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OCR for page 58
3
The Federal Role in Beach Nourishment
This chapter introduces the federal agencies concerned with shore protec-
tion, especially as it involves beach nourishment. The roles of five agencies are
specifically described, and the accreditation of beach nourishment for insurance
purposes is explored.
The federal government is involved in coastal management and coastal haz-
ard reduction through a variety of programs that are primarily carried out by three
agencies: the U.S. Army Corps of Engineers (USAGE), the Federal Emergency
Management Agency (FEMA), and the National Oceanic and Atmospheric Ad-
ministration (NOAA). Two other agencies, the U.S. Geological Survey (USGS)
and the Minerals Management Service (MMS), have smaller but significant roles
in beach nourishment issues. The degree to which these agencies should sub-
scribe to or use beach nourishment to stabilize or protect beachfront communities
is an unresolved question. The answer may vary among the agencies, depending
on how they define or envision successful achievement of their missions: to
prevent and mitigate storm damage, manage coastal resources effectively for the
long term, and enhance a recreational beach and the local recreational economy.
THE U.S. ARMY CORPS OF ENGINEERS
The USACE is the agency designated by Congress to protect the nation's
shores from the chronic effects of erosion and coastal flooding. The USAGE's
shore protection role is an extension of its longstanding civil works mission. In
response to a request from the state of New Jersey for beach erosion control
assistance in 1930, Congress enacted Public Law 71-520, which authorized the
58
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THE FEDERAL ROLE IN BEACH NOURISHMENT
59
USACE to undertake comprehensive shore erosion studies in cooperation with
state agencies. As a result, the Beach Erosion Board (BEB) was created to ad-
dress more thoroughly the growing problems of beach erosion and storm damage
that were threatening the prosperous new beach recreation tourist industry. The
BEB's early efforts to protect beaches relied mostly on constructing groins to trap
sand and constructing bulkheads to halt erosion. However, research in the 1930s
suggested that any fixed line of defense against waves should have a reasonable
expanse of sand in front. "In the 1940s, the BEB urged local interests to construct
projects large enough to protect areas extending headland to headland or inlet to
inlet and recommended artificial nourishment of the beach" (USAGE, 1991~.
Until the late 1940s, the assistance provided by the federal government through
the USACE was primarily of a planning or technical advisory nature in the
development of beach erosion control projects. The most common practice for
controlling beach erosion at that time was construction of hard structures such as
jetties, groins, and seawalls. In many older beach resort communities, such as
Atlantic City, Miami Beach, and Ocean City, Maryland, extensive groin fields
were constructed as the accepted means to halt loss of the beach. This approach
was relatively successful then because the coast did not have nearly the extent of
development it has now. The solution to an erosion problem along a short length
of coast may have been a hard structure, even though it often moved the problem
to an undeveloped downdrift beach area.
Following World War II, society turned more and more to beaches for recre-
ational opportunities, resulting in community growth along the nation's shores.
This trend has continued and has accelerated since the 1970s (Culliton et al.,
1990~. The proliferation of beachfront residences, often constructed where the
primary dune had once been, resulted in more demand for erosion relief from the
federal government. In response, the USAGE's approach to beach erosion shifted
away from hard structures and toward the replenishment of sand that had been
lost along the beachfronts of resort communities. Coastal engineers began to
recognize, and imitate, in their beach erosion control designs the natural protec-
tive features of a wide berm and fronting primary dune (USAGE, 1994~. The
BEB was replaced in 1963 by the Coastal Engineering Research Board (CERB)
and the Coastal Engineering Research Center (CERC). Both organizations con-
tinue today. The CERB's research initiatives are carried out by the CERC
(Holmes, 1993~. The increasing body of knowledge and continuing refinement of
the science and practice of coastal engineering resulting from university and
USACE research have improved both our understanding and the quantification of
the forces that affect beach size and shape and the changes that beaches undergo.
In turn, our ability to predict sediment behavior on beaches and therefore to
design successful beach fill projects has improved considerably in the past two
decades.
The USACE conducts beach erosion control work under several different
authorities. Under one of these, Section 111 of the River and Harbor Act of 1968,
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60
BEACHNOURISHMENT AND PROTECTION
mitigation can be undertaken for detrimental erosion or accretion that results
from federal navigational works. For example, the 1993 beach fill at Folly Beach,
South Carolina, was constructed under this authority because it was determined
that stabilization of the Charleston Harbor entrance channel by jetties was in-
creasing erosion at this downdrift location. Another authority is legislation to
initiate site-specific studies and projects proposed as a part of biennial public
works authorization bills. If approved, these studies and projects follow a multi-
year investigation prior to implementation of nourishment.
Presently, the USACE places sand on beaches via two distinctly different
initiatives. The first is site-specific beach nourishment projects that are the prod-
uct of congressional authorization and involve lengthy planning, design, and
construction elements. The analysis and engineering for this type of work may be
conducted by the local USACE district office; the Dade County, Florida, and
Ocean City, Maryland, projects are examples. The other option is the placement
of beach-quality material from the construction or maintenance of navigation
projects, generally from the dredging of inlets, channel, and harbors. Such place-
ment under current procedures is the addition of sand to the beach system and is
not an element of a designed beach nourishment project, although the placement
location may also be the site of an authorized beach nourishment project. The
sand that is supplied to the beach may be compatible with the sedimentary sys-
tem, but it may not have the size or weight that will ensure long residence in the
system.
The case studies reviewed by the committee (see Appendix B) indicate the
degree of investigation and design that the USACE is currently conducting in the
construction of beach nourishment projects. The USACE believes that nourish-
ment is usually the most cost-effective way to reduce the threat of coastal storm
damage and avoid the high costs of severe coastal storm damage.
