realism in response to shoreline erosion problems

Proceedings.05 the International meeting (Nantes, hrance, 17-20 October, 1991)
Special issue
Coastal protection, International experiences and prospects
REALISM IN RESPONSE TO SHORELINE EROSION
PROBLEMS:
A CALL FOR A NEW WORLD ORDER
Onin H. PILKEY
Dept. of Geology. Ffogram for the study of developed sh&es.
27706 USA
and
~ u k University,
e
Durham. North Carolina,
William J. NEAL
Dept. of Geology, Grand Valley State University, Allendale, Michigan 49401 USA
R6sumC :Partant du simpIe constat d'un recui sensible de la ligne de rivage de part et d'autre de l'atlantique
nord @ourse limiter Bcette aire gbgraphique), I'auteur passe en revue les diverses solutions qui s'offrcnt P qui
veut y faire face. Bien que et c'est dans l'ordre des doses ces solutions fassent I'objet d'une prisentation
dCtaill6e. d'autres possibilit& qui relevent d'ailleurs de I'amknagement global des littoraux sont Cgalement
p&ent&s (definition demnes inconstructiblesdu fait de la menace B terme...). Au plan de l'ing6ni6rie &ti&re.
chacune dcs techniques employ& est discut& : avantages et inconviaients du systkme sont ainsi prbentb.
L'opinion de I'auteur est que, finalement, il n'existe pas plus de "remhde-miracle" que de mCthode
intrinsQuement perverse : tout est 2 la fois affaire de situation gbgraphique et de choix pditique P ckhelle
pertinente. Pour autant, la trop grande assurance de certains, I'arrogance de corps pourrait-on dire. doit &re
critiqubet I'autewappellescientifiques et inghieurs l'imovation pourque 1'Cventail des solutions soit a la
fois le plus large et le plus 6 b l e .
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Mots-clis :Etats-Unis, ingni6rie &&re. ambgement du littoral, gestion du littoral. tanage, temp6tes.
INTRODUCTION
The gun emplacementsthat faced seaward, waiting for the enemy, are now falling into
the sea; lost to the unanticipated force of shoreline retreat. North Carolina's civil-war Fort
Fisher, Portugal's 19th century Forte Novo, and hundreds of W W I1 bunkers on both sides of
the Atlanticare victims of the sea-level rise and coastal erosion. The sea is not selective, and
post-WW I1 coastal development of houses, businesses, roads, and utility services are lost or
threatened daily. Society now.chooses to arm the. shore against nature; to stabilize the position
of the shoreline. Too often this decision to stabilize is like an out-dated Maginot Line, exacting
a severeprice economicallyand environmentally,while not providing a long-term solution.
The problem of stabilization is not only a problem of what is engineeringly feasible
versus what is environmentally sound, but one of whether to protect private property or public
beaches, and who should pay for the type of protection chosen, and for how long. Coming up
with reasonable responses to shoreline retreat is all the more difficult because solutions usually
are sought in a crisis atmosphere, when the beach is under the doorstep, or the cliff edge at the
foundation. Short-term solutionsare devised for long-term problems. The long-term nature of
the shoreline erosion crisis is accentuated by the global sea-level rise. Western society's
socioeconomicconcepts of property rights and the attitude of being able to useltreat private
property without regard to adjacent property or public domain does not bend to the natural
dynamics of the shore, or eommon sense.
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WHAT ARE THE OPTIONS?
Traditionally, hard stabilization is the solution of choice. The mighty seawalls of the
Romans set a trend to out-engineer nature. The late 20th century has seen movement toward
soft stabilization; an attempt to engineer by imitating nature. The realization that society may
have to bend with natural dynamics is leading more and more in the direction of relocation of
shorefront development as the most viable long-term solution; already encouraged by and
framed in some legal codes. The long term reasoning is (Kaufman a &., 1985) that we can
strategically retreat now or we can retreat in tactical disarray in the future.
What are the advantages/disadvunt4gec of each option ?
