INTRODUCTION

The coastal zones are the country's most densely populatedareas, including the Metropolitan Areas of Lisbon and Oporto.Between Braga and Setubal, the majority of the cities have apopulation density higher than 100 inh/km . The problems ofthe Portuguese coastal zones arise essentially from theconsequences of the dynamics of the coastal system, as well asthe type of use and management.

The Caparica -Espichel Coastal Arch (Figure 1), in thewestern coast of the Setúbal Peninsula, refers to the vast coastalarch reaching from Costa da Caparica up to the Espichel Cape.The evolution and occupation of this area is intimatelyconnected to the territorial processes on the LisbonMetropolitan Area (LMA), of which it is an integratedcomponent.

The development model of the LMA is an excellent exampleof coastal area under pressure, this basically being theeconomic, political and population concentration in the coastalareas of the country. With an extensive coastal line with 540 km(Atlantic coast, Tagus estuary, Sado estuary and Albufeiralagoon) the LMA has revealed itself as a dynamic factor of thenational economy with more than 60% of the total employmentin the mainland in the secondary and tertiary sectors.

Nevertheless, the consequent concentration of thepopulation, with more than 2,5 million inab. by 1991, and theexponential growth of the urban areas is by itself a complexterritorial phenomenon. The result has been obvious, translatinginto serious environmental problems, with direct implicationson lessening of the citizen's quality of life, with specialrelevance given to the occupation and loss of areas withgeomorphologic, fauna, flora or landscape interest, due to theirdirect and indirect impact.

The coastal “territory” is, by definition, the area wheremarine and continental influences merge and it should includean area over and underwater, thus being a zone wheretransversal exchanges should be kept in order not to risk loosingthe integrity of the coastal biophysical systems through anoverburden of their resilience limits and

2000).From this, one deducts that in the littoral territory a dynamic

2

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equilibrium exists, arising from the interaction of a multitude of

Journal of Coastal Research SI 39 1590 - 1593 ICS 2004 (Proceedings) Brazil ISSN 0749-0208

FERREIRA, J. C., 2006. Coastal zone vulnerability and risk evaluation: A tool for decision-making (an example inthe Caparica Littoral - Portugal). Journal of Coastal Research, SI 39 (Proccendigs of the 8th International CoastalSymposium), 1590 - 1593. Itajaí, SC, Brazil, ISSN 0749-0208.

The Caparica-Espichel Coastal Arch, in the Portuguese western coast (Setúbal Peninsula and Lisbon MetropolitanArea), has a diversity of biophysical systems and different forms of human use that translate into distinct evolutiondynamics, vulnerability and environmental risks. The area under study remains a remarkably representativeexample of the conflicts and problems arising from the antropic pressure over a coastal area rich in natural values,framed by a lack of efficient planning and land management. This paper presents a conceptual model for thedefinition and characterization of environmental risk and vulnerability in the coastal areas under anthropogenicpressure, aiming mainly at supporting the development of strategies and measures for coastal environmentalmanagement. The methods for evaluation of vulnerability and risk, in what concerns marine and continentalerosion, were developed with the use of the Geographic Information Systems, field work and the monitoring of theimpact of extreme phenomena, such as the storms that occurred in the 96/97 and 02/03 winter seasons. This workdeals with notions such as biophysical vulnerability, hazard and risk in coastal areas.

ADITIONAL INDEX WORDS: Hazard, evaluation, monitoring and environmental management methods.

ABSTRACT

Coastal Zone Vulnerability and Risk Evaluation: A Tool for Decision-Making (AnExample in the Caparica Littoral - Portugal)

J. C. Ferreira

Journal of Coastal Research Special Issue 39, 2006,

Dept. of Sciences and EnvironmentalEngineering (DCEA-FCT)New University of Lisbon,Campus da Caparica2819-516 Caparica, Portugaljcrf@fct.unl.pt

Centre for Geographical Studies andRegional PlanningNew University of Lisbon,Av. Berna 26-C

0 2,5 km

Almada

Sesimbra

C. Caparica

Espichel Cap

TagusEstuary

AtlanticOcean

Lisbon

LandscapeProtectedArea

Caparica -EspichelCoastal Area

Seixal

MAL Spai

Atl

anti

c

Figure 1 - Caparica - Espichel CoastalArch.

biophysical and socio-economic variables, the knowledge ofwhich (and data access) is quite unequal, because some of themare still unknown and others present themselves under differentshapes, of sometimes hard compatibility 1999).

