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7
Conclusions and Recommendations
GENERAL FINDINGS
Beach nourishment projects can be used effectively to provide a broader
beach, which affords protection from storm and flooding damage within human
time scales (decades, not centuries) when:
stood,
· projects are carried out on sites at which the erosion processes are under
· uncertainties in design and prediction are accounted for realistically, and
· state-of-the-art engineering standards of planning and design are used.
Well-designed, -constructed, and -maintained projects provide the storm damage
reduction and erosion protection for which they are intended. Beach nourishment
may not be technically or economically justified for some sites, particularly those
with high rates of natural erosion.
RECOMMENDATION: Federal, state, and local authorities with
responsibility for coastal protection should view beach nourishment
as a viable alternative for providing shore protection and for restor-
ing lost recreational beach assets.
The planning and execution of successful beach nourishment projects can
best be accomplished through a broadly based coalition of disciplines and inter-
ests that brings together all the scientific, engineering, economic, and governance
knowledge and experience available. Narrowly developed projects have resulted
140
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CONCLUSIONS AND RECOMMENDATIONS
141
in technical, environmental, or economic deficiencies. All project planning should
recognize the need for maintenance.
RECOMMENDATION: Federal, state, and local agencies in-
volved with beach nourishment projects should require multidisci-
plinary project planning, design, monitoring, and evaluation. The
methodology employed should:
.
establish the goals and expectations of the project and its con-
tinuation as a long-term program;
establish clear and quantifiable measures of success;
establish and maintain an effective monitoring program that
supports the management, design, and execution of subsequent
nourishment cycles;
develop and maintain a public awareness program; and
account for the uncertainties implicit in shore protection mea-
sures through the implementation of contingency planning and
the identification of future sources of both renourishment
material and project funding.
SPECIFIC FINDINGS
Design
The design of a successful beach nourishment project depends on an under-
standing of the underlying causes of erosion at the site and a capacity to model or
evaluate quantitatively the coastal processes, such as wave climate variations and
the cross-shore and alongshore transport rates of sediments. Deficiencies exist in
our understanding of many of these processes and adversely affect our ability to
predict the evolution and fate of nourishment fill; even when the basic processes
are understood, large uncertainties can remain in numerical evaluations. Further,
there are significant differences among coasts' geological settings, geomorpholo-
gies, sand sources and sinks, sediment characteristics, and physical forces, such
as waves, tides, currents, and winds. The great diversity of conditions and the mix
of coastal processes result in major regional differences that make it neither
practicable nor desirable to establish a national standard design for beach nour-
ishment projects. Each must be designed to satisfy the conditions at its location.
Nourished beaches usually experience significant spatial alongshore varia-
tions that range from high rates of erosion to accretion. When locations erode
faster than anticipated (erosional hot spots), reserve protection capacity may be
lost and the design compromised along a portion of the beach. The reflourished
beach will require more sand than the net background erosion from the project
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142
BEACH NOURISHMENT AND PROTECTION
because erosional hot spots require overfill. In addition, accretional areas store
advanced fill, and the accretion should not be deducted from the estimated ero-
sion. Designers underestimate renourishment needs when they base their esti-
mates solely on net erosion projections. A potential savings can be realized when
the initial renourishment interval is shortened and less advanced fill is placed in
the first renourishment in order that fine tuning of the project to address erosional
hot spots can be implemented at an early stage.
RECOMMENDATION: The design methodology for beach nour-
ishment projects should include the following:
· design profiles based on natural profiles at the site suitably
adjusted for nourishment grain size rather than straight line
segments or other unrealistic approximations;
spreading losses owing to the nourishment project accounted
for explicitly in the design;
volumes adjusted to account for rock outcrops and seawalls in
order to provide sufficient volume to nourish the entire profile
from the berm or dune to the seaward limit of the active pro-
file and avoid underestimating fill requirements;
sediment performance characteristics included in the analysis
of sediment considered for use as beach nourishment material,
with specific attention to the equilibrium shape of the profile,
the transportability of the sediment alongshore, and the erod-
ibility of the material during a storm; these factors used at
first in conjunction with overfill and renourishment factors
and later as a substitute for these factors as more experience is
gained;
the possibility of erosional hot spots recognized in the design;
analytical and numerical models used to estimate end losses
that will be caused by spreading of the fill material to adjacent
.
beaches;
the Blrst renourishment time interval shortened to allow for
uncertainties in alongshore erosion rates, thus enabling cor-
rection of erosional hot spots before the design is compro-
mised and avoiding overbuilding of accretional areas; and
safety factors developed to account for variability and uncer-
tainty and applied appropriately to both design volumes and
advanced-fill volumes.