The following is a view engendered by experience on the U.S. East and Gulf Coast
banier island systems. These generalizations probably apply in most areas of the world.
I.
Hard Stabilization
A. Wave Blocking Devices (the seawall family)
1. Advantages
Seawalls are the best choice society's only goal is to protect property.
2. Disadvantages
Seawalls resylt in beach degradation (narrowing to complete loss), as
well as loss of recreational value (e.g., debris on beach, danger to swimmers or other beach
users, access loss, and general loss of esthetics). Construction and maintenance are costly.
B. Sand Trapping Devices (groins; breakwaters)
1. Advantages
These structures build up thelocal beach, thereby improving beach
quality and storm protection. Recreational value may be improved.
2. Disadvantages
Trapped sand is robbed from the littoral drift causing shoreline erosion
in the downdrift direction. At the same time, the structures block lateral beach access for
recreation, may pose a danger to swimmers, often contribute debris to the beach, and are
unsightly. Historically, such structures lead to more stabilization. Construction and
maintenance are costly.
IL
Soft Stabilization
A. Beach Replenishment
I. Advantages
This option is best if society wishes to maintain a beach, and protect
property developments that people are unwilling to move. The quality of
an eroding beach is maintained, or improved, and its role of storm
protector preserved. When sand is eroded, it may benefit downdrift
shorelines. Recreational and esthetic qualities are maintained or improved.
2. Disadvantages
Beach nourishment must be viewed as temporary; very costly to install
and maintain. Usually the impact on the native marine biota is negative.
Suitable replenishmentlnourishrnentsand may not always be available.
B. Bulldozing
1. Advantages
This very short-term, crisis response may give a very short-term
sediment gain, and contribute to beach maintenance for short-term protection. Short-term costs
may be lower than other options, but this is false long-term economy.
2. Disadvantages
Bulldozing provides extremely temporary nourishment to the upper beach,
and actually may erode the lower beach, resulting in beach narrowing. No new sand is added
to the littoral system, so the process must be repeated after each storm. The process disturbs
the beach biota.
III. Relocation (Move or Demolish Development)
A. Advantages
Relocation is the best solution if a community's only priority is to save beaches.
This long-term solution is a policy of noninrerference with the migrating beach.
Beach quality and storm protection, esthetics, recreational value, and biota are
conserved.
B. Disadvantages
This approach is politically the most difficult, as well as costly, although no
more so than other options for the long term. Demolition may be required, or a
move away from the shorefront, losing recreational access. Land loss will
occur.
The implementation of the relocation option, and avoiding creating new problem areas
through shoreline development requires legislative regulation, economic incentives and
disincentives, indlor cost sharing. These legal solutions can be at the federal, state, or local
government level and include coastal zone management or planning, zoning, construction
setback requirements, "rolling" setbacks where the regulated zone migrates with the shoreline
(e.g., buildings must be moved as they come into the erosion zone, or buildings
destroyedfdamaged by shoreline erosion can not be reconstructed/repaired), or prohibitions
against certain types of structures (e.g., no high-rise buildings). Economic disincentives
include higher premiums to insure structures in the erosional zone, o r passive disincentives
such as the prohibition of loansfgrants to construcrlreplace roads and services in a coastal
erosion zone. Incentives include such programs as allowance to use insurance monies to move
a threatened structure, or low-interest loans for the same purpose.
All of the stabilization options and approaches must be viewed as a long-term
commitment. Unfortunately, the "crisis atmosphere" negates long-term planning. The public
generally is not fully informed of the long-term implications of all of these approaches. For
example, beach replenishment should never be viewed as a short-term solution. Likewise,
long-term commitment is different than long-term feasibility. Will the federal, state, or local
government be able to continue to pay for beach nourishment in 30 years, 50 years, and so on?
