Project part-funded by INTERREG III C West Zone
SOCIAL MULTICRITERIA EVALUATION OF ALTERNATIVE
SOLUTIONS FOR COASTAL EROSION:
THE CASE OF THE LIDO OF SÈTE
Component 3: Valuating the shoreline
Messina Project
February 2004
FOREWORD
The preparation of this report has been undertaken as part of the Component 3 “Valuating shoreline” of MESSINA (Managing European Shoreline and Sharing Information on Nearshore Areas). This initiativewhich ispartly-funded by INTERREG III C West Zone of the European Union, involves different partner institutions andit runs for the period Jan 2004- Dec 2006. This report has been realised by the Institute of Environmental Sciences and Technology of the Autonomous University of Barcelona.
The following people have contributed to this study: Coordination:
— Dr. Jordi Serra (Associated professor of the Institute of Environmental Sciences and Technology, University Autonomous of Barcelona).
Authors:
— Gonzalo Gamboa (Institute of Environmental Sciences and Technology, University Autonomous of Barcelona)
— Adeline Komen (Institute of Environmental Sciences and Technology, University Autonomous of Barcelona)
— Elisabet Roca (Institute of Environmental Sciences and Technology, University Autonomous of Barcelona)
Any comments and additions will be welcome at the following address: e-mail: gr.eurosion@uab.es
TABLE OF CONTENTS
1 EXECUTIVE SUMMARY ... 4
2 SMCE FOR COASTAL MANAGEMENT ... 6
2.1 MULTICRITERIA EVALUATION ... 6
2.2 Theoretical basis of SMCE... 6
2.3 SMCE PROCESS... 8
3 THE PROCESS ...10
3.1 Problem and stakeholders identification...10
3.1.1 Context. The Lido of Sète...10
3.1.2 Coastal erosion phenomena as a problem ...20
3.2 MULTI-CRITERIA STRUCTURE ...25
3.2.1 Stakeholders preferences ...25
3.2.2 Alternatives...31
3.2.3 Evaluation criteria...35
3.2.4 Criteria scoring ...39
3.3 Selection of the Evaluation tool ...52
3.4 Comparison of alternatives ...54 3.4.1 NAIADE analysis...54 3.4.2 Thresholds definition ...54 3.4.3 Regime analysis ...56 4 CONCLUSIONS ...58 5 References ...60 ANNEX I. Map of coastal erosion trends
ANNEX II. Maps of Alternatives
ANNEX III. Results of REGIME method
1 EXECUTIVE
SUMMARY
This report describes a study case performed in the frame of the component 3 “Valuating shoreline” within the Messina project, Interreg III-C West. The aim of the Component 3 is to review concrete examples of economic analysis methodologies applied to shoreline management policy inside and outside Europe.
This report presents the application of a Social Multicriteria Evaluation (SMCE) in the study area of the lido of Sète (Southern France).
The lido of Sète, a narrow strip of land separating the lagoon of Thau and the Mediterranean Sea, has become very vulnerable to coastal erosion and sea level rise. Many activities developed on this land (housing, vine growing, tourism installations and high ecological value areas) as well as fishing activities inside the lagoon are at risk of serious economical, social and environmental consequences. At the end of the nineties local authorities have started a process to search for a long-term solution. Currently, this solution implies moving backward hard infrastructures (e.g. coastal road) and restoring the dunes to increase the system’s resilience against erosion.
In order to evaluate this situation, where “facts are uncertain, values in dispute, stakes high and decisions urgent” (Funtowicz and Ravetz, 1991, 1994), a combination of participatory process and multi-criteria evaluation has been applied, based on the framework of Social Multi-Criteria Evaluation (SMCE), developed by Munda (2004).
SMCE can be roughly described as a methodology for decision-making process. After gathering the perceptions, opinions and objectives from different social actors, the information is structured in a multi-criteria evaluation framework, following several steps: - The identification of the problem at hand, and the isolation of the relevant stakeholders; This task is done by means of an institutional analysis, i.e. a review of official documents, newspapers and so on. By means of participatory techniques (focus groups, in–depth interviews and meetings) it is possible to have an approach of the problem (in this case, coastal erosion) from several points of view. Participatory techniques are also useful to identify other social actors who haven’t been considered yet. In Sète, the beach erosion is not the only problem, camping cars parked along the road and dune system degradation are other concerns.