This notion of vulnerability, based on the biophysicalsystems' resilience capacity, completes in a significant way theterritorial vulnerability, understood, by the definition of

(1984), (1990) or (1997 and 1999),as the degree of susceptibility to the loss of a certain element orgroup of elements by the territory namely populations, goodsand economical activities, when exposed to a natural or man-induced hazard, by introducing the biophysical component

and 2000).Also, hazard is consideredas the probability of occurrence of potentially destructivephenomena over a certain period of time and on a certain area

1999).

of the biophysical and antropic littoral

matching between the littoral biophysicaldynamics and the littoral antropic dynamics, allows thedefinition, in an integrated manner, of the littoral environmentdynamics. This, enables the identification and description of theareas vulnerable to certain types of hazards as well as theevaluation of the associated risks, either existent or potentialones. The identification and characterization of areas with ahigh vulnerability and biophysical risk is thus, the fundamentalbasis for the definition of strategies and environmentalmanagement tools, properly applicable and applied to a specificlittoral area.

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This work deals with notions such as biophysicalvulnerability, which should be understood as the degree ofsusceptibility of the biophysical systems to an irreversibledegradation, if its resilience capacity is overpassed( 1997, and , 1996). It isthus, assumed that the generalized and persistent evidence ofdegradation shown by a biophysical system are sure signs that ithas became incapable of naturally self-regulation.

Under this notion, a certain risk of a biophysical nature, orbiophysical risk, translates into a probability and is calculatedby the hazard (natural or induced) multiplied by the degree ofthe territorial vulnerability, including the vulnerability of thebiophysical systems.

The hazard determines the probability of the riskmanifestation (on a certain scale), while the vulnerability is aconditioning of the risk degree. It should be stressed that the risknotion always implies material or human losses (quantifiable)on a certain area, over a defined time frame. Thus, an area withhigh vulnerability may not necessarily translate into an area ofhigh risk.

The model depicted below (Figure 2) aims at summarizingthe fundamental variables for vulnerability and biophysical riskevaluation on coastal areas. As expected, this evaluationrequires the knowledge of the interaction of a high number ofbiophysical and socio-economical variables, to which oneshould add the management tools that allow thecharacterization

The proposed methods for vulnerability and biophysical riskevaluation on littoral areas incorporate, as previouslymentioned, an elevated number of components and variables.We will only address vulnerability and risk assessment relatedto erosion phenomenon. In fact, erosion, either marine orcontinental, is one of the main factors responsible forenvironmental deterioration and the consequent loss ofbiodiversity in the studied area. Since all the informationproposed in the model was not available on a digital format wechose to characterize the variables, found fundamental for theassessment of the vulnerability to hydric (continental) andmarine erosions, through two distinct methods1999):

a) for the continental variables: multi-criteria assessment,considering the data to handle and the extension of the area,which allowed the ranking of information of different types andsources, based on an evaluation expressed in values andmodifying factors, according to the intensity and the degree ofimportance of each of the variables;

b) due to the lack of data and detailed studies on the littoraldynamics of the studied area, for the marine variables, we chosethe analysis of the morphogenic effects of a series of stormepisodes, from December 1995 to January 1996. To bettercharacterize the storm episodes and their consequences, wehave studied the weather conditions and corresponding wavesas well as the field record of the erosion effects registered in thearea.

Starting with the classification and matching of the chosenvariables, according to the criteria described by(1999), we have reached different levels of biophysicalvulnerability. The calculation of different groups of risk has soiluse as its basis, this last one understood in the sense of theexistence, and distinction of, territorial segments that aresocially referenciable. Thus, we have introduced in thisanalysis, through an indirect path, the socio-economical factors(the ones bearing territorial expression) that can stress orattenuate both human and material damages and losses.

Due to the high number of variables under consideration ithas been necessary to use a Geographic Information Systemwhich, through a georeferenced database, has allowed asystematic and efficient matching of information as well as theelaboration of different settings. Below (Figure 3) an examplecan be found of the referred variables as well as the achievedresults 1999).

The results from the application of the devised model clearlyreflect, the used methods and its clear dependence from theconsidered variables and corresponding classifications. Puttingthe results into a spatial model, allows for a clearer view of thedifferent patterns of the studied variables behaviour respectiveto erosion hazard and erosion risk. As shown in Figure 4, thehazard and risk to erosion are higher along the coastline andalong the fossil cliff, displaying a strong subjection to thelithology, slopes and soil use.

