, and mapping of the 

nation's wetlands is more than half finished. These accomplishments, however, 
have been the result largely of programs, policies, and efforts outside 
the floodplain management arena. Regulations to protect and manage natural 
resources in general are not well coordinated with those to reduce flood losses, 
resulting in conflicts when implementation and enforcement are at stake. The 
strategy itself needs to be better integrated both with other floodplain managemcnt 
tools and strategies and with compatible efforts in other fields, such as 
river corridor management, endangered species protection, and nonpoint 
pollution control programs. 


INTEGRATING FLOOD LOSS 

REDUCTION AND NATURAL 

RESOURCE PROTECTION 

Most local flood loss reductionprogramsfocus 

primarily on the IOO-yearfloodplain, while natural 

resourceprotectionprogramsfocus on aparticular 

resource(wetlands, fior example) which may or may 

/4. a_ notf be located i Ace{>T#& in tlie'floodplain. The two types of 

__ God:am S | o@Jw~programsalso are triggeredby differentevents. Dis


_ aster relief is provided after a flood; a section404 

permit is requiredwhen dredgingor filling is 

planned; a wild and scenicriver study begins after 

Congressionalaction. These basic dizffrencesmake, 

inkgration of the programsdifficult. 

The restorationand preservationoffloodplains as natural resourcesis largely the result of efforts that are not
well coordinated with theprincipalprogramsoffloodplain management.


Floodplain,WildcatFalls,JoyceKilmerMemorialForest,NorthCarolina. 

Conclusion 

Over the past 25 years, floodplain management has matured fromna focus on 
reducing flood losses by using structural measures to a broader approach that 
incorporates structural and nonstructural measures for flood loss reduction 
and also takes into consideration the protection of the natural and cultural 
resources of floodplains. The examples of flood damages averted, lives saved, 
and resources preserved are plentiful. It is evident that substantial progress 
has been made, and that diligent work is underway to remedy past shortcomings 
and reach even greater levels of achievement. 

If current trends continue, the near future will see a further broadening 
of the scope of floodplain management to encompass such activities as storm-

water management, greenway and river corridor management, and watershed 
management. Further integration of individual strategies and tools is likely, so 
that a more unified floodplain management program can emerge, with fewer 
conflicts among goals and activities. Technological advances also promise the 

improved application of existing strategies and tools. 

A number of important opportunities are emerging for improving the 
future effectiveness of floodplain management in the United States. This 
report on the nation's floodplain management activities-the first comprehensive 
assessment in over 25 years-has identified a plethora of actions to 
be pursued if significant improvements are to be made in floodplain management 
in the coming decade. Of these, two stand paramount: a simplification 
of the concept of floodplain management, and a set of specific national goals 
with a timetable for their achievement. These two needs should be addressed 

as the Federal Interagency Floodplain Managment Task Force undertakes to 
further refine the Unfied NationalProgramfor FloodplainManagetment. 


RETROSPECT AND PROSPECT


-an invited comment by Gilbert F White 

This Assessment is unprecedented in its depth of analysis of the nature and 
effectiveness of the nation's management of floodplains. It is the most detailed 
and nearly comprehensive of all studies of those matters since the concept of 
floodplain management took official root in the mid-1960s. It places that concept 
in a broader context than ever before, and it provides a base for launching 
a series of steps to assure that local and state as well as federal programs 
can at last approach the aspirations that have evolved over the past 65 years. 

That evolutionary process has been reflected in a stream of laws, executive 
orders, regulations, new groups, and reports. Debate over the wisdom of reliance 
on simple levees and channel modifications began in the wake of the 
1927 flood on the Lower Mississippi. It widened to include issues of dams and 
economic justification after the Ohio River floods of 1936 and 1938 and a 
concurrent upstream versus downstream controversy over land treatment. By 
1966 a still broader view of the potential role of nonstructural measures found 
favor. Then followed a series of revisions and expansions of federal and state 
activities. Those included the National Flood Insurance Act of 1968, a 
National Science Foundation appraisal of flood research in 1977, a Unified 
National Program for Floodplain Management in 1976, with revisions in 1979 and 
1986, three Executive Orders, a formal linkage with emergency management 
programs, and the organization of vigorous nongovernment groups such as 
the Association of State Floodplain Managers and the Association of State 
Wetland Managers. All of this and much more is examined in the Assessment. 
To sum up, the report tells the country what has been happening in 
floodplain management; how well or how poorly the responsible federal and 
state agencies have been doing; and what are promising means of improving 
the prospect. The result is the first thorough appraisal of ambiguous national 
aims and how those compare with the present situation on the lands at risk-
the diverse areas of watercourses, adjacent wetlands, and the shores of 
streams, lakes, and oceans. 

The report candidly recognizes the severe handicaps of incomplete and 
inconsistent collection of data on which policy judgments must be based. The 
data base is the- one need specified in the 1966 House Document on which 
almost no action has been taken. 