Will a quality sand supply remain available? Maintenance also must be part of the long-term
plan and its feasibility. Chicago is a mega-example of the potential problem. The city's
Micial-fdl coast is protected by miles of seawalls, revetments, and groins. Maintenance of
this complex of shore hardening structures was neglected for decades, until a
stodflood/erosion crisis in 1987. The esthetic and economic value of the shorefront was
greatly reduced and the city now faces massive repair and replacement at a very high cost
(Chrzastowski, 1991).
ANSWERS TO CRITICAL QUESTIONS
Ideally, decisions to attempt new shoreline stabilization or maintain existing
stabilization should be guided by a balanced set of objectives (e.g., is the community priority to
protect property, preserve mxeational beaches, or both?). Communities need to ask the right
questions, even more so in shoreline-erosion crisis situations. The following responses to
such stabiliition and structural solution questions are those that we believe coastal engineers
and geologists should be giving.
Predicting sand behavior
Can We Predict the Behavior of Beach Sand?
No. All coastal engineering practices and all shoreline response alternatives require
knowledge of sand movement for their successful implementation. Thus predicting the
behavior of beach sand, whether it involves life span of a replenished beach or the downdrift
impact of a groin, is of critical importance. But we cannot predict the behavior of sand in a time
Erame of use to mankind. There are a number of reasons for this:
1. The basic assumptions that underlie most engineering equations for sand transport
are highly questionable. Such assumptions usually include (a) all sand transport is by wave
orbital/seafloor interactions, (b) stonn driven currents do not carry sand offshore, and (c) there
is a seaward depth of closure beyond which sand is not transported offshore. Frequently the
models assume that a storm will not occur.
2. Coastal processes must be chaotic, but they are not treated as systems in chaos.
Sediment movement is in chaos because storms which dominate coastal processes are
controlled by the atmosphere which is a system in chaos. One cannot predict the frequency,
magnitude, direction, duration, and fetch of the next storm, large or small. Sediment
movement is also controlled by wave motion and local currents which obey non-linear fluid
dynamic equations. Nonlineat~systemshave non-periodical solutions.
SeawaIls
Do seawalk cause erosion?
Yes. If you measure erosion by change in volume of the subearial beach. Often it is
argued that the wall was put .in because of erosion (as measured by shoreline retreat) and
therefore the wall didn't cause the erosion. True enough! Since the real societal question is
whether or not the wall damaged the beach, it is best to use the term de~radationrather than
dc$$
interactions
Do seawalls degrade beaches?
Yes.
How do seawalls degrade beaches? (Pilkey & Wright, 1988; Tait & Griggs, 1991)
1. Placement degradation - some walls are placed seaward of the high-tide line.
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2. Passive degradation Shoreline retreat continues after the wall is emplaced thus
mimwing the beach. Any wall built at the back of an eroding beach (and most are) will result
in eventual beach loss.
3. Active degradation - The wall actively causes erosion by wave reflection, etc. The
effectiveness of active beach degradation is controversial however (Kraus 1988). Most
-men?
as to whether walls degrade beaches or not are arguments as to whether active
epradat~onoccurs. These arguments over a mechanism should not be confused with the
generic question; do seawalls degrade beaches?.
Are rhere exceptions?
Of course, but these are few in number. Most claims of exceptions are based on short
term observations. A common example is a wall built immediately after a storm where the
beach widens, at first, due to storm recovery.
How long does it takefir a seawall to degrade beaches?
Perhaps anywhere from 2 to 60 years. Two to three decades is a common time spanfor
degradation on U.S. East Coast beaches. For this reason, short term declarations that a seawall
has caused no problems are meaningless. The fact that seawalls may take a long time to cause
serious damage requires politicians to take a very long view on the subject, a most difficult
thing in most political systems.
What is the very long term impact of seawalk?
Narrowed beaches, higher wave energy leading to bigger and better seawalls (Hall and
Pilkey 1991).
Do seawalk protect buildings?
Yes.
Do seawalls protect bluffs?
.
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To the extent that bluff retreat is due to subaerial processes (running water erosion,
chemical weathering, frost wedging, etc.) walls don't protect bluffs (Noms, 1990). Much
depends on the height and composition of the bluff.