- The creation of alternatives to solve the problem; Stakeholders’ preferences are an important input for this task. On this basis, four main alternatives (Business as usual, hard engineering, medium-displacement of the road and road displacement) have been established with small variations (location of cycling track and parking areas).
- The criteria definition, which relies on and represent the social actors’ preferences. The following criteria have been considered: security, long-term effectiveness, investment costs, maintenance costs, visual impact, impact over marine environment, fragmentation, regional impact.
- Criteria valuation; after valuating the criteria, it is possible to structure the information within an impact matrix.
- Selection and application of the evaluation tool; according to the characteristics of the problem at hand, e.g. types of criteria, use of weights, and so on, the multi-criteria
technique is selected. In this work, two methodologies have been used trying to fulfil the desired characteristics for a SMCE: Naiade (Munda, 1995) and Regime (Hinloopen E., Nijkamp P., Rietveld P.1983).
- Presentation of results and feedback to the stakeholders in order to validate the work performed.
Finally, this report concludes reviewing the lessons learnt from the study case and highlighting advantages and constraints for future uses of this methodology.
2 SMCE FOR COASTAL MANAGEMENT
Social Multi-Criteria Evaluation (SMCE) can be roughly described as a methodology for decision-making process. After gathering the perceptions, opinions and objectives from different social actors, the information is structured in a multi-criteria evaluation framework. 2.1 MULTICRITERIA EVALUATION
Multi-criteria evaluation can be described as the comparison between different alternatives aimed to solve a defined problem. This comparison is made contrasting the performance of each alternative under different perspectives (criteria).
Table 1 shows a multi-criteria problem structured in the impact matrix. Here the m alternatives (A1, A2,… Am) have the different performances (gi(Aj)) according to the n criteria (C1, C2,… Cn).
Table 1. Multi-criteria structure Alternatives Criteria A1 A2 … Am C1 g1(A1) g1(A2) … g1(Am) C2 g2(A1) g2(A2) … g2(Am) … … … ... … Cn gn(A1) gn(A2) … gn(Am)
For example, when we buy a pair of shoes, the alternatives are boots, sport shoes, moccasins, sandals, and so on. On the other hand, the price, if they are comfortable, the colour, and other features, are the different perspectives (criteria) for the selection of the “right”1 pair of shoes.
Multi-criteria evaluation has been normally used for modelling the preferences of the decision makers, i.e. analysts and decision makers define alternatives and criteria based on their perception of the problem for further evaluation of the alternatives and selection of the solution. These kinds of closed approaches have to be shifted, and SMCE is an attempt to do that.
2.2 THEORETICAL BASIS OF SMCE
Problems of our times are characterized by deep complexity2. Moreover, human systems are reflexively complex3, and they can continuously add new relevant attributes that should be considered when explaining and describing their behaviour. Then, it is necessary to move from focusing on the quality of the results to focus on the quality of the process (the need to move from substantive to procedural rationality (Simon, 1976))4.
1“Right” is understod as fitting for purpose.
2 A system is complex when the relevant aspects of a particular problem cannot be captured using a single perspective
(Funtowicz et al., 1999; O’Connor et al., 1996).
3 The presence of “awareness” and “purpose” make human systems reflexively complex.
4 According to Simon (1976), it can be distinguish between the rationality of a decision independently in the way it was taken
In addition, the existence of different levels and scales at which a hierarchical system can be analyzed implies the unavoidable existence of non-equivalent descriptions of it (Giampietro and Mayumi, 2000; Giampietro 2004). For example, in generating evaluation criteria (e.g., in evaluating the impacts of changing the position of a road for regenerating natural spaces in a coastal region, who are the relevant social actors to interact with? The inhabitants of the coastal region, the potential users of the beach in urban areas and even the ecological preservationists all around the world might sound reasonable answers) or in computing the impact scores (e.g. a contamination indicator has to be computed locally, or should it be computed at a larger scale?)