The design of federal shore protection projects by the USACE follows the
concept of the optimization of net benefits accrued rather than a defense against
storm hazards associated with a specific hazard benchmark. The required eco-
nomic optimization is related to a set of design storms to evaluate the cost effec-
tiveness of design alternatives. Designers prepare a planform that will protect
either the buildings behind the dune line or the shore protection structures from
damage from a storm meeting these criteria. The defined events are chosen to
reflect realistic combinations of the various parameters that are descriptive of
historic storms that have impacted the location of interest. For tropical storms, the
storm should encompass the range of durations, maximum winds, radius to maxi-
mum winds, pressure deficits, track, etc., that have impacted the area. For extra-
tropical storms (northeasters), duration, stage hydrograph, and maximum wind
speeds are appropriate descriptors. Frequency relationships are then assigned to
the set of storms and their damages. Storm criteria vary substantially among
projects.
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THE FEDERAL ROLE IN BEACH NOURISHMENT
THE NATIONAL OCEANIC AND
ATMOSPHERIC ADMINISTRATION
61
The upsurge in development along our nation's shores in the 1950s and
1960s prompted the federal government to initiate action to protect the shores
from the environmentally damaging effects of development. These effects re-
sulted from improper construction standards for high-hazard zones and improper
location of construction (such as the placement of buildings in the primary-dune
zone), which caused numerous and costly property losses and casualties from
severe coastal storms. The Ash Wednesday storm of 1962 that devastated much
of the eastern seaboard is an example of the kind of shore protection problem that
was developing when the new coastal communities were exposed to the meteoro-
logical rarity that hits the coast perhaps only once or twice a century (Podufaly,
1962).
The Coastal Zone Management Act (CZMA) was signed into law in 1972. It
established a national program to assist the states in comprehensively managing
the nation's precious coastal resources through wise management practices.
NOAA administers the CZMA through a partnership with coastal states that elect
to participate. Currently, 24 coastal states and 5 island territories have developed
federally approved coastal zone management programs. They involve 94 percent
of the nation's 150,000 km of shoreline (Department of Commerce, 1994~.
Among the programmatic elements that the CZMA identified as important is
coastal hazard reduction. In its 1994 Biennial Report to Congress on the Admin-
istration of the Coastal Zone Management Act, NOAA (1994) stated:
The CZMA declares a national policy for minimizing the loss of life and prop-
erty caused by inappropriate development in areas prone to erosion and coastal
flooding. NOAA seeks to achieve this goal through state coastal management
programs, and has placed increasing emphasis on improvements in this area
through the Coastal Zone Enhancement Program. NOAA assists states with
technical assistance in the area of coastal hazards through various activities,
including participation on mitigation teams, information sharing, and, in limited
cases, by using discretionary funding to conduct post-storm research for use in
coastal hazard planning efforts.
It went on to say:
NOAA assists state efforts in coastal hazards planning and mitigation by work-
ing with the FEMA on post-hazard mitigation teams, and exercising its respon-
sibilities with other federal agencies. Interagency Hazard Mitigation Teams
identify and evaluate areas having significant hazards; review existing land-use
regulations, building codes/construction standards, communications and utili-
ties networks, and existing hazard-mitigation programs and authorities; recom-
mend actions to prevent damage from future events; and coordinate actions to
implement the team's recommendations.
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62
BEACH NOURISHMENT AND PROTECTION
The federal role in coastal management involves NOAA working closely
with states to solve their coastal hazard problems. NOAA has identified im-
proved land-use planning as well as appropriate construction siting and design as
the most effective means to mitigate erosion and coastal storm hazards. However,
although 24 states and territories (90 percent of the participants in the Coastal
Zone Management Plan) identified coastal hazards as a priority for coastal man-
agement enhancements, only two states reported on in the 1992-1993 CZMA
biennial report include coastal engineering projects as part of their coastal man-
agement improvements. It is important to remember that NOAA's management
initiative is achieved through approved state activities.
THE FEDERAL EMERGENCY MANAGEMENT AGENCY
FEMA is responsible for coordinating planning and response activities aris-
ing from all types of disasters (see Box 3-1). Such disasters include coastal
hurricanes, extratropical storms, tsunamis, and damage from northeasters (i.e.,
coastal storms along the U.S. East coast), which can devastate low-lying coastal
communities. FEMA works with state and local governments to develop disaster
mitigation and response strategies, assists state and local governments following
a disaster by assisting in damage and needs assessments and in immediate re-
sponse, urges improved mitigation of potential hazard losses through projects and
programs, and manages the National Flood Insurance Program (NFIP). FEMA
reorganized in 1994 and formed four new management initiatives: (1) mitigation;
(2) preparedness, training, and exercise; (3) response and recovery; and (4) op-
erations support. The mitigation mission and FEMA's role in the NFIP are dis
cussed below.
Along with traditional FEMA mitigation activities, such as improvement of
construction quality and moving buildings out of a floodway, the questions ad-
dressed in this report are the mitigation potential of beach nourishment and the
ability to quantify the mitigation benefit, the proper level of credit that these
benefits receive within FEMA programs, and FEMA's appropriate level of par-
ticipation in beach nourishment as a mitigation activity. FEMA has always con-
sidered a wide variety of cost-effective mitigation techniques, with an emphasis
on nonstructural techniques. Because there are many widely varying uncertain-
ties associated with beach nourishment project design and prediction (see Table
4-1, for example), accurate protection levels and mitigation benefits resulting
from a project are difficult to determine. Beach nourishment offers coastal hazard
mitigation benefits (see Box 3-2) in addition to other activities, such as improved
construction standards and retrofitting old construction, activities that FEMA has
promoted in beach areas. Erosion of a beach is addressed directly by the replace-
ment of sediment lost from the beach and by placing fill so that the shoreline is
advanced seaward. The beach erosion process is moved back in time so that an
earlier sequence of shoreline change can be repeated (O'Brien, 1985), thus miti
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THE FEDERAL ROLE IN BEACH NOURISHMENT
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63
Sating the erosion hazard to coastal communities. Additionally, storm wave en-
ergy is dissipated on the beach rather than on or in close proximity to the founda-
tions of shorefront buildings. The dissipation of energy seaward of the construc-
tion setback lines also lessens the velocity of wave runup, which can attack
building foundations. Whether, to what degree, or how the NFIP should recog
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64
= . .....