Why do seawallsfail?
Inadequate engineering.
Groins
Do groins cause erosion?
Yes.
Are groins effective in general?
A subjective answer is that the net impact of groins and groin fields, worldwide, has
been negative. That is, more is lost in terms of shorelie damage than has been saved in terms
of shoreline buildup. This situation varies widely, of course.
Where can groins be used without causing damage?
At the extreme end of a sand transport system, such as at the tip of a cuspate foreland is
one such location. Secondly, groins can, on long stabilized shorelines, provide the only
beaches for a community. This is the situation in Mommouth Beach and Seabright, New
Jersey where, without groins, there would be no beaches.
Can groins increase the durability of replenished beaches?
Yes, providing there is a significant longshore component of sand movement from the
replenished beach. Once the replenished beach retreats landward of the tip of the groin
however, reduction in sand supply of downdrift beaches will commence. Offshore breakwaters
How do breakwaters diferfrrn groins?
Groins and breakwaters both trap sand and build out beaches. They also both cause
sand deficits in the downdrift direction. The major difference between groins and offshore
breakwaters is that the latter will cause storm waves to break offshore ' a d will thereby afford
an additional measure of protection for beach front buildings.
One device solutions
In the U.S. and especially on the Great Lakes, there are dozens of companies selling
single shoreline stabilization devices that are alleged to work anywhere, anytime to protect
buildings or build up beaches. These structures are generally given catchy names, such as sand
grabbex, wave buster, surge breaker, sea scape and sta-beach (no suggestion is made as to
whether these particular devices or approaches do or don't work). The one-device companies
often support their device using a wide variety of claims some of which follow:
1. Jt worked in Florida. Usually the place where it allegedly worked is at least SO0
miles away.
2. Professor "Jones" of State University tested and evaluated the structure. Sometimes
Professor Jones's tests are inconclusive. Most often such tests are made under very restricted
conditions.
3. This device will work on anv kind of shoreline. This is never the case. Each
shoreline situation quires a different approach.
4. Thousands of Cubic meters of sand pays bv here and our device will onlv ~ r a ba
small fraction of i~
-cially
5. This device will not impact on downdrift beaches Anything that holds sand
in one place will impact on neighboring beaches.
6. This device bri'n~sin sand. not nonnallv in the littoral svstem. Nonsense.
7. Here is a photo show in^ the success of our structure. Such photos must be
~xaminedclosely. Some before and after photos used by salesmen are very misleading.
Common tactics are comparing high and low tide and high and low lake level scenes or before
and after storm recovery photos.
. . 8. J'hD
~tin correctlv. This, or some variety of this, is a common explanation for failure of a device
to work as advertised. But a company that puts in a device knowing it's not put in comectly is
at fault, not local officials.
9. This device has been ~ublishedin the engineering literature. Scientists and engineers
know that publication in the technical literature guaranteesnothing about quality. In addition,
much of the coastal engineering literature is not refereed.
10. This is low cost shore ~rotection. There is no low cost, long term shoreline
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protection on ocean shorelines.
Beach replenishment
Can we predict rhe lifespan of arti)Wal beaches?
No. On the U.S. East Coast predictions have been dismal and are almost always over
optimistic (Pilkey and Clayton 1987). This means that costs have also been underestimated.
Storms are primarily responsible for loss of artificial beaches and we will not be able to predict
beach durabiity until we can predict storm frequency and intensity.
Is beach &sign and prediction of lifspcu~shopeless?
No. The Gold Coast, Australia experience (Smith, 1990) shows that a local statistical
model based on long term observations is useful in predicting replenished beach durability
(withe m r bars). Using current engineering models to design beaches has frequently failed.
Do replenished beachesprovide effective storm proteaion?
Yes,if large enough volumes of sand are involved. Often, however, a replenished
beach is good for only one significant storm.
Do replenished beaches erode faster than natural beaches?
In general, yes.