Although technologically outdated, the Shore Protection Manual published
by the U.S. Army Corps of Engineers (USAGE) in 1984 is the de facto standard
for coastal engineering throughout most of the world. Strong legal constraints
and liability considerations reinforce its continued use in the United States by
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CONCLUSIONS AND RECOMMENDATIONS
engineers in private practice, even though it
by the USACE.
143
is no longer the design standard used
RECOMMENDATION: The U.S. Army Corps of Engineers
should publish detailed and comprehensive state-of-the-art engi-
neering guidance on the design of beach nourishment projects, ei-
ther as part of the planned Coastal Engineering Manual or in a
separate document.
Differences exist in the planning and design methodologies used by the
USACE field offices. Some of these differences relate to regional differences in
the beaches that have been designed (South Atlantic barrier islands versus West
coast bluff-backed beaches). Design approaches must therefore vary to account
for regional differences. However, other differences in designs are a result of the
methodologies selected, some of which do not employ state-of-the-art practices
realistically. This situation results in uneven effectiveness in project design and
contributes to less than optimum solutions.
RECOMMENDATION: The U.S. Army Corps of Engineers
should develop and implement a consistent methodology for beach
nourishment design while retaining sufficient flexibility to accom-
modate regional variations in physical conditions.
Structural Alternatives
Fixed Structures
Fixed (hardj structures, when appropriately designed and placed at suitable
locations, can improve the performance of some beach nourishment projects.
These structures may be perpendicular to the shore, to reduce end losses (e.g.,
jetties and groins); offshore and shore parallel, to reduce local wave intensity
(e.g., detached breakwaters); and onshore and shore parallel (e.g., seawalls), to
provide a reserve capability to prevent flooding and wave attack where dunes
cannot or do not exist, especially in areas like the Pacific coast, where storm
surges are small and to reduce wind-blown losses to the land. Broad prohibitions
on the use of fixed structures in conjunction with beach nourishment projects can
contribute to suboptimal project performance where fixed structures can provide
secondary storm damage reduction or are needed to anchor the ends of projects.
RECOMMENDATION: Agencies should modify their prescrip-
tive laws, regulations, and management plans for the coast to allow
the use of fixed structures in conjunction with beach nourishment
projects where project performance can be significantly improved,
out-of-project negative effects are acceptably small or are mitigated
as necessary, and beach access or use is not impaired. The costs of
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44
BEACHNOURISHMENT AND PROTECTION
the structures should not exceed the savings achieved by increasing
the level of protection or the times between successive renourish-
ments. Environmental impacts should also be considered.
Structures do not increase the volume of sand in the littoral system; they
simply rearrange and control the movement of the sand that is placed or is already
there. Failure to provide fill along with the structures often results in erosion of
the beach system at another location. Even when a groin field is filled to its
holding capacity, localized erosion effects may nevertheless occur. These effects
need to be addressed more effectively and accommodated in project design and
construction.
RECOMMENDATION: Each fixed structure that is used in con-
junction with a beach nourishment project should be filled to the
upper limit of its holding capacity if it would otherwise accumulate
sand. Where uncertainties exist, fill should exceed the calculated
upper limit of the holding capacity of the structure. If a beach nour-
ishment project is not maintained, adverse effects of any structure
should be mitigated or the structure should be removed.
Nontraditional Shore Protection Devices
The techniques used in conventional shore protection have had the benefit of
decades of field performance and the development of demonstrated design mod-
els to predict that performance. This experience has clearly shown that there are
no cheap and easy solutions to the difficult and expensive process of protecting
the shore while maintaining its environmental assets. The use of nontraditional
shore protection devices needs to be approached carefully because of uncertain-
ties about their performance and beneficial value relative to traditional technol-
ogy, for which performance capabilities are established.
The Committee on Beach Nourishment and Protection is concerned that
some nontraditional devices that involve large structures placed near the shore
may cause unfavorable conditions that will be difficult and expensive to correct.