From the study of the consecutives episodes of storm duringthe timeframe of December 1995 to January 1996, it has beenconcluded that the total area of the Caparica-Espichel CoastalArch has been affected, in an identical form, by a tidal wavingcharacterized by great heights as well as total energy (heightsreaching sometimes as high as 9m). This has been due, duringsome periods, to the storm surge effect), causing the important

RUST ILLENBERGER

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METHODS

RESULTS AND ANALYSIS

dynamics. The data

Coastal Zone Vulnerability and Risk Evaluation

Journal of Coastal Research Special Issue 39, 2006,

Figure 2. Conceptual model for vulnerability and risk evaluation(biophysical) of the Portuguese coastal areas (F , 1999).ERREIRA

Meteorology

Oceanography

Morphology

Hydrograohy

Geology

Vegetation

Land Use

Demography

Land Management

Plans

Coastal ZoneManagement Plans

Windatmospheric pressure

Precipitation

Swell / currents

Altimetry

Bathymetry

Aspects

Slops

Density Hierarchy

Neo-tectonics (faults)

Lithology Permeability

Density / Type

Population density

Urban / open spaces

Urban density (building)

Ecological Reserve

Agriculture Reserve

Nature/forest

Agriculture

Urban

Future urban areas

Master Plan(Restrictions)

Master Plan(L. Manag.)

Antropicdynamics

Potentialscenario

Coastal dynamics

Biophysicaldynamics

Geomor. / land instabilityhazards (ex. soil erosion)

Risk

Vulnerability to aquifercontamination

Vulnerability to floods

Vulnerability to geological/tectonic hazards

Other hazards

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Journal of Coastal Research Special Issue 39, 2006,

morphogenic action associated with these storm episodes1999).

The observed weather conditions have equally caused astrong storm on land (abundant rains) with severe littoralrepercussions.

However, the field monitoring of the storm effects has shownthe fact that, not only do the different littoral biophysicalsystems have different responses, as obviously expected, butalso the same system can prompt a significantly differentresponse when faced with the very same phenomenon.

Considering only the different beaches systems frontal dune(littoral plains) and cliffs, namely the fossil cliff, four majortypes of erosion mechanisms triggered by the studied stormepisodes, can be found:

1.Marine erosion, which has strongly affected the dune ridge,creating cliff-like profiles along the dune front of the systemreaching as high as 6 m, which caused severe beach erosion. Inthe beach-cliff system the wave strength has destabilized,through undercut, a large part of the alluvium which fossilizesthe coastal front as well as the active cliff, causing vast erosion;

2.Marine erosion by oceanic overflow, recorded in all of themain paths through the dune ridge up to the beach, clearlyshowing the system's vulnerability, since all the discontinuitiesof the dune ridge of antropic origin are taken advantage of;

3.Hydric erosion (mass movement and soil erosion)responsible for gully phenomena in the cliff system, fossil oractive;

4.Mixed erosion (with simultaneous marine and hydricorigins).

Through the analysis of the morphogenics effects of thestudied group of storm episodes it was then possible to knowwhich of the littoral systems are more vulnerable to the marineerosion. Neverthless, the fossil cliff has a high vulnerability tothe erosion risks, namely the mass movement hazards,jeopardizing human lives and accounting for major losses.

The behaviour of the above mentioned systems, reveals thatthe vulnerability to marine erosion is strongly dependent on thelithology (loosen sands from the frontal dunes ridges and less

consolidated materials from the cliff), on the Arch location (asbelieved that in a western storm, the energy arising from thewaves concentrates mainly inside the coves) as well as on thedegradation due to its inadequate use (areas of discontinuity ofthe frontal dune arising from the opening of paths to the beach).

As to the risk of erosion, calculated by the matching of thebiophysical vulnerability and the soil uses, an higher extensionof risk areas, considering the former identified vulnerable areas,has been found, because areas previously classified as with lowvulnerability now clearly present an elevated risk of erosion(marine and continental), namely the urban areas.

This way, integrated in the LMA, the studied area is asignificant example of the problems and conflicts arising fromthe antropic pressure over a littoral area, with rich natural assets,as well as the lack of an efficient territorial management andplanning and the inexistence of an environmental managementcapable of allowing a sustainable development of the coast,with clear consequences for the economy of this region. Thestorm episodes which took place in the last Winters (December2000 and January 2001, February 2003 and January 2004),responsible as they were, for a generalized erosion in all of thestudied area, specially with unrecoverable damages in the northsector of the dune ridge and fossil cliff, have demonstrated onceagain the need to incorporate more studies on vulnerability andbiophysical risk on the Coastal management Plans (centraladministration) as well as the Master Plans (localadministration).