The issue that more than one representation of a system from different scientific fields can exist (epistemological multiple identity) entails what Munda (2004) calls Technical Incommensurability5. In addition, because human systems are reflexive complex systems (they learn through the time), there exist multiplicity of legitimate values and aims in society (ontological multiple identities), which implies Social Incommensurability.
Technical incommensurability could be faced by means of multi/inter-disciplinary work, and Multicriteria Evaluation offers a good framework to do that. And to face Social Incommensurability the process has to be as participative as possible, and take into consideration different points of view into society6.
In this proposed methodology transparency is an essential feature to guarantee the quality in any study based in science for policy, allowing peer reviewing to all the social actors. Since different representations of the situation exist, there is a need to show all the assumptions taken into consideration. Multi-criteria methods present the impacts in the original form (unit of measure) without reduction to a single unit of measure (like Cost-Benefit Analysis and Cost-Effectiveness Analysis do).
Then, SMCE implies a multi/inter-disciplinary approach, a process as participative as possible and transparency as one of the fundamental pillars.
When using science for policy there are possible long term consequences that we don’t know. Additionally, we face problems where “facts are uncertain, values in dispute, stakes high and decisions urgent” (Funtowicz and Ravetz, 1991, 1994). In this case, a bidirectional flow of information between science and society is crucial. Scientists cannot provide any useful input without interacting with the rest of society and the rest of the society cannot perform any sound decision making without interacting with the scientists (Munda, 2004). In a SMCE framework science for policy implies the scientific responsibility towards the whole society and not only to the decision makers. On the other hand, the issue that public participation is implied does not entail that the decision makers and the scientific team have no responsibility of the policy actions or decisions adopted.
it t
decision process itself). “A body of theory for procedural rational y is consistent wi h a world in which human beings continue
to think and continue to invent: a theory of substantive rationality is not” (Simon, 1976).
5 Martinez-Alier et al. (1998) stands that weak comparability implies incommensurability i.e. there is an irreducible value conflict
when deciding what common comparative term should be used to rank alternative actions
6 One of the implications of scale on multi criteria evaluation is that to reach a ranking (or a set of rankings) of policy
alternatives there is the need to decide previously what is important for different social actors and what is relevant for the
Finally, in SMCE, ethics matters. Since ethical positions, e.g. deriving weights, may lead to different rankings, the assumptions used have to be transparently expressed. Or regarding the participation process, some social groups could be excluded or with less bargaining power (future generations for example), but this does not imply that their positions or views have to be excluded in the analysis.
2.3 SMCE PROCESS
The ideal SMCE process is shown in Figure 1. The process is presented in a linear structure to facilitate its comprehension. But in real cases some of the steps overlap each other, and a cyclical procedure is always advisable.
Figure 1. The theoretical problem structuring in a SMCE process
Second round of participatoryprocesses.
Creation of alternatives and evaluation criteria Institutional analysis
Focus groups, in-depth interviews, meetings.
Problem identification
Stakeholder analysis of the results
Selection of the MCDA technique Identification of stakeholders
Model application Criteria valuation and Preference
elicitation
As it is shown, the first phase of the process is the identification of the problem at hand, and the isolation of the relevant stakeholders. At the beginning, this task is done by means of an Institutional analysis, i.e. a review of official documents, newspapers and so on.
Besides recognizing some involved social actors, the problem is defined. By means of participatory techniques7 (focus groups, in–depth interviews and meetings) and reviewing technical information it is possible to have an approach to the problem (in this case, coastal erosion) from several points of view. Participatory techniques are also useful to identify other social actors who haven’t been considered yet.
7 Participatory techniques mean contact with several social actors (citizens, associations, institutions, technicians, scientists,
The creation of alternatives to solve the problem is the next step. Stakeholders’ preferences are an important input for this task in order, for instance, to avoid social unconformity. As it was said before, the
According to the characteristics of the problem at hand, e.g. types of criteria, use of weights, and so on, the multi-criteria technique is selected the multi-criteria technique. After this, the model is applied and the results have to be returned to participants.
It is very important to have in mind the idea that all this methodology is flexible enough to be adapted to the context in which it is applied.