At the same time, the committee believes that technical innovation should be
encouraged and that entrepreneurs should have access to the marketplace in this
field. Evaluation of any beach protection system is expensive because of the size
of any meaningful experiment and is time consuming because of concerns for
testing under a full set of climate conditions. It is prudent to consider as experi-
mental new approaches that purport to be low-cost solutions until their perfor-
mance has been adequately demonstrated. Further, unconventional approaches
that do not involve addition of sand to the littoral system from outside sources
and that involve the trapping or rearrangement of sand must be recognized as
providing local improvement only at the expense of neighboring areas that lose
this material. A uniform and effective methodology consisting of a performance
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CONCLUSIONS AND RECOMMENDATIONS
145
based specification is needed for evaluating the effectiveness of nontraditional
shore protection and beach stabilization and restoration devices so that any inter-
ested agency or private buyer can be more fully informed before committing to
their use.
RECOMMENDATION: The performance of nontraditional shore
protection and beach stabilization and restoration devices should be
successfully demonstrated under a performance-based specification
before these devices are used in lieu of conventional shore protec-
tion and beach stabilization and restoration alternatives, including
beach nourishment. A performance-based specification should be
developed by the U.S. Army Corps of Engineers for nontraditional
devices to guide their application in projects in which there is fed-
eral involvement. This specification or a similar procedure devel-
oped objectively by qualified coastal engineers acting in a third-
party role should be used to guide the application of nontraditional
devices in nonfederal projects.
Adequate studies and engineering analyses of borrow sites are critical to the
success of a nourishment effort. In particular, the impacts of creating a local
depression in the sea bottom on offshore sand movement from the nourished
beach need to be assessed in order to determine the effects on the littoral system
and any mitigation measures that need to be implemented. It is necessary to avoid
dredging within the depth of active sediment transport and minimize wave modi-
fications that would adversely affect the nourishment project.
RECOMMENDATION: Sponsors of beach nourishment projects
should use a methodology for selecting borrow sites that assesses:
· the required quality and quantity of sand,
· the effect of borrow sites on adjacent beaches when these sites
are located within the closure depth of the beach profile or are
part of a shoal that normally feeds the downdrift beach, and
· the need for, and negative and positive effects of, bypassing
sand.
If sand must be taken from borrow sites located within closure
depths, it should be done as a planned sand bypass operation that is
designed specifically to mitigate the effects of a feature or structure
that interrupts the littoral movement of sand.
Relevance of Sea-Level Rise
Relative sea-level changes are occurring along most U.S. coasts. The effects
of sea-level rise are particularly important along the Atlantic and Gulf coasts with
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46
BEACHNOURISHMENT AND PROTECTION
low-lying topography. Erosion or beach recession, which is the result of current
relative sea-level rise, is incorporated into the background erosion rate. The
overall effect of a gradual relative sea-level rise at the present rate will not be
detectable in the rate of beach loss. If the relative sea-level rise accelerates, the
beach loss also will accelerate. Because beach nourishment programs consist of a
series of projects, and because reevaluation of erosion rates is included in the
design of projects, no additional considerations are necessary to account for
erosion that is induced by relative sea-level rise.
Sea-level change, however, is just one of many factors impacting beach
behavior. Its magnitude and relative importance are difficult to ascertain because
changes are masked by more dramatic near-term fluctuations caused by other
physical forces. Relative sea-level rise will probably remain a minor factor af-
fecting replenished beach durability during the next several decades.
Major Management Issues
Public Involvement
Before a beach nourishment project begins, there is a compelling need to
inform the public about:
· the anticipated time frame of the program (e.g., a 20-, 30-, or 50-year
program);
the nourishment intervals and especially the beach state or condition (e.g.,
width of dry beach) that will trigger renourishment;
the timing and extent of the expected profile adjustment and its impact on
.
beach widths;
the possible impacts of major storms on beach character and on projected
costs, sand volumes, and the timing between renourishment projects;
the potential occurrence of erosional hot spots and the requirements for
corrective action; and
the adjustment from the temporarily wider and steeper construction pro
file to the expected equilibrium profile.
Inadequacies in public involvement and information programs have exacer-
bated public controversy over beach nourishment. Measures to inform the inter-
ested and affected publics about beach nourishment projects have been inad-
equate with respect to design expectations for beach behavior and costs,
uncertainties in the design process, prediction of project performance, future
environmental conditions, and replenishment cycles. The promulgation of infor-
mation essential to public support of programs described in technical and design
manuals is not an effective substitute for well-designed and -executed public
involvement and information programs.