Do replenished beaches substantially recoverfrom s t o m ?
No, in general this does not happen on U.S. East Coast banier islands. Smith (1990)
reports a well documented 80% recovery 'of a storm-lost beach on the Gold Coast
Why is there so much &agreement over the rates of loss of replenished beaches?
Replenished beaches disappear at dramatically different rates along their length. Thus it
is often a judgement call concerning beach lifespan. Often art5cial beaches disappear most
quickly along reaches which were the most critically eroding to begin with.
Does replenishment sand moved ofshore countfor anything?
No, especially not as far as the beachfront community is concerned. The assertion that
the sand will permanently reside offshore and help buffer storm waves is probably not hue. To
begin with, the sand does not permanently reside offshore and also such offshore
replenishment sand has little impact on storm wave dampening because the storm surge
effectively negates its role.
Does beach replenishment impact significantly on the biota?
Yes,especially in hard ground and reef areas. However, the requisite systematic and
long tenn studies of Mlenishment biota impacts have never been made on any coast.
Relocation
Is the relocation alternative a permanent solution?
No. How "permanent" depends on how far back buildings are moved and what is the
potential rate of shoreline retreat?
Why move back when we could replenish or arnwr?
Seawalls destroy beaches and replenishment is very costly.
Is the relocation option costly?
It depends. The U.S. Federal Flood Insurance Program intends to encourage relocation
via insurance premiums.
Is h e relocation option costly compared to replenishment or annoring?
It depends on the situation. Moving Miami Beach and Atlantic City, New Jersey back
from the retreating shoreline is much more costly than moving back communities of single
family homes.
Will we move Manhattan back?
Not likely. In the case of major cities, diking and armoring will likely prevail in case of
major sea level changes.
A FINAL WORD
A new order of coastal scientists and engineers must develop new strategies in selecting
solutions to shoreline retreat from a broader menu of possible solutions. Each approach must
involve evaluating realistically the natural setting as well as the socioeconomic objective.
Application of standardized formulas, standardized models, and "one size fits all" engineering
has proven inadequate; it is unrealistic in the face of nature's chaos, as archaic as "one device"
shore-hardening structures. Old established ports and urbanizedlindustridized shorelines,
where the priority is protecting property, will still require seawalls and groins. Shore
hardening should be a nonchoice for most communities that wish to preserve recreational and
protective beaches. Soft solutions, particularly beach nourishment, should not be sold to the
public without their full knowledge of the required economic commitment and practical
feasibility, i.e., the option is expensive, requires a long-term commitment, and a continuous
future quality sand supply. The engineering community should apply their expertise to the
technology of relocation in which beaches can be conserved, buildings saved in many
instances,and the impact of future erosion reduced.
REFERENCES CITED
Chnastowski, M J , 1991. The building, deterioration and proposed rebuilding of the Chicago lakefront.
Shore and Beach, v.59, no.2p.2-10.
Hall, MJ., and Pilkey, OX.,1991. Effects of hard stabilization on dry beach width for New Jersey. Journal
of Coastal Research, v.7,no.3, p.771-785.
Kaufman, Wallace and others, 1985. National stfategy for beach preservation: Second Skidaway Institute of
Oceanography Conference on Amaica's eroding shorehe, proceedings; Savannah,GA, 11 p.
Kraus, N.C, 1988. The effects of seawalls on the beach: an extended literature review. .!oumal of Coastal
Research, Special Issue no.4, p.1-28.
Norris, W.,
1990. Sea cliff erosion: a major dilemma. CaliforniaGeology, v.43, no.8, p.171-177.
Pilkey, OH., and Clayton, T.D., 1987. Beach replenishment the national solution? Coastal Zone '87.
p.1408-1419.
Pilkey, OH., and Wright, HL.. III, 1988. Seawalls versus beaches. Journal of Coastal Research, Special
Issue NoA. p.41-64.