For other needs, the record of change has been diverse but generally positive. 
In no instance, however, has achievement matched the hopes of earlier 
years. The definition of precisely what is meant by floodplain management in 
particular areas of the country or under the jurisdiction of specific agencies is 
still far from clear or uniform in either principle or practice. The policy goals 
for the sustainable use of floodplains have progressed in agency thinking but 
are proving difficult to meet in operation in the field. It has not been made 
clear how floodplain use is inseparably linked to the maintenance of natural 
resources for the common good for the foreseeable future. The effectiveness of 
individual federal and state programs, each with a different statutory 
authority, suffers thereby. 

Cooperation among the administrators of federal programs, while generally 
cordial and helpful, has not yet yielded a genuinely unified effort. Lacking 
exemplary effectiveness at that level, state and local agencies cannot be 
expected to act in concord in meeting national goals. 

Great gains have been made in public information and education. Far more 
legislators, administrators, business executives, farmers, householders, and 
school children are aware of flood hazards than a decade ago. The level and 
quality of information, however, still is far below what would be required to 
induce effective action in the event of a threatening flood, and even more so 
in the days when measures are needed to mitigate future emergencies. 

Flood forecasting precision has generally improved. The demonstrated 
ability of communities to respond positively to a warning is less certain and 
is uneven. 


The report suggests lines along which improvement can be brought about 
and recommends consideration of a number of changes in policy and procedure. 
The report's Review Committee does likewise with its Action Agenda for 
Managingthe Nation'sFloodplains.These must be examined now against the background 
of experience with previous statements of optimal floodplain policy, 
such as House Document 465 or the Unified National Programfor Floodplain 
Management.Only fragments of those proposals were adopted. Can anything be 
learned from the conditions that either promoted or blocked them? What are 
the factors in climate of public opinion and in government organization that 
worked for or against them at that time and that may have changed 
subsequently? 

It is evident that the reconciliation of thinking among professional groups, 
for example, has been advanced by research, conferences, training, and publications. 
Hydrologists, engineers, geographers, economists, land planners, 
ecologists, city managers, insurance executives, and disaster relief directors, 
among others, now arc speaking the same language. But there are at least 
three directions in which lessons learned arc still not practiced. 

One important lesson is that quick and nation-wide change in procedures 
without careful trial in selected areas and without subsequent critical 
appraisal can be counter-productive. When the Tennessee Valley Authority 
established its community assistance program for flood damage prevention 
planning in 1953 and the Corps of Engineers introduced its floodplain 
management services program in 1960, they moved cautiously and employed 
a variety of trial approaches. In contrast, when national flood insurance was 
introduced in 1968 there was a brave commitment to offer coverage to all 
parts of the country at once. Little attention was given to post-audits of the 
rates, terms of insurance, map adequacy, and relation of detailed regulations 
to local physical and social conditions. As a result, the Federal Insurance 
Administration found itself locked into sometimes unwieldy or ineffective 
procedures that might well have been avoided in the light of experimentation. 
The attempt in the late 1970s to set up a nation-wide floodplain map file was 
likewisean unfortunately hasty enterprise. In its 23 years of operations, the 
National Flood Insurance Program has achieved much and continues to gain 
new experience. The current implementation of the Community Rating System 
now offers special opportunities to appraise the suitability of national 
standards and procedures at the local level.As new improvements are made 
in federal programs, it will be important to craft them on an experimental 
basis with careful provision for evaluation as they are launched. 

A second lesson derives from the contrast over the years between expressions 
of desirable unified policy and measures to, in practice, unify the activities 
of agencies which in theory subscribe to the policy. There has been neither 
a single statement of Congressional intent with respect to floodplain 
management similar to the Earthquake Hazards Reduction Act of 1977, nor a 
delegation to a single executive agency of responsibility for coordination of the 
various federal programs. The Bureau of the Budget was interested in such 
coordination in the mid-1960s but did not take a strong hand. The Water 
Resources Council served as a meeting place of interested agencies without 
having statutory authority. After the council disbanded in 1982 it was followed 
by the Interagency Task Force, a voluntary group that also lacked authority to 
enforce desirable action as outlined in three Executive Orders. It cannot be 
expected that conscientious administrators will abandon their own statutory 
authority and responsibility before joining cooperative ventures, no matter 
how desirable the goals. It is just as clear that unless a strong statement is 
made by the Congress on the ways in which the basic policies of the individual 
federal agencies are to be related to the underlying aims in managing 
floodplain resources, those policies will have little significance in the field, 
where they influence or are constrained by state and local practices. 