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CONCLUSIONS AND RECOMMENDATIONS
147
After a beach fill has been completed, there is a continuing need to regularly
update the public on its progress, including reports on the sand volumes and
beach widths remaining, the nature and extent of erosional hot spots, the condi-
tion of the storm berm, and the implications of this information.
RECOMMENDATION: Sponsors of beach nourishment pro-
grams should establish public information and involvement pro-
grams as an integral component of each beach nourishment project,
beginning with the design phase and continuing through the mainte-
nance stage.
Commitments for Long-Term Project Maintenance
The long-term financial commitment required to maintain a beach replenish-
ment program effectively is generally recognized by communities involved in
these projects but is not always incorporated into the planning process. The 50-
year life cycle for a typical USACE beach nourishment program is rarely, if ever,
paralleled by similar long-term planning by the public and local project sponsors.
In particular, an existing beach nourishment program may not be backed by
dedicated sand resources for the projected life of the program or for supplemental
renourishments that may be necessitated by severe storms or other factors. It is
inaccurate to characterize planned beach nourishments as a bona fide program
unless long-term planning and commitments to maintain a program are in place.
RECOMMENDATION: Given the long-term sand commitments
necessary to ensure sufficient sand for the planned life cycle of a
nourishment program, federal and state agencies should investigate
mechanisms that would help sponsors identify and, where feasible,
contract for or secure mineral rights to sources for long-term sand
commitments. These mechanisms may include the use of unconven-
tional sources for later cycles of nourishment so long as the pro-
jected costs are reflected in the cost-benefit analyses.
Sand deposits that are located in state waters and that are free to publicly
funded within-state beach nourishment projects are often not sufficient in quality
or quantity to sustain beach nourishment over a program's life. Sand sources
under federal jurisdiction on the continental shelf and administered by the Miner-
als Management Service of the U.S. Department of the Interior will become
increasingly important for the continued maintenance of some beach nourish-
ment programs. Existing mechanisms for allocating these mineral resources
through competitive bidding, and by negotiated agreement between the USACE
and the Minerals Management Service for projects involving federal cost sharing,
do not incorporate provisions for contracting forward for sand resources. Proce-
dures for allocating sand resources to accommodate long-term needs merit fur-
ther investigation.
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BEACH NOURISHMENT AND PROTECTION
RECOMMENDATION: When future renourishment sand
sources cannot be identified with certainty, each construction
project should independently meet the tests for economical viability.
Emergency Maintenance and Contingency Plans
The need for rapid emergency restoration of a beach or dune system can be
created by severe storms that exceed design criteria. When emergency restoration
is warranted, procedural delays caused by locating appropriate sources, obtaining
permits, and contracting for construction can further jeopardize endangered build-
ings and infrastructure. Contingency plans and arrangements are needed to facili-
tate the timely implementation of emergency restorations.
RECOMMENDATION: Program sponsors should develop con-
tingency plans for emergency repair of beach and dune systems
necessitated by severe storm damage as part of the beach nourish-
ment program at each site. Emergency-use borrow sites should be
identified as a minimum and the necessary permits obtained and
held in reserve when possible. Sponsors should investigate the feasi-
bility of and plan appropriately for expedited procurement proce-
dures to identify and secure dredging services from U.S. contrac
tors.
Project Scope
Beach nourishment programs are often undertaken without due consider-
ation for their relationship to and impact on other portions of the littoral cell that
often cross political boundaries. Most programs encompass only a portion of an
area that can be considered a littoral geographic region or littoral cell. However,
actions in one area of a littoral cell have generally affected other areas in the cell
and, in some cases, areas in adjacent littoral cells. The length of a project has
typically been prescribed as the minimum design needed to protect an arbitrarily
specified shoreline sector without regard for uncertainties. The program scope
has not been adequately recognized by policies governing USACE beach nour-
ishment project planning, design, and approval. It is recognized that tough, less-
than-ideal choices must be made during the evolution of a project because of
jurisdictional, budgetary, and time constraints.
RECOMMENDATION: Beach nourishment programs should be
planned as part of an overall regional beach management plan. All
involved participants should take action to ensure that the process
used for planning, design, and approval of beach nourishment pro-
grams achieves this objective.