Next section presents this method applied to a practical case, a project aiming to face coastal erosion by restoring the dune system and the beach in the Lido of Sète (southern France) and moving the coastal road backward.
3 THE
PROCESS
In the previous section the Social Multi-criteria Evaluation process was shortly explained. In this section the case study carried out by the ICTA/UAB group in the Lido of Sète is presented. The organisation of this report follows the SMCE structure presented in Figure 1. Firstly, a description of the context is given, the Lido of Sète, its physical and socioeconomic environment, the legal and institutional context, and the identified social actors. This task is done based on the information gathered in participative activities and some documents reviewed (for instance, diagnosis reports).The aim of this part is to have a wide perspective of the context.
Then, the problem is structured in a multi-criteria fashion, i.e. the alternatives to solve the problem of coastal erosion, land uses in the Lido of Sète and the criteria for the comparison and evaluation of the alternatives are presented.
Finally, the last part of this report presents the multicriteria evaluation and the sensitivity analysis of the results. The results of the feedback information to the stakeholders are also explained.
3.1 PROBLEM AND STAKEHOLDERS IDENTIFICATION
This section presents the collected information related to the context in which the case study is carried out. First, the information concerning the physical environment, the natural driving forces of the system, the shoreline evolution and coastal erosion trends are presented. Then, the legal and institutional context of the lido is described, following with the review of the land uses of the lido. Finally, coastal erosion phenomenon is presented as a risk, considering the state of awareness and the proposed solutions.
After this, we will have enough information to understand the different positioning of the stakeholders, to structure and present the problem in a multi-criteria way.
3.1.1 Context. The Lido of Sète.
The Lido of Sète can be described as a narrow strip of land that separates the lagoon of Thau and the Mediterranean Sea (See Figure 2). This 12 kilometres length band of dunes and sand is located between Marseillan and Sète, in Southern France. Among about thirty costal lagoons in the Languedoc-Roussillon region, the lagoon of Thau is the largest (75 km2) and the deepest.
The permanent population of the catchment’s area of Thau, which has an average density of 120 hab/km2, is 80.000 inhabitants from which half are from the commune of Sète. The inhabitants number increases of 50% between 1954 and 1999 and follows an exponential growth since the end of 1960.
Many activities are developed on this land. The beach is a much-concurred site during summer time. The coastal road, next to the beach, is the main transport connection between both sides of the barrier spit, and it is also used as parking site for visitors.
Economic activities like vine growing and a camping site are located on the lido. The vineyards’ land is crossed by the railway, and the camping is located between the coastal
road and the railway track. Tourism is particularly developed in this area. Marseillan, Balaruc-the-Baths, Sète and Agde are tourist centres. In summer, due to tourism pressures, the population raise up to 130.000 inhabitants and can be multiplied for 8 in Marseillan and 1,2 in Sète. The hostelling capacity passed from 43.560 beds in 1968 to 75.115 beds in 1999 (La Jeunesse, 2001).
It is possible to find some “natural” environments, like the dunes and the wetlands, which are the target for restoration in the administration’s plans.
Lagoon of Thau Sète’s lido Marseillan Sète Spain Italy France
Figure 2. The Lido of Sète
3.1.1.1 Physical description and natural driving forces of the system
The study area is formed by three sedimentary series recently constituted (from the BRGM geological chart): Jurassic limestones in the Mount St. Clair (rocky shores), modern alluvial sediments, with a recent barrier spit, also known as lido in the Thau lagoon (sedimentary shores) and basalt flows and tuffites in Cap d’Agde (rocky shores).
The emerged body (barrier spit) is formed by 20m of sand and silt, which lie over a conglomeratic basement. The upper fraction of the sedimentary body is constituted by muddy sands and silt of 1-2m thick, lying over brown sands and under a thin layer of fine sand, which can be easily transported by wind. The submerged sediments are characterized by fine sands, of approximately 1m thick in the submerged sandbars.
The Lido of Sète is a typical Mediterranean sedimentary coastal system, which can be divided into three compartments in close relation: the nearshore (submerged part), the shoreface (intermediate part) and backshore (terrestrial part).