Smith, A.W.S., 1990. Discussion of: Pilkey, o.H.,1990. A time to look back at beach replenishment
(editorial). Joumul of Coastal Research, 6(1), iu-vii. And, Leonard, L.: Clayton, T.. and P i e y , O.H.,
1990. An analysis of replenished beach design parameters on US. east coast bamer islands, Journal of
Coastal Research, 6(1), 15-36. Journal of Coastal Research, v.6, no.4, p.1041-1045.
Tait, JJ.. and Griggs, G.B.,1991. Beach response to the presence of a seawall; comparison of field
observations. U.S. Army Corps of Engineers, U.S.AE. Waterways Experiment Station, Vidcsburg,
MS, o o n m report CERC-91-1.60p.
Proceedings of the International meeting (Nantes, 17-20 octobre 1991)
Special Issue
Coastal protection, International experiences and prospect
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The special issue, a 360 pagekbook, is now available (Write IGARUN BP
1025, 44036 Nantes Cedex 01 France). Price 55 US dollars or 300 French
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Payment at the order of M. L9agent comptable de IyUniversit6de Nantes
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TABLE DES MATIERES
Avant-propos (foreword)
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0, PILKEY et W. NEAL Realism in response to shoreline erosion problems :a call for a new world order.
.........pl-8
L1brosion cetibre, etudes de cas.
Case studies in coastal erosion
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P.P WONG CoastaI protection in Singapore.......................................................................................... p 10-15
W.J CLEARY - New Topsail inlet N.C, migration and barrier realignment :consequences for beach restoration ...... p. 16-30
K. ADAM Le littoral du gdfe du Benin, atout straegique ......................................................................... p. 31-41
M. MANSOUM La grande plage dlAgadir, pmenagement Cvolution et protection ........:...........................,.... p 42-49
M. DARMANE (Maroc) L10dyss6edu Kharg et Ies problbmes de protection du littoraI marocain entre Onalidia et
p . 50-58
Safi. ...............................................................................................................................................
P, SADDUL The impact of storm waves and economic activiites on the southern coast of Mauritius - an
p. 59-69
assessment.. .................................................................................................................................
M-T PROST et C. CHARRON L'6msion &&re en Guyane ......................
.
.
.
........................................ p 70-81
Y. SHUISKY The impact of artificial negative relief forms on the toad m e of seas. ..................................... p. 82-92
J. T MOLLER Management problems on Danish North Sea coasts. ............................................................. p. 93-98
C. CABANNE et A.MIOSSEC Un exemple de protection du littoral : la c6te de la Mer Noire entre Sotchi et
Batoumi............................................................................................................................................
p. 99-105
C.BONNOT-COURTOIS et L.R LAFOND Dynamique &mentaire du littoral de Sables dlOr les Pins (C6tes
dlAnnor). ..........................................................................................................................................
p. 106-115
C. YONI, B. HALLEGOUET et J.C BODERE Ouvrages de protection et artificialisation de la ligne de rivage
dans le pays Pagan (Fhistbe). ................................................................................................................ p. 116-124
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Des petits fonds du large aux dunes bordibres.
From foreshore to coastal dunes.
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K. SCHWARZER Exchange of sediment between beaches and bars after a beach nourishment ...........................p. 126-133
G. DE MOOR - The beach nourishment of Bredene - De Haan and its impact on beach morphoIogy and coastal
.
.
................................................. p.
evolution of the Belgian coast east of Ostend......................................
E . ANTHONY, P. JAGOUDET et S. PEREZ Gravel beach stabilization measures in the Baie des Anges, C6te
d' Azur (France). ................................................................................................................................ p.
E. BIRD The management of artificial beaches........................................................................................ p.
D. MOULIS, P. BARBEL, et M. RADULESCU Protection contre 1'Crosion des c6tes par des techniques
1Cgkres : I'exemple de la flkhe sableuse de la Gracieuse sur le littoral maiterraden franpis.. .................................. p.
B. HALLEGOUET. J.C BODERE et C. MEUR - Biian des expCriences de protection souple des littoraux
p.
meubles dans le massif annoricain. ..........................................................................................................