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CONCLUSIONS AND RECOMMENDATIONS
149
It is common for economic analyses to show that a broad range of potential
projects produces positive and comparable cost-benefit ratios, but the single
project beach width that provides maximum net benefits is selected as the federal
National Economic Development (NED) plan. Because of uncertainties in both
the design and the physical processes, selection of a plan larger than the NED
plan would provide a safety margin against uncertainty and variability. In many
cases, the larger project selection would not significantly change the cost-benefit
ratio but would significantly increase the margin of safety for reducing storm
damage.
RECOMMENDATION: The federal government should modify
its policies to allow for the selection of a project larger than the
National Economic Development plan as long as it provides a posi-
tive cost-benefit ratio and is within the financial capability of the
local sponsor. A sensitivity analysis should be performed for each
prospective and existing program for which one has not been done
in order to identify the scope of a more inclusive program that
would reduce the risks of excessive damage. The sensitivity analysis
should be applied to both the advanced-fill and design beach com-
ponents.
Measures of Success
There is no single measure of success for beach nourishment programs be-
cause programs usually serve a variety of objectives. Therefore, various mea-
sures of success need to be defined for beach nourishment programs. A program
may or may not be successful in meeting all objectives underlying its establish-
ment. Some of the performance measures may occur in the near term, such as a
program's response to physical forces. Other objectives may occur over a much
longer term for example, the realization of related shore community economic
development goals and reduction of shoreline retreat. Effective program perfor-
mance from an engineering perspective may or may not change the economic
conditions that motivated local support for a beach nourishment program because
socioeconomic conditions can change over the life of a program.
The fundamental measure of success is the life span of the beach fill and how
nearly actual performance conforms to predicted performance.
Success in enhancing recreation can be related to the width of the dry beach,
whereas success in shore protection is better evaluated in terms of the total sand
volume (subaerial and subaqueous) remaining in the program area and the protec-
tion it provides during storms. Two simple measures of a successful beach nour-
ishment program are the dry beach width and the volume per unit length of
shoreline remaining in the program area during its design life. Two more com
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150
BEACH NOURISHMENT AND PROTECTION
plex measures are the assessment of property damage avoided and the remaining
level of protection.
RECOMMENDATION: Sponsors of beach nourishment pro-
grams should quantify and report on four measures of performance
of beach nourishment projects. The measures are:
· dry beach width,
· total sand volume remaining,
poststorm damage assessments, and
residual protection capability.
The federal process for renourishing a beach from the reconnaissance study
through the first nourishment typically takes 10 to 15 years. On authorized
projects that require only preconstruction engineering, design, and real estate (or
right-of-way) acquisition, the process takes 5 to 6 years. These long planning
times burden the local sponsor with years of uncertainty about storm damage.
Some of the delays are caused by the rigid and sequential federal process, which
includes detailed agency reviews and waiting times for next-phase funding. Other
delays are caused by slippage in USACE planning schedules. To speed the plan-
ning process, the federal approval process can be streamlined and delays mini-
mized through contracting technical services. The Water Resources Develop-
ment Act of 1992 enabled local governments to undertake the planning process
for authorized projects to reduce schedule slippage. That authority has not been
exercised because local governments are required to finance the federal share of
project costs until after project construction and acceptance by the USACE.
RECOMMENDATION: The federal government should reduce
the time now needed to process a beach nourishment project. The
following steps should be taken:
revise the federal approval process to streamline approvals
and funding time frames,
increase the level of contracting for technical services by con-
sultants to the USACE, and
· modify the laws and regulations to make federal funding for
locally constructed federal projects available upon approval
of preconstruction engineering and design by the Assistant
Secretary of the Army for Civil Works.
Environmental and Monitoring Issues
Most beach nourishment programs are inadequately monitored following
construction. Monitoring of the physical environment and the performance of the
fill material is often too limited in scope and duration to quantify project perfor-
mance adequately. Comprehensive assessments of the effects on biological re
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CONCLUSIONS AND RECOMMENDATIONS
151
sources have been limited, especially at sand borrow sites. Resources associated
with beach habitats are affected both positively and negatively, with negative
effects generally of short duration relative to the expected renourishment interval.
Alterations to biological resources in the sand borrow areas are generally of
longer duration, and the consequences of those changes have not been well de-
fined.