The nearshore bottom in front of the Lido of Sète is characterised by the presence of a set of longshore bars, parallel to the shoreline. South of Marseillan, three longshore bars have been identified: a distal bar at -4m depth, a proximal bar at -2m and the shoreface. In front of the Lido of Sète the sea bed present only two bars: the distal one, which is a
prolongation of the aforementioned, and the proximal one, close to the shoreline. The progression of the bars is closely related to a sequential dynamics, by a succession of deposits over the bar slopes (E. Akouango, 1997).
Figure 3. Topographical map of the Lido of Sète (Urbanis, 2003).
The upper limit of the nearshore is the breaking zone, where shoreface begins. The terrestrial part is the single or multiple functional dune strips, a true barrier for marine stormwaves, which are separated from the fossil dunes by foredune basins.
The sedimentary movements, which produce variations in the beach profiles, are the resultant of the action of the hydrodynamic factors. These factors comprise the waves and wind, which are the most important, and with minor importance the tide-generated currents and sea level rise.
The wind is an essential morphodynamic factor of the Mediterranean coastlines, responsible of the dunes’ formation. In the area of the Thau lagoon, the most important wind directions are NNW (36% ), NE (15%.), SE (15%).
Figure 4. The dunes of the lido
The mean eolian transport in the site of Sète (BCEOM, 2000) is about 250m3/m/yr, based upon observations made in the period from 1978 to 1983.
Thus, the functioning of these systems is based upon two dynamic factors: the south-eastern storms and the land winds. The first pushes the sediments hold in the submerged system onto the backshore (or conversely, depending on the capacity of energy absorption of the beach), and the second returns the sediments to the beach, hence restoring the shoreline.
The Mediterranean Sea is a micro-tidal system with variation of 0.33 cm. in Marseillan port. The data from tide gauges and satellite observations show that the mean sea level raised 15cm since the beginning of the 20th century, at a mean speed of 1.5mm/yr.
The resultant of these processes is the coastal sediment transport, which is a longshore drift running from northeast to southwest, with an average volume of 20,000 - 40,000m3/yr
A. Shoreline evolution and coastal erosion
Apart from the evidence, several studies reveal (Barusseau, 1996, Certain, 2002, BCEOM, 2000) that a clear deficit in sedimentary balance exists in the Lido of Sète. From 1954 to 2000 the Lido lost a total surface of 45 ha of beaches, which means a media of 1 ha per year (BCEOM, 2001). A deeper analysis shows that situations are different depending on the coastal sector (See Annex I):
— Almost 48% of the shoreline between Sète and Cap d’Agde, presents a state more o less in equilibrium or a light increase of the wideness of coastal profile.
— The northern sector of camping du Castellas, which corresponds with the zone of weak wave energy, is stable and accompanied by low dune system degradation in comparison with eroded sectors.
— Erosion sectors which extends to 9 km of shoreline distributed in 3 homogeneous areas: a) From PK 30 to PK 32.8: From the beach in front of the Triangle of Villeroy to the winery. In this sector, erosion has been revealed very active, where maximum shoreline retreat (50m in 50yrs) is observed.
b) From PK 34.2 to 37: From southwards of the winery to the northern limit of the camping. c) From 42.1 to 45.1: From the Marseillan port to the Ambonne Port. The southern sector suffers strong erosion, with a maximum retreat of 30 m. in 50 yrs southwards of Marseillan Plage.
These sections have similar characteristics: affected by high-energy waves, backward movements of the shoreline and diminution of the beach surface, degradation of the dune system and infrastructure in the high beach.
3.1.1.2 Legal and institutional context
Regulations concerning the Lido of Sète are a superposition of diversity of legislations and plans at different administrative levels. This section gives an overview of the legal framework affecting the coastal zone under study and the institutional context.