BEaCH NOURISHMENT AND PROTECTION
nize these hazard reduction benefits has stimulated considerable public and con-
gressional debate. The technical basis for decision making on these issues is
discussed below.
The National Flood Insurance Program
Program Overview
The NFIP is both a financial protection and a hazard mitigation program. It
extends and provides benefits to entire populations residing in coastal floodplains
as well as to floodplains in interior regions of the country. Federally underwritten
flood insurance is available (within prescribed limits) at a reasonable cost for
buildings in floodplains for which privately underwritten insurance would either
be unavailable or not affordable by most residents. Financial protection is pro-
vided in the form of flood insurance for homeowners and businesses located in
interior and coastal hazard-prone areas. FEMA conducts detailed surveys of flood-
plains to determine levels of hazard. The hazards are then designated flood haz-
ard zones on floodplain area maps. The objective of the hazard mitigation compo-
nent is to improve structural integrity and survivability against anticipated
flood-related damage. For structures to qualify for federally backed flood insur-
ance, community zoning laws must meet certain requirements, and new and
rebuilt structures must be designed and constructed in accordance with standards
that are appropriate to the hazard zone in which a structure is located (see Box
3-31.
For nourishment projects to be considered for possible benefits under the
NFIP, a level of protection needs to be established. FEMA and other interested
agencies must have quantified information regarding the level of protection that
will be provided by the project. In the process of risk assessment and reduction
associated with beachfront construction, it is imperative that the extremes of
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THE FEDERAL ROLE IN BEACH NOURISHMENT
65
physical forces be quantifiable, including the likelihood of various extreme com-
binations of storm waves, tides, and storm surge, and that the resulting vulner-
ability of beachfront structures be ascertained. When FEMA is provided with
accurate and reliable data concerning the beach and dune dimensions necessary
to prevent damages from at least a 100-year-level storm, risk assessment is much
more accurate, and construction standards and insurance premium rates can bet-
ter reflect the risks at a site. The calculated level of protection also provides a
target for nourishment dimensions, advanced-fill parameters, and poststorm re-
sponse needs. These considerations relate to projects other than USACE projects,
although USACE does not necessarily provide for 100-year protection. See Ap-
pendix H for USACE design procedures.
NFIP Planning Basis
The NFIP uses an event defined as the base flood (also referred to as a 100-
yearfloo~ as a specific benchmark for program administration. A base flood has
a 1 percent chance of being equaled or exceeded in a particular year (44 CFR 594.
Although a 100-year flood is a statistical rather than an exact description of a
particular storm, the base-flood concept is used for planning. Detailed studies are
conducted of coastal floodplains to identify base-flood elevations and to develop
Flood Insurance Rate Maps (FIRMs). These maps become the quantified bench-
marks for program planning and measuring response to NFIP policies and regu-
lations. The detailed studies result in identification and designation of coastal
high-hazard zones. They define different degrees of hazard in the 100-year coastal
floodplain.
For V zones (see Box 3-3), the NFIP is concerned with "the inland extent of
a 3-foot breaking wave, coincident with the location where the stillwater depth
during the 100-year flood decreases to less than 4 feet" (FEMA, 1986~. For A
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66
BEA CH NO URISHMENT AND PR O TECTI ON
zones, the stillwater-based flood elevation is the principal concern because the A-
zone portion of the 100-year floodplain is by definition not subject to high-
velocity wave action. A zones include contributions from waves less than 3 feet
high (FEMA, 1986~. The essential coastal hazard data used to identify zone
boundaries include:
.
100-year stillwater elevation for the base flood,
· topographic data, and
· land-cover area.
Additional data used to identify erosion and runup include:
· bathymetry,
· storm meteorology, and
· wave characteristics.
Also of interest are data on previous coastal flooding and historical erosion trends
associated with severe storms (FEMA, 1989~. The NFIP recognizes differences
in shore conditions on a regional basis. In determining coastal base-flood eleva-
tions, FEMA includes wave heights in some areas and wave runup in others. It is
appropriate in some cases to include both in the calculation of the base-flood
elevation.
Of particular concern with respect to shore protection is the current practice
of establishing risk zones in beach communities without high erosion hazard
provisions. This practice does not accurately portray the damage risk to buildings
because beach erosion can be episodic owing to meteorological cycles that may
produce several years of stability followed by several years of stormy conditions
that dramatically alter the beach geometry. Thus, the mapping could provide
estimates of risk that are either too large or too small. Remapping to update
FIRMs for coastal communities involves surveys of individual locations every 5
to 8 years. As a result, the period between the original photography for base maps
and the adoption of new maps may be so long that the new maps, when published,
inaccurately depict the physical condition of an eroding shore. In some cases, the
same topographic data may be used in several successive studies with no updat-
ing to reflect changes in the beach and dune geometry.
Program Management Issues
The National Research Council (NRC, 1990) previously reported that more
stringent criteria and management could be applied to improve NFIP effective-
ness in reducing erosion hazards. It recommended:
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THE FEDERAL ROLE IN BEACH NOURISHMENT
67
· measures to delineate better the areas in which the federal government
would offer flood insurance,
comprehensive state or local management programs guided by minimum
standards for all areas experiencing significant erosion,
· changes in flood insurance rates and availability to reflect erosion and
economic risks more accurately, and
· changes to make more viable the relocation or demolition of buildings
threatened with immediate collapse owing to erosion.
.