RECOMMENDATION: Sponsors of all beach nourishment
projects and programs should establish adequate monitoring pro-
grams to evaluate changes in the physical and environmental condi-
tions. The scope of the monitoring program should be appropriate
to the scale of the nourishment program, and the monitoring design
should recognize how the data will be used to make project-related
decisions. Monitoring data should be analyzed in a timely manner
and used to make management and operational decisions regarding
continuation of the beach nourishment project or program.
RECOMMENDATION: Project sponsors should plan beach res-
toration programs so as to avoid significant long-term degradation
of the biological resources that are affected, either directly or indi-
rectly by construction activities. Emphasis should be on monitoring
resources and habitats of greatest concern, including the borrow
areas. The appropriateness of the dredging equipment to be used
and the manner in which dredged materials will be discharged
should also be considered. Where feasible, construction projects
should incorporate design features that would enhance biological
resources of concern.
Costs and Benefits
Assessing and Allocating Costs and Benefits
Beach nourishment programs result in economic benefits in a variety of
forms and to a variety of recipients. Cost-share ratios arbitrarily mandated by
Congress do not necessarily reflect the actual distribution of benefits; nor do
these ratios take into account the impact of navigation projects on nearby and
downdrift shores.
RECOMMENDATION: The full range of benefits that accrue
from a beach nourishment program should be assessed and quanti-
fied. Cost sharing should more accurately reflect the spread of ben-
efits that stem from a project.
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BEACH NOURISHMENT AND PROTECTION
RECOMMENDATION: The federal government should bear an
appropriate share of beach nourishment project costs when it can
be clearly established that federal navigation projects have exacer-
bated the erosion problems on adjacent or downdrift shores, even
when these projects were not the only or even the primary cause.
Cost-benefit Analysis
Although the theory and methodology for conceptualizing and measuring
costs and benefits are well developed, the valuation of beach nourishment pro-
grams does not take full advantage of these capabilities. As a result, social costs
and benefits are not always fully represented in the analysis used to determine
whether a program should be undertaken or in the choice among alternative
project designs and implementation strategies.
The procedures for calculating costs and benefits are overly restrictive, al-
lowing only storm damage reduction and limited recreational benefits. There is a
wide range of potential costs and benefits that are not currently counted, such as
the full complement of recreation benefits and the beneficial effects to adjacent
beaches outside a project's domain.
RECOMMENDATION: The U.S. Army Corps of Engineers
should modify the rules governing both its cost-benefit analysis and
its choices among alternative project design and implementation
strategies so that the true social costs and benefits provided to the
entire coastal region are captured. In particular, the policy should
recognize the storm damage reduction and recreational values to
the total area affected and account for the benefits of sand transport
to adjacent areas.
Because only limited postconstruction assessment of beach nourishment pro-
grams has taken place, there is little information about the types of costs and
benefits (beyond storm damage reduction and recreation) that might accrue from
these projects and might be sufficiently significant to warrant measurement.
RECOMMENDATION: The U.S. Army Corps of Engineers
should conduct postconstruction economic evaluations to identify
and measure the wide range of costs and benefits that actually result
from beach nourishment programs. A particular focus of this effort
should be reassessment of the categories of costs and benefits that
should be included in future cost-benefit analysis procedures.
The procedures used for calculating the benefits that are allowed under cur-
rent cost-benefit guidelines do not uniformly reflect state-of-the-art methodol-
ogy. This point applies to assessing recreational benefits and may apply to other
areas as well.
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CONCLUSIONS AND RECOMMENDATIONS
RECOMMENDATION: To improve the basis for policy analysis
and decision making, the U.S. Army Corps of Engineers should
become aware of and employ the methodological progress that has
been made in economic valuation, especially in measuring
nonmarket benefits such as recreation. The guidelines for measur-
ing benefits should be updated and applied consistently throughout
all U.S. Army Corps of Engineers divisions and districts.
RECOMMENDATION: The U.S. Army Corps of Engineers
should improve the basis for economic valuation of beach nourish-
ment projects by:
· reassessing the categories of costs and benefits included in
evaluating a project,
· incorporating uncertainties in assessing uncertain costs and
benefits both with and without the project,
· investigating behavioral responses stimulated by beach nour-
ishment projects; and their policy ramifications, and
· coupling projects with local growth and land-use plans to in-
crease the net benefits of projects and designing financing
schemes that provide efficient incentives.