In France, the most important legislation affecting coastal management is the planning law, which is supervised by the Ministère de l’Equipement, des Transport et du Logement, whose responsibilities also include the administration of navigable waters. Other national government departments with functions in the coastal zone are the Ministère de l’Aménagement du Territoire et de l’Environnement (responsible for environmental protection and nature conservation) and the Ministère de l’Agriculture et de la Pêche (responsible for agriculture and fisheries). There are five levels of regional and local administration below the national government, of which the régions, départements and communes are involved in environmental management. There are also national agencies, including the Conservatoire du Littoral. At a National level the Organisation responsible for decision-making with respect to coastal protection is the Ministère de l’Environnement at a regional level the Prefecture, DIREN, Mission littorale (representing the environment), and at a Local level the Mairie (Tow Councils), Associations…
The coastal protection measures are at a national level through the Loi Littoral, at a regional level the “SMVM” Schéma de Mise en Va eur de la Mer and the Mission Littorale are found. The regional authorities (Préfet Maritime) are in charge to control the shoreline erosion. l
A. General regulations
Littoral Law and Public Maritime Domain
The law n°63-1178 of 28th November 1963, defines the Maritime Public Domain as: the bed and subsoil of the territorial sea (the stripe up to 12 nautical miles), foreshores and future accretions, and lands artificially reclaimed from the sea.
The Loi Littoral8, which was passed in 1986, inserts national provisions on coastal planning that must be observed by communes when preparing their plans. In particular, urban expansion is restricted to the vicinity of existing developments, and, within urban areas, construction is prohibited in a coastal strip extending 100 meters from the landward limit of the shore. Other requirements are the interruption of urban development by natural spaces, the maintenance of public access to the shore and the protection of sensitive sites. In addition, new transit routes must normally be located at least 2,000 meters from the shore.
The precise delimitation of the shore may be administratively determined by the State. In order to prevent private acquisition of this area, the law stipulates that Public Maritime Domain is inalienable, it doesn’t prescribe and it is non seizable.
Particular prescriptions of the departmental document of the Loi Littoral defined for the Lido of Sète are:
— Express of interest for natural conservation of this area.
— Salt mining and wetlands are considered sensitive spaces and are prohibited for new urbanization.
— Sea and lagoon shorelines up to 100 m can not be urbanized as they are Public Maritime Domain.
— The domaine of Villeroy is recognized as urbanized space.
Le Schema Directeur d’Amenagement et de Gestion des Eaux Rhône Mediterranée Corse (SDAGE Rhone Mediterranée Corse).
The Comite de Bassin elaborates with the decisions of the Regional and the General Councils (Conseils Régionaux et Généraux) the Schéma Directeur d'Aménagement et de Gestion des Eaux (SDAGE) it fixes for each hydrographical basin, or group of bassins, the fundamental orientations of an equilibrated management of water in quantity and quality. The SDAGE also defines the limits of the small basins corresponding to the hydrographic units.
The plan, which was adopted in 1996, is a basic framework for Rhone basin water management.
Main prescriptions of this document for the area under study are: — Ecological interest of this sector
— Economic interest of the Thau lagoon
— Objective for improving lagoon water quality
Le Schema de Mise en Valeur de la Mer de l’Etang de Thau et de sa Façade Maritime (SMVM)
In 1983, the option of development plans for the sea and adjacent areas was introduced (schémas de mise en valeur de la mer (SMVM)). These plans, which are adopted by the Ministère de l’Equipement, des Transports et du Logement on the submission of the Préfet du Département, are legally superior to sectorial, territorial and local plans. The SMVM is predominantly a marine planning mechanism, whereas the focus of the Loi Littoral is primarily terrestrial. Although the relationship between them is not entirely clear, together they provide a potential statutory planning framework for the whole coastal zone.
The SMVM de l’Etang de Thau et de sa Façade Maritime was approved by decree on April 20th 1995.
The general prescriptions of the SMVM are:
— Fishing and aquaculture are the principal vocation of the lagoon, so as water quality and facilitate the accessibility for the professionals should be maintained.
— The uses must be compatible with environmental protection and biological equilibrium. Preservation of hydraulic exchange areas, shoreline protection against erosion and rehabilitation of degraded sites are priority actions.
— The construction and urban settlements should take into account environmental protection and biological equilibrium. The plan gives preference to urban development close to the existent village than along the coast.