In contrast to calls for more stringent management of coastal floodplains to
reduce erosion and storm damage risk, other public and political calls have been
made to relax or eliminate regulatory and policy standards when storm hazards
have been reduced through beach nourishment. There have also been calls to
reduce other governmental restrictions or requirements based on erosion condi-
tions that have been mitigated. Florida, South Carolina' New Jersey, and Michi-
gan have adopted provisions to recognize beach nourishment in the calculation of
erosion rates and the establishment of baselines. For example, under the 1990
Beachfront Management Act of South Carolina, the erosion baseline is moved in
a seaward direction based on the nourishment design after 3 years of satisfactory
project performance. The design must meet comprehensive and prescriptive cri-
teria addressing postfill erosion rates, profile equilibration, minimum fill density
(115 m3/foot alongshore), minimum length (9 km), minimum design level (a
storm with a 10-year recurrence interval), and design life. Additional require-
ments include monitoring, maintenance, and funding commitments. Under the
Florida Beach and Shore Preservation Act of 1989 (Florida Statutes, Chapter
161:909-928), erosion rates are adjusted such that "no erosion shall be considered
to have occurred during that portion of the project life" for "Authorized Beach
Restoration Projects." These projects must meet similar design and maintenance
criteria (Florida DNR, 1989; South Carolina General Assembly, 1990; South
Carolina Coastal Council, 1991~.
Congress, in examining possible refinements to the NFIP, expressed concern
that credit was not given to the diminishment of coastal hazards and the reduction
or elimination of historic erosion trends as a result of beach nourishment pro-
grams. On September 23, 1994, President Clinton signed into law the Riegle
Community Development and Regulatory Improvement Act of 1994 (P.L. 103-
325), Title V of which includes NFIP reform provisions. In addition to previous
concerns with evaluating the effect of beach nourishment on mapped flood haz-
ards, FEMA is now responsible for administering mitigation assistance grants for
technically feasible and cost-effective mitigation plans that can include beach
nourishment activities. This legislation also requires FEMA to prepare a report to
Congress that assesses the full economic impact of mapping erosion hazard areas
under the NFIP.
There is a public perception issue as well. Flood insurance underwritten by
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68
BEACHNOURISHMENT AND PROTECTION
the federal government for buildings in beachfront areas is seen by some to be
subsidizing the development of barrier islands; beaches; and more particularly,
the investment properties of affluent individuals with shorefront homes. FEMA
(1994' reports that overall post-1985 buildings in V zones as a class are not
subsidized collected premiums have exceeded claims paid. Construction prior
to adoption of the FIRMs and of floodplain construction standards is subsidized
to some extent, as are structures that are exposed to the increasing coastal hazards
associated with continuing erosion and shoreline retreat. Whether development
on barrier islands and in close proximity to barrier beaches should be allowed
also is strongly debated.
Relating Beach Nourishment to the NFIP
The policy issues hinge on how well beach nourishment projects can provide
long-term protection by reducing or mitigating coastal hazards and whether this
protection is temporary or permanent. Once this protection is established, it is
possible to assess how these benefits can be reflected in the administration of
flood insurance. The options for addressing beach nourishment projects in the
NFIP range from no official recognition through intermediate measures (e.g.,
requiring nourishment projects as a precondition for issuance of insurance and
economic incentives to sustain and maintain projects' to ultimately reduce insur-
ance premiums and constructions standards. In the latter case, a related question
is whether any cost savings by reducing insurance premiums or constructions
standards should be applied to further hazard mitigation measures or whether the
savings should be passed directly to owners of protected properties for discretion-
ary use. The answer to this question is as much a political determination as it is a
managerial and technical one. The nature and uncertainty of coastal hazards and
the effectiveness and ability to sustain mitigation measures argue for a conserva-
tive insurance management approach.
THE U.S. GEOLOGICAL SURVEY
Since its creation in 1879, the USGS has been the nation's leading earth
science research organization. The USGS's basic authorization for surveys, in-
vestigations, and research is included in an act of March 3, 1879 (43 U.S.C. 315.
USGS scientists conduct both applied and fundamental studies as part of the
agency's mission to investigate, collect, analyze, monitor, and disseminate criti-
cal information about the nation's energy, mineral, water, and land resources.
With this knowledge, society can develop economically and environmentally
sound plans to manage the earth' s resources and address issues.
To address the need for fundamental geoscience information and improve
our scientific understanding of the earth and its processes, the USGS has initiated
the National Marine and Coastal Geology Program. The program includes a wide
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THE FEDERAL ROLE IN BEACH NOURISHMENT
71
by a governmental agency. Fees based on the assessed value of the resource may
be negotiated, except that no fee may be assessed in the case of the federal
government.
Any federal agency that proposes to use OCS sand must enter into a memo-
randum of agreement with the Secretary of the Interior detailing the potential use
of the resource prior to that use. The cognizant congressional committees also are
notified.
The sand and gravel found in OCS waters are also used by the construction
industry, and the OCSLA requires that they be treated as other minerals that
might be mined on the OCS: the MMS is responsible for activities associated
with leasing, exploration, development, production, and royalty management.
The leases are granted on the basis of competitive bidding. The MMS is
also responsible for preparing documents for the National Environmental Protec-
tion Act process to ensure that no environmental degradation is caused by OCS
. .
mlnlng.
With increasing demand for suitable sand and diminishing nearshore re-
sources, the MMS is working cooperatively with 10 Atlantic and Gulf coast states
on projects to identify and assess OCS sand resources for coastal restoration and
shore protection needs (see, for example, Conkwright and Cast, 1994~.
An MMS study of particular interest to the beach nourishment topic is "Wave
Climate Modeling and Evaluation Relative to Sand Mining on Ship Shoal, Off-
shore Louisiana." This study, awarded in July 1994, is using numerical modeling
to examine the current and wave fields around Ship Shoal, an offshore geological
feature located in the central Gulf of Mexico, adjacent to Louisiana barrier is-
lands. Ship Shoal is being considered as a source of clean quartz sand for beach
replenishment along the rapidly deteriorating Isles Dernieres. The model will be
used to help predict the resultant effects on the wave and current field in this area,
using scenarios involving various degrees and quantities of sand removal from
the shoal. Specifically, the study involves (1) numerical modeling of wave
energy transformation and decay across the inner shelf encompassing Ship Shoal
and the nearshore adjacent Isles Dernieres, (2) development of a nearshore sedi-
ment transport model along the Isles Dernieres, and (3) quantification of changes
in (1) and (2) due to removal of various sediment quantities based on likely
scenarios of sand removed.