Coordination of Navigation and Shore Protection Projects
153
The USACE constructs and maintains both navigation and beach nourish-
ment projects. The implementation of one type of project can have significant
impacts on the other; yet the costs and benefits of the two types of activities have
not been considered jointly insofar as the committee can determine.
Construction and maintenance of navigation projects that result in the trap-
ping of sand from adjacent beaches often cause erosion of those beaches. A1-
though the USACE has authority to address cause and effect on specific projects,
current practice does not encourage coordination and correlation of the effects of
navigation projects with the erosion mitigation and nourishment needs of nearby
beaches. The occasional placement of beach-quality sand obtained from naviga-
tion projects on eroding beaches is more a matter of economic convenience as a
least-cost disposal option rather than a planned action to minimize disruption of
the littoral system. The many instances in which dredged beach-quality sand has
been disposed of offshore rather than on adjacent beaches does not recognize the
economic value of the sand. The cost of offshore disposal is greater than esti-
mated in the past when only the direct cost of offshore disposal was considered.
RECOMMENDATION: Beach-quality sand dredged from federal
navigation projects should be used for beach nourishment projects
where the benefits to the latter exceed the extra direct costs to the
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154
Role of Beach Nourishment
BEACHNOURISH1tIENT AND PROTECTION
navigation projects Implementing such an approach requires that a
navigation project be "charged" the cost of any sand budget deficit
that it might impose on the adjacent shoreline.
RECOMMENDATION: The U.S. Army Corps of Engineers
should modify its policies to require both consideration of the eco-
nomic value of the sand and the placement of beach-quality sand
dredged from federal navigation projects in the littoral system from
which it was removed. The U.S. Army Corps of Engineers should
coordinate and correlate the construction and maintenance of
coastal navigation projects with erosion mitigation along adjacent
beaches.
RECOMMENDATION: The U.S. Army Corps of Engineers
should revise its procedures for cost-benefit analysis of navigation
and beach nourishment projects in which there is federal involve-
ment to require calculation of both the benefits provided and the
costs that one type of project imposes on another.
Flood Protection
A beach nourishment program located seaward of upland buildings or infra-
structure provides storm damage reduction relative to the level of protection that
would exist if there were no program. Adequate methods exist for approximating
the damage reduction owing to a beach nourishment program; however, there is
significant uncertainty about the frequency of storm conditions that could com-
promise project performance. Nevertheless, the increase in the level of protection
provided by beach nourishment projects and programs supports a finding of
reduction in flooding risk, which would merit a reduction in insurance premiums.
RECOMMENDATION: The Federal Emergency Management
Agency should weigh the effect of an adequately designed, con-
structed, and maintained beach nourishment program on flooding
risk and hence on flood insurance premiums.
Qualification of Engineered Beaches for Disaster Assistance
Under the disaster assistance program administered by the Federal Emer-
gency Management Agency, the definition of an engineered beach that is used to
qualify for payment of sand losses from a beach nourishment program does not
provide sufficient specific criteria to define the engineering adequacy of pro-
posed programs.
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CONCLUSIONS AND RECOMMENDATIONS
RECOMMENDATION: The Federal Emergency Management
Agency should revise its definition of and requirements for an engi-
neered beach to consist of technical criteria, monitoring require-
ments, and measures to promote accountability for program perfor-
mance.
· The technical basis for certification should be the establish-
ment of a design level of storm and flood protection, including
the level of protection provided by the design beach and the
advanced-fill section seaward of the design portion. The Fed-
eral Emergency Management Agency should establish a stan-
dard risk factor and then contract for engineering studies to
establish return periods or other appropriate design standards
that will result in the establishment of standard risk for each
of the major coastal regions. Designs for beaches intended to
qualify for engineered beach status should meet the joint storm
and flood levels appropriate to these return periods or design
standards.
An assessment of the capacity of a beach to protect against
storms should be updated through periodic surveys conducted
at least annually to document the evolution of the beach and to
determine any change in storm and flood damage reduction
potential.
Identification of sources of emergency nourishment material
should be made well before the need arises.