Despite its relative simplicity, the presented methods, havedemonstrated a strong efficacy, in the identification of theproblematic territorial units, because it allows a clearidentification of the areas with a high hazard and risk. The areasthus identified by (1999), as the most vulnerable andmore subject to a stronger erosion risk, are exactly those thathave revealed themselves as more affected by erosion causing

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DISCUSSION AND CONCLUSIONS

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enormous financial damages and jeopardizing human lives.(Figure 5)

Ferreira

Figure 3. Some of the referred variables, 1 Slops; 2 Lithology;3Altimetry and hydrography; 4 Coastal erosion;5 Vulnerability; 6 Fluvial and coastal erosion; 7 Master plan;8 Population density; 9 Land use; 10 Risk (F , 1999).ERREIRA

N

0

Hazard and Risk

Low

Moderate

Hight

Extremely Hight

Maximum

Risk

C. Caparica

F. Telha

Bela Vista Beach

C. Vapor

Foz do Rego

Albufeira

Espichel Cap

P. Apostiça

C. Malha

Aroeira

Hazard

Raposeira

São João Beach

Lagoon

3 km

Figure 4. Hazard and risk on the Caparica-Espichel Arch(F , 1999).ERREIRA

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Considering that this is an expedite method and easy to use,we find it to be a suitable, basic instrument for the definition ofthe areas that are more prompt to biophysical risk and the resultsfrom its proper use could allow for an improvement of the landmanagement aiming at a new model of planning, efficient andsustainable 1990) of a sparse resource such as the coastalterritory.

We would like to extend our thanks to the PortugueseFoundation for Science and Technology (FFCT) of thePortuguese Administration for Science and Higher Education(Minisntério da Ciência e do Ensisno Superior), for providingfinancial support to this research under the Centre forGeographical Studies and Regional Planning (http://e-geo.fcsh.unl.pt) which allowed the development of this project.

J. C., 1999. Vulnerabilidade e Risco Biofísico emÁreas Costeiras. O Arco Litoral Caparica - Espichel,Dissertação de Mestrado em Geografia Física e Ambiente,Universidade de Lisboa, (Lisboa), p. 148.

M., 1997. Vulnerabilidade e Gestão dos SistemasDunares. O Caso das Dunas de Mira. Dissertação deMestrado em Ordenamento do Território e PlaneamentoAmbiental, Universidade Nova de Lisboa (Monte daCaparica) p. 104.

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ACKNOWLEDGEMENT

LITERATURE CITED

FERREIRA, J. C., ALVES, TAVEIRA PINTO

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LARANJEIRA, M., PEREIRA, A., WILLIAMS

PANIZZA,

REES,

RUST, ILLENBERGER,

VARNES,

F. and , F., 1997.Vulnerability and Risk in The Portuguese Coastal Zone - amethodology of analysis, COASTLINES'97 proceedings -6th Europeaan Union for Coastal Conservation, Napoles.

J. C. and M. M, 2000. Avaliação daVulnerabilidade e Risco Biofísico em Áreas Litorais SobPressão Antrópica. Contributo Metodológico para umaGestão Ambiental, GeoInova - Revista do Dep. Geografia ePlaneamento Regional da Universidade Nova de Lisboa,Nº2 /2000, FCSH/Universidade Nova de Lisboa (Lisboa)pp.153 - 170.

, A., 1999.Comparison of two checklist methods for assessment ofcoastal dune vulnerability. Boletín del Instituto Español deOceanografía, nº15, in press.

M, 1990. Geomorfologia applicata. Metodi diapplicazione alla pianificazione territoriale e allavalutazione d'impatto ambientale. La Nuova ItaliaScientifica, (Roma), p. 342.

J., 1990. Natural Resources: Allocation, Economics andPolicy, Routledge, (London), p.499.

I. and W., 1996. Coastal Dunes:Sensitive or not?, Landscape and Urban Planning, 34,pp165-169.

D., 1984. Landslide hazard zonation: a review ofprinciples and practice. UNESCO, Paris.

Journal of Coastal Research Special Issue 39, 2006,

Coastal Zone Vulnerability and Risk Evaluation

b

a

c

Figure 5. Dune ridge and fossil cliff several erosive episodes,after the use of the identification methods (see also Fig. 4). a) S.João Beach( (Costa da Caparica), February 2003 destruction ofthe dune ridge, causing an increased risk to camping parks andother buildings. b) S. João Beach (Costa da Caparica), January2001 dune ridge erosion and destruction of the beach facilitiesc) Raposeira (fossil cliff), January 2004 landslide withdestruction of several houses.

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