EROSION HAZARD REDUCTION PROGRAMS
OF FEDERAL AGENCIES
Previous sections described the approaches that the USACE, NOAA, and
FEMA use to protect shores, reduce coastal hazards, and manage erosion. It is
challenging to identify a consistent holistic federal approach to shore protection.
There are opportunities for federal agencies to coordinate more closely to de-
velop a position that better complements the objectives of each other. An exami
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72
BEACHNOURISHMENT AND PROTECTION
nation of the ways in which nourishment can help achieve the management goals
of each agency follows.
Technical Premises for Protecting Natural Beaches
Beach management and regulatory programs administered by NOAA,
FEMA, and most state agencies are based on the premise that beaches are sub-
jected to long-term erosion and communities are becoming progressively more
vulnerable to storm damage. The distance between beachfront buildings and the
water is an essential factor in protection. There are two reference lines on a
developed beach: the shoreline and the line of construction. The dune, when
present, and dry beach must fit between them. Cross-shore dimensions of a natu-
ral beach are a function of wave energy and sediment supply. When the sediment
supply seaward of the line of construction is diminished, the shoreline moves
toward the line of construction. The first beach feature to disappear is the berm,
followed by the dune, whose location on the beach depends on an adequately
wide berm to dissipate wave energy. The berm, or active, unvegetated portion of
the dry beach, is the direct product of waves and currents. The berm may retreat
to the toe of the dune during a storm. If the dune is unable to migrate because
construction is located close behind, the dune becomes narrower until it eventu-
ally disappears. The buildings that may once have been safely located landward
of the primary dune become located in the dune zone as the dune migrates in a
landward direction. Ultimately, the buildings may be effectively seaward of the
dunes and vulnerable to direct attack by storm waves. In the long term, however,
the beach features do not disappear but are translated landward.
Construction setback lines, erosion rate based or otherwise, have been estab-
lished in some states in an effort to reduce damage in areas subjected to shoreline
retreat. Destruction of dunes and conversion of beaches for development elimi-
nate or reduce the natural storm and erosion protective benefits that an entire
coastal community relies on during periods of high tides, storm surges (on the
Atlantic and Gulf coasts), waves, and currents. Construction landward of a pri-
mary dune and naturally wide berm remains relatively safe from the impacts of
coastal storms if those beach units are of a dimension that would naturally be
present at that particular shorefront location. However, in erosion-prone areas,
buildings built landward of the natural dune 10 to 20 years ago often occupy
middune or back berm locations today, as long-term erosion continues the shore-
line regression. This continuing landward migration of the beach and the result-
ing diminishment of the berm and dune width increase the risk of storm damage
to waterfront buildings. Thus, construction standards for zones in which a struc-
ture was originally built may become insufficient at that same location as the risk
of damage increases over time due to beach erosion seaward of the building.
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THE FEDERAL ROLE IN BEACH NOURISHMENT
73
Program Planning
FEMA and USACE programs to reduce damages differ because they have
different missions, and different planning criteria apply. Successful beach nour-
ishment projects provide area-wide direct physical protection to shores. The level
of protection in the design process varies among projects based on analyses of
costs and benefits. The NFIP provides financial protection for construction in
hazard zones and attempts to mitigate the expected risks to individual buildings.
That program is primarily concerned with the base-flood elevation and the asso-
ciated effects of wave runup and wave height in the coastal hazard zone insofar as
these forces threaten individual buildings. The differences between the two pro-
grams need to be understood in order to relate the performance of beach nourish-
ment projects to FEMA's objectives for mitigation of coastal hazards.
Correlating Beach Nourishment Project Performance with Coastal
Floodplain Hazard Mitigation
FEMA is reluctant to assign hazard reduction benefits to a temporary form of
hazard reduction. This reluctance has been reinforced by the continuing contro-
versy over technical issues, the physical performance of beach nourishment
projects, and the economic benefits derived. As a result, determining the appro-
priate relationship between beach nourishment and flood insurance is neither
simple nor straightforward. The differences in planning concepts used by the
USACE and FEMA in the administration of their programs provide no direct
correlation between the protective benefits of beach nourishment projects and the
hazard mitigation aspects of the NFIP. The capability of beach nourishment
projects to reduce hazards to meet NFIP objectives varies significantly among
projects. Therefore, the contribution of a beach nourishment project to the miti-
gation of NFIP coastal hazards must be determined on a project-by-project basis.
ACCREDITING BEACH NOURISHMENT PROJECTS TO QUALIFY
FOR FLOOD INSURANCE BENEFITS
Accreditation is an acknowledgment by a certifying entity, such as FEMA or
a state coastal regulatory agency (NOAA-approved), that a project is capable of
performing to design specifications and has therefore effectively reduced an ex-
isting hazard. Certain minimum criteria may be required in order to qualify for
accreditation of certain programs. Accreditation of hazard protection projects to
qualify for NFIP benefits is not a new concept. For example, dikes and levees on
interior river systems that have met construction, maintenance, and level-of-
protection criteria acceptable to FEMA have resulted in reduced flood hazard
determinations for buildings constructed on the floodplain (44 CFR 65.10~. These
types of projects differ significantly from beach nourishment projects in that they
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74
BEACHNOURISHMENT AND PROTECTION
are designed to provide protection from a 100-year flood with no physical degra-
dation or reduction in the level of protection; a beach nourishment project is
designed to be sacrificial. Nevertheless, the accreditation program used by FEMA
and associated reductions in hazard determinations have set a precedent for con-
sidering a similar NFIP response for shore protection by beach nourishment
projects under which the project would receive favorable actuarial treatment or
other relief from requirements that govern coverage under the NFIP. The accredi-
tation concept, as currently applied in the NFIP, does not address the larger issue
of whether flood insurance should be made available or be continued in areas
where residential or commercial structures are physically located on a beach
rather than behind a dune line. Under these conditions, the risk may be too high
from an actuarial perspective to justify flood insurance, regardless of construc-
tion standards. Requiring a beach nourishment project as a precondition for the
issuance of insurance may be a reasonable option; however, existing statutes
require that the NFIP provide insurance regardless of the actuarial risk. Recent
congressional debate on insurance availability for beachfront property indicates
that risk in these areas is acceptable for now but deserves further study.