155
There are two mechanisms for the Federal Emergency Management Agency
to participate in emergency actions following a severe storm. If there is a disaster
declaration by the President, public assistance funds may be used to support the
costs of replacing sand lost to an engineered beach. Second, mitigation funds may
be used to restore beach and dune dimensions as soon as possible to protect
against subsequent storm damage. At present, these are the only standing emer-
gency assistance programs available at the federal level for shore protection and
are relied on by coastal communities following damaging storms.
RECOMMENDATION: Beach and dune dimensions lost as the
result of a severe storm should be restored as quickly as possible to
protect against subsequent storm damage. The Federal Emergency
Management Agency should continue to provide support for these
essential activities.
Shore Construction Standards
Although nourishment offers effective reduction of storm damages to on-
shore construction, the level of protection afforded by the fill is subject to rapid
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156
BEACH NOURISHMENT AND PROTECTION
reduction during a major storm and will diminish through time if the beach is not
maintained by subsequent renourishment. It is not advisable to reduce or elimi-
nate construction or location standards based on prefill hazard assessments or
dune protection setback requirements because of (1) uncertainties about continu-
ing financial means and political will to maintain a beach nourishment program
in the absence of a requirement to do so and (2) uncertainties about sediment
availability in the absence of dedicated sediment resources.
RECOMMENDATION:
In recognition of uncertainties in the pre-
diction of coastal processes, cognizant government authorities
should establish and maintain construction and location require-
ments to set construction back from the storm hazard regardless of
whether a beach nourishment project is in place.
RECOMMENDATION: In recognition of uncertainties in the pre-
diction of coastal processes, the Federal Emergency Management
Agency should establish and maintain construction standards for
buildings or lots within the benefit area of a beach nourishment
program and should prepare Flood Insurance Rate maps as if a
beach nourishment project were not in place.
.
Research Needs to Support Design and Prediction Capabilities
There is a need for research to better understand the physical, economic, and
biological processes associated with beach nourishment programs and to mini-
mize uncertainties. Research is needed on a regional basis to accommodate re-
gional differences in these processes. In particular, a more complete understand-
ing is needed in the following areas to improve the design of beach nourishment
programs:
.
the natural variability of beach profiles and how they respond to changing
wave and current conditions and sediment textures;
the significance of profile closure depths beyond which the profiles ap-
pear to show minimal responses to changing wave conditions, particularly
the degree to which sediment exchange occurs between the beach and
offshore out to these closure depths and how these depths can be pre-
dicted as a function of sediment and wave conditions;
· the choice of grain size and other characteristics of the nourishment mate-
rial for best retention on the beach and how that choice affects the dynam-
ics of the beach profiles and alongshore spreading of the nourishment
sediment;
· the further development of cross-shore sediment transport models related
to profile changes; and
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CONCLUSIONS AND RECOMMENDATIONS
157
· the causes of erosional hot spots occurring on natural beaches and within
beach nourishment programs.
RECOMMENDATION: An intensive study for a few large-scale
beach nourishment programs should be undertaken by a third-party
group of investigators under federal sponsorship. The objective of
the study should be to test the validity of current predictive methods
and design assumptions and improve prediction and design meth-
odologies further. The study should include postconstruction assess-
ment of the costs and economic benefits of the programs and the
overall effects on economic development.
Directional Wave Data
On a major project, especially at a site with complex bathymetry, directional
wave data are essential to verify the design methodology and to improve perfor-
~nance in future beach nourishment. These data are needed to establish the coastal
wave climate for the program. Collateral uses of the data should be considered
when justifying the cost of measuring waves.
RECOMMENDATION: The U.S. Army Corps of Engineers
should require the collection, analysis, and dissemination of direc-
tional wave data as part of major beach nourishment programs in
which there is a federal cost share.
Erosion Data
There is a need for a uniform, national, reliable data base on historical
erosion rates. Erosion rate data based on historical charts collected by the Na-
tional Oceanic and Atmospheric Administration and profile data collected by the
USACE and some local agencies are uneven and of varying usefulness.
RECOMMENDATION: The U.S. Army Corps of Engineers, the
National Oceanic and Atmospheric Administration, and the U.S.
Geological Survey should undertake a cooperative program to es-
tablish standardized decadal rates of erosion or accretion for all
U.S. shorelines subject to significant change over this time scale.
The detailed data base used in these assessments should be readily
available to coastal engineers and scientists.
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Representative terms from entire chapter:
nourishment projects