The third major lesson is that floodplain policy changes must be taken in 
the context of broad environmental goals applied to local conditions. This was 
the case in the unfolding of the Coastal Zone Management Act where four 
federal agencies have joined in a partnership for action on habitat protection, 
nonpoint source pollution management, and sediment control. It occurs in 
the implementation of soil conservation programs on lands where environ



mental integrity must harmonize with economic considerations. It is acutely 
the case in the delineation of wetlands, where the rigidity of proposed national 
criteria confronts wide variety in interpretation of suitable floodplain use. 
Coastal erosion raises similar issues. The reconciliation of multiple and sometimes 
inconsistent national goals is an endemic problem in resource management. 
It can only be achieved effectively by dealing with particular landscapes 
in particular regions. When national goals shift or are clarified, as they surely 
will, the complexity increases. Unless floodplain management practices take 
into account local food and fiber production, biota, water supply, urban land 
use, recreation, and more-in addition to flood loss reduction-the goals for 
maintaining the sustainability of floodplains will surely not be met. 

Experience over the past 25 years suggests that to help achieve the improvements 
in prospect will require a willingness to test and appraise new programs, 
a Congressional definition of unified federal policy, an executive decision 
to assure the coordination of the federal agencies, and a commitment by 
representatives of the principal state, local, and nongovernment groups to collaborate 
in adapting national aims to local conditions where the benefits will 
be seen-on the borders of the nation's rivers, lakes, and coasts. Without 
these measures, the resources of those areas will remain unduly vulnerable to 
natural extremes in stream flows and tides, and the people of this nation will 
receive less than optimal benefits from floodplains' amenities, soil, water, and 
biota. 

GilbertE White has been observing the nation's floodplains for over 50years. He is a Distinguished 
Service Professor Emeritus of Geography and the founder and former director of the Natural Hazards 
Researchand Applications Infl)rmathfn Center at the University of Colorado. He was chair of the disk 
Force on Federal Flood Control Policy, 1965-66, and qf the National Review Committee established in 
1989 to assist in carrying out the assessment summarized in this volume. 


Photo Credits: 

Cox=Bob Cox, Floodplain ManagemnentSection, Louisiana I)epartment of Transiportation and Development 
Corps=UJS.Army CorpsofEngineers 
ELA=US EnvironmentalProtectionAeency 

TVA=Tnnessee Valky Authority 
FEMA=FederalEmergencyManagementAgency 
NHRAI(=Natural HazardsResearchand ApplicationsInformationCenter 

the photographrcreditedto the TVA 
the ''VA for presentationsby that agency. Whereverpossibk, additional creditis given; in some cases, however, 
the original donorcould not be datermined. 

Note: Many tf were originatlyprovided by otherfederaland state agenciesto 

p. 7 JohnMcShane FIEMA;pp 9-10 (all photos),Cox;p. I/ (top nigh), EPA; p.11 (bottomright),
MerrijmakRiver WatershedCouncil,p.]] (kft), Cox;p.12 (rightand bottomkeft),Cox;p.12 (top k14),
NHRAI(', p.13 (top), ColoradoDepartmentjf DisasterEmnergency p.13 (bottom),TVA/Arizona

Services; 

Departmentof WaterResources;p. 14, (top), Cox;p. 14 (middle),Corps;p.14 (bottom),' VA/SouthCarolina 
WaterResourcesCommission;p.15 (right), T'VA/CaliforniaDepartmentof WaterResources,p.15 (lefi),
7'VA/WashingtonStateDepartmentof Ecology,p. 16, Corps;p. 17 (left and rigeht), Corps;p.18 (top), 

NHRAIC' p. 18 (middle),Cox,p.18 (bottom),TVA/MassachusettsDivisionof WaterResources,p l9 (top),

TVA, p. 19 (bottom),TVA/IPA, p.20 (top ri4ght),Cox;p. 20 (top kfi), TVA/Mavsachusetts Divisionof 
WaterResources;p 20 (bottom l.ft),Cox;p 21 (lop right), Cox,p 21 (bottomriTht),EPA; p. 23, 
TVA/Corps;p.24 (bothphotos),NHRAIC/Corps-PittsburghOffice;p 26, Cox;p34, Corps-Vicksburq

Offie;
p.35,Corps-Vicksburg

Office,p 37 Corps;p.38, 'IVA/UtahDepartmentof PublucSafety;p.39, TVA 
/MassarhusettsDivisionof Water Resources;p. 40, NHRAIC; p.43 (top), Corps,p.43 (bottom), TVA/UlijhDepartmentof PublicSeafety;p 44, Cox;p.45, EPA; p.47 Corps;p 48, TVA; p.51, Corps;p.52, FEMA; 

p.55 (top), Cox; p 55 (bottom), TVA/Texas WaterCommission;p56, FFMA, p65, Cox. 
Back cover. 
Illustrationofsornefloodconsequences

and 
floodplain mianagerneflrrd

wasures. Clock-wisefrom top: 

1. Floodwaterdetention.2. Regulations and development 
po/icies.3. Information.4. Coastalprotection.5. Flood 
em.rgencyteasure. 6. Naturalprotectionysterms. 
7 Preservingnaturalresources.8. Mappingflood 
ha2ardaras. 9. Structural elevation. 


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FIA-1 7/ May 1992