Level of Protection
The NFIP requires a rational basis for determining construction standards
and premium rates. Establishing a level of protection for a coastal floodplain
subject to wave attack, or overwash as a result of storm surges, is difficult. As
discussed previously, the NFIP 100-year base-flood elevation is often not the
same design storm benchmark used for USACE beach nourishment projects.
Further, beach nourishment projects are often designed to have less protection
than a 100-year storm. Nevertheless, the presence of an effectively designed and
maintained beach nourishment project for such a storm can increase the level of
protection within the coastal hazard zones mapped by FEMA in one or more of
the following ways:
· by preventing waves or wave runup from reaching the V zone,
· by reducing wave runup in the V zone,
· by reducing the height of waves that reach into V zones as a result of
episodic erosion or because of high flood elevations, and
· by providing a buffer between the open ocean and the V zone on existing
maps.
The actual reduction of risk provided by the beach fill varies considerably
over the life of the nourishment project as the advanced-fill dimensions are
reduced through erosion. Long-term protection depends on program performance
and the commitment to maintain the project through renourishment. Standards or
criteria used for accreditation must consider minimum protective berm dimen
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THE FEDERAL ROLE IN BEACH NOURISHMENT
75
signs and advanced-fill requirements in terms of berm width and height seaward
of the line of construction in order to maintain the level of protection that lies
landward of the advanced-fill section. Thus, maintenance of the advanced fill in
accordance with the program's planned renourishment cycle (and on an excep-
tional basis as needed) would be a fundamental consideration for accreditation of
a project for flood insurance purposes. Because V zones generally extend beyond
project boundaries, it is also appropriate to consider hazard mitigation benefits
that may accrue to shorefronts downdrift of project boundaries. Another impor-
tant consideration is that shorefront property remains exposed to the potential for
flooding regardless of the presence of a beach nourishment project. This situation
results from the potential for flooding caused by an anomalously large storm or
an underestimation of the base flood, either of which could result in a breach in
protective dunes or other shorefront protective structures, storm tidal surges in
back bay areas, or a combination of both. As a result, beach nourishment projects
can mitigate but do not eliminate either the coastal flooding hazard or the poten-
tial for damage from waves, depending on the severity and character of the
storms. This fact merits attention when considering setback requirements and
construction standards.
ADDRESSING BEACH NOURISHMENT IN THE NFIP
Specific alternatives that could be considered in the management of accred-
ited beach nourishment sites within the NFIP include:
.
.
.
.
basing construction standards, premium rates, or both on the risk reduc-
tion potential of the program at the expected least-protective dimensions
of the fill (in effect, relocating the hazard potential zones owing to the
relief provided by the fill);
basing construction standards? premium rates, or both on the determined
median fill dimension that would provide a median risk reduction poten-
tial over the project life;
establishing the alternatives of an option for a beach nourishment pro-
gram as a precondition for the issuance or continuation of flood insurance
or the setting of higher insurance rates;
maintaining construction standards and premium rates at levels appropri-
ate to base-flood elevations determined prior to beach nourishment;
· evaluating protective benefits of beach nourishment programs, maintain-
ing rates, and allocating any savings to funding at the local, regional, or
national levels for coastal hazard mitigation projects;
· providing grants or funding to design nourishment projects, conduct site-
specific erosion analyses, or monitor project performance;
· establishing a federal entity to provide technical assistance to states or
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76
BEACH NOURISHMENT AND PROTECTION
communities in carrying out technical work when the USACE is not
involved in the project; and
contributing supplemental funding to existing beach nourishment projects
to increase the level of protection or life span of the fill.
Understanding the differences between a federal and a commercial insurance
program is essential to beach restoration decision making. Unlike commercial
insurance, the federal government relies on premiums to fund the basic flood
insurance program rather than on earnings from invested premiums. When own-
ers' contributions to flood insurance are reduced, the reduction could be consid-
ered a subsidy because there are few economic incentives for owners to invest
construction cost or insurance premium savings in further coastal hazard mitiga
tion measures.
Although nourishment may be an effective tool at some locations for com-
bating beach loss for a reasonable period, economic conditions may change over
time so as to undermine continuing financial support for project maintenance.
Abandonment of a nourishment program could result in progressively increasing
exposure to erosion hazards for new and old construction alike and the ability of
NFIP funds to pay claims for coastal flood damages.
FIRMs are created to reflect the flood hazards that exist. At issue is whether
the maps should be revised to reflect mitigation of flood hazards provided by
beach nourishment projects. FIRMs delineate the flood risks for a given area in
order to provide construction standards appropriate to the risk at that site. Consid-
eration of lower construction standards at a site that has been protected by nour-
ishment must include potential project performance over time. The physical life
expectancy of new construction in a beach area may well be 100 or more years,
whereas the life expectancy of a beach fill project without renourishment may be
less than 10 years. The design life of beach nourishment programs today is on the
order of 50 years, and in many cases the financial and sand resources needed to
sustain projects are based on expectations that the resources will be available,
rather than on the allocation of mineral resources or financial arrangements to
ensure that funds are generated and held in reserve for the planned renourish-
ments. Should any of these needs not be met, a building constructed today land-
ward of the nourished beach may well become exposed to prenourishment condi-
tions at some point during its useable life (Davison et al., 1992,19931.
Construction Standards
Prior to the NFIP, some dwellings in the coastal floodplains were constructed
so as to reduce flood or wave impacts. Most buildings adjacent to the beaches and
many buildings landward of them were below 100-year base-flood elevations.