J.C BODERE, B. HALLEGOUET, C. MEUR, F. VICTOR et A. HENAFF - A propos d'initiatives
empiriques en matikre de renforcement des cordons littoraux : I'utilisation des produits de dragage et de dQroctagedes
ports de p k h e sud-finisteriens.. .............................................................................................................. p
N.P PSUTY et T.A PICCOLA - Foredune sediment budgets, Fire Island, New York - USA - 1982-1991. ................. p.
J.C BODERE, R.CRIBB, R. CURR, P. DAVIES, B. HALLEGOUET, C. MEUR, N. PIRIOU, A.T
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134-144
145-152
153-160
161-170
171-178
179-185
186-196
.
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WILLIAMS. C YON1 Vulnbrabilit6 des dums littorales : mise au point d'une mtthode d'tvaluation. itudes de
cas dans le sud du pays de Galles et I'ouest de la Bretagnc
...............................................................................
p. 197-203
La n a t u r e littorale. entre Ies modLles i t la gestion.
The Coast. from modeling to management.
.
.
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B BELLESSORT L'ingdnieur et les etudes d'amtnagement du littoral. &s moyens d'btude de la nature aux
modMes physiques et numQiqties.. ........................................................-.....--......-....................................
p. 205-213
G ROSSI, L BARITSE et A BLIVI Du d
e A la nature :I'exemple de la dte Togolaise............
'.............p. 214-225 .
C MOUTZOURIS .Observation of the post-consauction performance of the system of groins along an eroding
p . 226234
beach..............................................................................................................................................
L.R LAFOND Le b b n a g e m e n t du littoral Haut-Normand B Criel-sur-Mer (Seine Maritime)............................... p. 235-245
M LARCHER Protection du littoral I*& des "h~yaux....................................... .. ............................... p . 246251
H REGNAULT, P GOUERY et C KUZUCUOGLU .Protection du littoral. reconstitution de paysage :
simulations numtriques et pkvisions....................................................................................................... p. 252-260
J FOURNIER .La gbo-dcologie : une approche globde du systkme littoral et des'interactions socibti-milieu
naturel.L'exemple du littoral du Petit Tdgor (Finisere, France)....................................... .. .........................p. 261-267
J.J BLANC Une zone B risques : le littoral de la Camargue (delta du Rhbne). Evaluation du recul des plages et
p . 268-278
analyses pdvisionnelles....................................................................-.-............................................
F LEVOY
L'ttude
globde
concernant
la
dbfense
c o n e la mer du d6partement de la Manche : vers une nouvelle
..
pol~ttquede protection des c6tes...........................................................................................................
p 279-290
R PASKOFF .La cartographie prospective de I'bvolution du trait de cdte : un instrument indispensable pour
I'ambnagement des espaces littoraux........................................................................................................ p. 291-297
P LASCOSTES .De la recherche d'un proc6dd de &limitation du Domaine Public Maritime & une cartographie
d'exposition aux risques marins........................................................................................................ ;......p. 298-306
J.P PINOT .Fixer le plan ou g h r le profil l'exernple du Sillon du Talberv ......................................................p. 307-316
A.H MESNARD Centralisation et d6centdisation dans la politique publique du littoral en France....................... p . 317-321
C MEUR. J.C BODERE et B .HALLEGOUET .Les politiques de gestion des espaces naturels Iittoraux en
France :l'exemple de la Bretagne.............................................................................................................
p.322-333
Ch ANTONOPOULOS La protection du iittotal en Grke : aspect techniques. administratifs et financiers............p . 334340
A MIOSSEC .La defense du hait de t$te en France. un pmblhne de soci6t6...................................................... p. 341-348
R.W.G. CARTER Coast erosion management in the United Kingdom 1980-2000........................................ p. 349-358
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Quelques conclusions d u colloque (A MIOSSEC)
A few conclusions f r o m t h e meeting