— There are no special recommendations for industry, port and commercial activities. — Tourism and leisure should take into account environment sensitivity
The SMVM suggests maintaining agricultural vocation and pursuing two type of actions for the global protection of the shoreline:
— Defence against coastal erosion — Rehabilitation of the dune system
The SMVM proposes the displacement of the road:
“The deviation of the National Road “RN 112” will, in the long term, make it possible to be freed from traffic, and the costal connection between Héricourt and the quartier des Quilles that will only be used for the beach access.
This action will have to be followed by a re-conquest of the top of the beach by an improvement of the protection of the dunes and beach, and a reorganization of the space of leisure between the sea and the triangle of Villeroy.
More in the West part, the National Road “RN 112” will be moved in order to release the spaces closer to the seashore, and thus make it possible to improve protection of the dunes and the beach against the aggressions of the sea and the human frequentation.”
Urban local documents
The urban plans of Sète and Marseillan concern this area.
The urban plan (Plan d’Ocuppation des Sols, POS) of Sète classifies nearly the entire LIDO as NC and ND zones, except for the Triangle of Villeroy, which is urban extension area (NA). NC zones don’t allow incompatible land uses with the agricultural vocation of the area. Only constructions related with agriculture are permitted. ND areas are even more restrictive without any kind of construction permitted (the camping of Castellas is in ND zone).
The urban plan of Marseillan (POS of Marseillan) classifies in zone NC and ND the grounds located East of the Grau du XVème , with restrictions virtually identical to those of the POS of Sète. The sector of Maldormir is classified as INA zone in the South of the railway, as NB sector North of the railway.
REGIONAL STRATEGY: Proposals on strategic orientations for erosion management in the Languedoc-Roussillon (Mission Littoral)
Mission Litoral is an administration entity dealing with coastal problems at regional scale. They look for long-term solution considering the interrelations between local zones and
regional phenomena and they have designed this regional strategy to orientate erosion management in an strategic level.
Under the chronic erosion problem that many sectors of the Languedoc-Roussillon region are suffering, the Mission Littoral has created this document in order to:
— Have an overview of the problem at regional scale — Define common principles to manage erosion
— Identify priority sectors and propose management strategies
This document identifies the coastal section from Sète to Marseillan as a priority considering the aggravation of erosion and the capital at risk.
It also recommends a backward movement of the coastal road as main strategy to face erosion problems (see figure 12)
Figure 5. Mission Litoral. Erosion management strategies. Source: Mission Littoral.
3.1.1.3 The land uses in the Lido of Sète
The lido of Sète is a site where many activities share a reduced piece of land. This area is already threatened by a coastal erosion problem and some human pressures over the environment that take place (urbanizations, waste disposal, and so on).
The lido has landscaping components which are located along it: the beach, road, dunes, vines, the railway, the squaring of salt mines and the dams (see Figure 6).
In this area, there are the old brackish marshes, in which the salt works of Castellas and Villeroy are located. The former is in the South-West part of the lido and it covers near 125 ha. The last is in the North-East part of the lido with a total surface of 200 ha. Both of them are separated from the lagoon by means of dams.
This part of the lido is classified as Zone d’Intérêt Ecologique, Floristique et Faunistique (ZNIEFF), where some rare and protected bird species nest and winter. But since the exploitation of the saltworks has stopped, this area has experienced some degradation due to the lack of maintenance of the installations resulting, for instance, in the damage of some dams.
At the beginning of the second half of the XVIIIth century the company of Salins de Cette, future Salins du Midi, obtained an important concession for the exploitation of the coastal zones. Then, the planning of the installation of the saltworks of Villeroy and the saltworks of la Quinzième to extract the salt has started.
In 1968, Salins du Midi ended the exploitation of the saltworks of the Lido. The facilities remained practically intact, at least in their great landscape structures (networks of channels and dams). The same year, the Town of Sète started to deposit its household refuse on the site of Large Rouchet, in the South of the Castle of Villeroy.
The lack of maintenance and managing of this site implied some consequences:
— The multiplication of wild deposits (rubble, scrap, wood), in particular on the Northern Saline sector of Villeroy, with the immediate contact of the urban zone; — The sweetening of the water layer, and
— The degradation of the dams delimiting the salt mines.