Examples of construction that mitigated coastal hazards include some two-story
homes on New Jersey's barrier islands dating from the 1920s and 1930s. The
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THE FEDERAL ROLE IN BEACH NOURISHMENT
77
principal living areas were on the second rather than the ground floors. Construc-
tion that mitigated wave impact damage included the placement of buildings on
pilings at elevations above anticipated storm surges and associated waves. Dur-
ing the Ash Wednesday storm of 1962 that ravaged the Atlantic coast, such
residences on pilings that were of sufficient dimensions and were driven to ad-
equate depths survived the event. At the same time, virtually all other shorefront
buildings that were below the flood elevation on some barrier islands, including
many behind seawalls, were destroyed, along with their protective seawalls
(Podufaly, 19621. This experience provides the basis for the construction stan-
dards required by the NFIP and by some state and local regulations or ordinances
regarding new construction or substantial reconstruction in zones or locations
deemed vulnerable to flood or wave impacts.
Required construction standards usually include pile specifications, eleva-
tion requirements, and attachment specifications. Adherence to these standards
results in hazard reduction to the property to which they are applied as well as to
surrounding properties. Secondary damage may result if one building fails and
the debris impacts adjacent buildings during a storm that includes high storm
surges. Vulnerability to these impacts decreases when beaches have been wid-
ened, but, as noted earlier, the time duration of a single nourishment project may
well be less than the physical life of the structure.
There are pressures for relaxation of construction standards in response to
hazard mitigation benefits provided by a beach nourishment project. The appro-
priateness of construction standards needs to be considered in the full context of
coastal floodplain hazards, including uncertainties associated with coastal storms,
beach nourishment project performance, time scales, and economic effects. The
principal economic leverage available to ensure sound construction is the avail-
ability of affordable flood insurance and federal disaster assistance. Relaxation of
construction standards in response to hazard mitigation benefits of uncertain
duration could potentially undermine the NFIP's leverage to hold communities
accountable for sound floodplain management practices and property owners
accountable for construction that reduces risk.
With respect to the argument that reducing construction standards could
serve as an incentive for maintenance of a beach nourishment project, the fact
that beach nourishment projects and flood insurance serve different objectives
must be considered. There is no guarantee that a local community will meet its
obligations to maintain a beach nourishment program. If the NFIP were to accept
lower construction standards, it would thus become hostage to the uncertainties
of local sponsor support without the means to force retrofits of buildings to meet
more stringent standards. Even if retrofitting were politically feasible, it might
not be practical or even possible for some buildings. Faced with such a situation,
the only choices open for the NFIP would be to accept the greater liability or to
cancel flood insurance for the affected area. Thus, any short-term savings to
property owners achieved through relaxation of construction standards need to be
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78
BEACHNOURISHMENT AND PROTECTION
balanced against the long-term implications of increased exposure of buildings to
severe episodic storms and increased liability for risk that would be incurred by
the NFIP.
Setback requirements are usually established at the state or local level to
separate land areas that are appropriate for construction from the dune and beach
zones. These requirements serve to preserve the protective and recreational
values of the dune and beach. Setback lines are usually established as fixed-
reference features such as the landward toe of the primary dune or as a line a
certain distance from a reference location (e.g., the mean high-tide line or the +3-
m contour line). In recent years there has been a trend toward using the average
annual erosion rate as a multiplier for moving the setback line landward in an
effort to preserve the cross-shore geometry over time. Stabilization or prograda-
tion of the shoreline through nourishment of the beach could potentially move the
setback line or the reference feature farther seaward following nourishment un-
less their locations were fixed at the prenourishment project locations.
Premium Rate Adjustments
An alternative to lowering construction or zoning standards is a reduction in
flood insurance premium rates. This concept is used by FEMA in its relatively
new Community Rating System program. The program was developed to provide
. ~ . ,~ . . . .
an Incentive for communities to conduct a variety of activities or institute built ,
ing practices that help reduce flood hazards. Credit is given in the form of pre-
mium reductions throughout the entire community when these endeavors are
carried out. However, details of implementation of long-term project viability
remain to be developed. Acceptable criteria through accurate monitoring of
project performance will relate to the reduction of risk that is directly attributable
to a project.
Annual premium rates are established relative to the risk of damage that is
determined for a particular property. The risk level is associated with the hazard
zone and the base-flood elevation at the site when the building was initially
constructed or when the community began participating in the NFIP. Recent
NFIP reform provisions call for FEMA to prepare a report to Congress that
assesses the full economic impacts of mapping erosion hazard zones (E zones). If
the mapping of E zones is eventually mandated by Congress to designate beach
areas with a determined average annual erosion rate, a subheading, Em, could be
included to designate erosion that has been mitigated, at least temporarily, through
beach nourishment. Considering the fact that beach nourishment can reduce dam-
age potential, reflection of this benefit in the annual premium rate merits consid
erat~on.
An alternative to rate reductions in which savings accrue directly to property
owners (and are effectively lost to the NFIP) would be funding technical assis-
tance to communities in support of floodplain management activities or of en
OCR for page 79
THE FEDERAL ROLE IN BEACH NOURISHMENT
79
trancing the performance of beach nourishment projects, sponsoring local beach
nourishment projects to reduce the NFIP's risk in hazard-prone coastal areas, and
funding emergency fills to restore a project's shore protection benefits after a
severe storm. This approach would enhance NFIP objectives for predisaster haz-
ard mitigation and FEMA's postdisaster restoration of community services and
damaged buildings while returning the benefit to NFIP participants on a program-
matic rather than individual basis.
A STRATEGY FOR REDUCING COASTAL HAZARDS
Federal shore protection programs undertaken by the USACE, the FEMA-
administered NFIP, and the NOAA-administered CZMA are based on different
agency missions. These programs also use different planning factors to mitigate
the effects of erosion and reduce coastal hazard potential. Understanding the
differences in missions and in the manner in which protection benefits are deter-
mined is necessary to establish whether and to what degree the buffer provided by
the beach nourishment project mitigates the hazards as defined by these agencies.
The actual level of protection provided by a beach nourishment program
changes during the renourishment cycle and during storms. It is difficult to quan-
tify the actual level of protection that is provided and to relate it to flood insur-
ance program concepts and coastal hazards management plans for uses in esti-
mating how much of the individual program objective has been realized.
However, the design section of the fill plan is the minimum section for which the
USACE calculates the benefits to be derived from the fill (see Figure 4-6~. At any
instant of time, the actual section is somewhere between the design section and
the advanced-fill section.
The USACE, FEMA, and NOAA could work more closely in developing a
comprehensive federal approach to mitigating coastal hazards and determining
the role of beach nourishment at any given site. Given the uniqueness of each
beach community, the answer may lie in the development of comprehensive
beach erosion and hazard mitigation management plans for discrete reaches of
the shoreline. A comprehensive plan for a beach town or a region encompassing
a geomorphic or littoral compartment could include improved construction stan-
dards, removal of some or all dwellings from particularly hazardous locations,
and the use of beach nourishment to reduce the hazard potential. Federal involve-
ment in placing material on the beach through the USACE could be predicated on
an assessment that considers a cost-effective, long-range management plan for
the proposed nourishment area. Inclusion in the plan of the full range of manage-
ment options and goals that the USACE, FEMA, and NOAA are attempting to
accomplish is appropriate.
Criteria could be established for accrediting beach nourishment programs by
FEMA that would either allow for development within certain limits or would
disallow accreditation for situations that increased exposure or risk in the coastal
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80
BEACH NOURISHMENT AND PROTECTION
floodplain. NFIP responses that could limit exposure and risk to the insurer in-
clude:
· an approved beach nourishment program that includes a frontal dune
(where appropriated with restrictions that preclude further development of
.
high-erosion-risk zones;
no remapping of hazard areas;
· no reduction in construction standards as they pertain to shore protection;
· a dedicated funding commitment for the life of the program for all planned
and emergency renourishments;
a requirement that sand sources be available and dedicated (including
sand rights) to the program for initial placement, all planned renour~sh-
ment, and a reasonable number of contingency replenishments;
a requirement for alternate or secondary sources of sand should physical
conditions reduce sand from sources that are dedicated to the program;
· a requirement for a contingency plan that would restore an adequate de-
sign level of protection for the subaerial beach following storm losses;
· a requirement for a program to perform as designed within some accept-
able level of uncertainty; and
· a requirement for long-term monitoring with dedicated funding covering
the full program.
.
REFERENCES
Conkwright, R. D., and R. A. Cast. 1994. Potential Offshore Sand Resources in Northern Maryland
Shoal Waters. Maryland Geological Survey, Coastal and Estuarine Geology File Report 94-8.
Unpublished.
Culliton, T. J., M. A. Warren, T. R. Goodspeed, D. G. Remer, C. M. Blackwell, and J. J. McConough
III. 1990. 50 Years of Population Change Along the National's Coasts, 1960-2010. Rockville,
Md.: National Oceanic and Atmospheric Administration.
Davison, A. T., R. J. Nicholls, and S. P. Leatherman. 1992. Beach nourishment as a coastal manage-
ment tool: an annotated bibliography on developments associated with the artificial nourish-
ment of beaches. Journal of Coastal Research 8(4):984-1022.
Davison, A. T., C. P. Ulrich, and R. J. Nicholls. 1993. Accreditation of beach nourishment projects:
an issues discussion. Shore and Beach 61(4):9-15.
Department of Commerce. 1994. 1992-1993 Biennial Report to Congress on the Administration of
the Coastal Zone Management Act, Volume II. Washington, D.C.: U.S. Department of Com-
merce.
FEMA. 1986. Coastal Construction Manual, FEMA-55. Washington, D.C.: Federal Insurance Ad-
ministration, Federal Emergency Management Agency.
FEMA. 1989. Guidelines and Specifications for Wave Elevation Determination and V Zone Map-
ping. Third draft report. Washington, D.C.: Federal Insurance Administration, Federal Emer-
gency Management Agency.
FEMA. 1994. National Flood Insurance Program: Flood Insurance Rate Review. Washington, D.C.:
Federal Insurance Administration, Federal Emergency Management Agency.
Florida DNR. 1989. Rules and Procedures for Coastal Construction and Excavation. Pp. 909-928,
Chapter 16B-33. Tallahassee: Florida Department of Natural Resources.
OCR for page 81
THE FEDERAL ROLE IN BEACH NOURISHMENT
81
Holmes, C. M. 1993. Introduction of Coastal Data Collection Theme. Paper presented at the 58th
Meeting of the Coastal Engineering Research Board, June 1993, Atlantic City, N.J.
NOAA. 1994. 1994 Biennial Report to Congress on the Administration of the Coastal Zone Manage-
ment Act. Washington, D.C.: National Oceanic and Atmospheric Administration.
NRC. 1990. Managing Coastal Erosion. Water Science and Technology Board and Marine Board,
Commission on Engineering and Technical Systems. Washington, D.C.: National Academy
Press.
O'Brien, M. P. 1985. Beach stabilization by sand replenishment. Shore and Beach 53(1):15.
Podufaly, E. T. 1962. Operation five-high. Shore and Beach 30(2):9-17.
South Carolina Coastal Council. 1991. Regulations for Permitting in Critical Areas of the State's
Coastal Zone. Charleston: South Carolina Coastal Council.
South Carolina General Assembly. 1990. South Carolina Beach Front Management Act. Columbia:
South Carolina General Assembly.
USACE. 1991. History of the Coastal Engineering Research Center, 1963-1983. Vol. I, WES Library
History Series. Vicksburg, Miss.: Coastal Engineering Research Center, U.S. Army Engineer
Waterways Experiment Station, U.S. Army Corps of Engineers.
USACE. 1994. Shoreline Protection and Beach Nourishment Projects of the U.S. Army Corps of
Engineers. IWR Report 94-PS-1. Fort Belvoir, Va.: Institute of Water Resources, Water Re-
sources Support Center, U.S. Army Corps of Engineers.
Williams, S.J., S. Penland, and A.H. Sallenger Jr., (eds.). 1992. Louisiana barrier island erosion
study. Atlas of Shoreline Changes in Louisiana from 1853 to 1989. USGS Misc. Inv. Series.
No. I-2150-A. 107 pp.
Representative terms from entire chapter:
flood insurance