These dams take part in the protection of the vineyard. For this reason, the Domain de Listel and the Salins du Midi have reached to an agreement in order to insure the maintenance and the restoration of a part of the dams of Saline de Villeroy.
Figure 6. Linear components of the lido of Sète
Dunes system Salt mines of Castellas
Mediterranea Sea
Lagoon of Thau
Triangle de Villeroy
Coastal road
Railway track Domain de Listel
In the lagoon, the shellfish farming, established since 1880 in Sète, is the dominant activity. Annual production with around 13.000 tons oysters and 2.500 tons of moulds is the most important in the Mediterranean sea and represents 10% of the national production.
B. The middle part of the lido
Following the salt mines, there is a vast zone, on strongly salted ground, where it is possible to find some birds during the migration period in spring and in nesting period, as well as some rare vegetable species.
There are also two woodlands. One of them is the of Villeroy wood, which is a forest of two hectares, with interesting flora and fauna features, and the other one is the forest of Castellas, with less ecological interest than the former.
On the North-East sector of the lido the discharge of Villeroy can be found. The old discharge of Sète started to be used at the end of the 60’s, coinciding with the end of exploitation of the salt mines.
Between 1989 and 1990 the discharge of household refuse was forbidden, limiting the land use only for agricultural purposes. Nevertheless, rubble has continued being deposited there until 2000, the year of its effective closing.
A restoration programme, which is running since 2001, plans to finish at the end of 2006. The plan consists in creating hydraulic barriers to avoid possible contamination of external water (by the escape of lixiviates). It is also planned to cover the storage racks with a layer of impermeable clay to avoid the rainwater entering to the racks. There is also a study exploring the possible vocations of the old discharge compatible with legal, environmental and technical constrains (Littoral law, Water law, Sea Development Plan, LIKED, ZNIEFF, ZICO, Natura2000, containment of waste, and so on). This project has to be compatible with the project of sustainable protection and use of the sand strip between Sète and Marseillan, and in particular with stake of protection of the wet zones.
This part of the lido is called the triangle of Villeroy zone. It is a piece of land that has been re-qualified for urbanization purposes. The construction of housing, an urban park and a pedestrian path is planned. As a compensation measure, the Conservatoire du Littoral bought part of the old salt mines located behind the new urbanizations aiming at restoring them.
Next to the triangle of Villeroy the INRA department for vine conservation can be found. It was created by the INRA on the Domain de Vassal in 1949, and it is settled on 28 ha which are rented to the Domain de Listel. It currently shelters 7.500 vines, representing more than 2.200 types of vines of the whole world.
Nowadays they are running an important project of development and installations improvement, to some extent financed within the framework of the Contract of State-Region Plan.
The railway track and the road separate the INRA’s department from the Domain de Listel. This land is devoted mainly for vine growing, and it extends along the lido. The vineyards are one of the main activities in the lido (also in the region). It has been set up in the XVIth century and it covers near 60% of the lido surface (645 ha including vines, dunes, salt mines and wetlands).
In this area the Domain de Listel has 270 ha for cultivation (111 ha between the road and the railway which are almost all exploited for growing Sauvignon vine).
The 42 millions of bottles produced by the Listel each year (no matter the field origin) are bottled and stored in the installations near to the Castle of Villeroy. This provokes an important traffic of heavy lorries, estimated between 20 and 25 per day.
Direct sale are also done in the installations of the Domain de Listel. Approximately 20.000 bottles are sold each year, attracting an average of 7.000 visitors annually.
The vineyard is divided by the railroad track, and in its southern part the Camping of Castellas is located. This is the only camping in Sète. Moreover, it is the only tourist lodging in the lido. Its 1.000 sites (200 for mobile homes caravan and 800 for caravans and tents) are placed in its 24 hectares of territory.
The camping was created at the end of the 60’s. Located at 8 kilometres from Sète, in the northern side of the coastal road, its camping almost has direct access to the beach.
The installation to purify the water of Marseillan is located in the limit between Marseillan and Sète Communes. The municipality of Marseillan is projecting to construct a purifier of 75.000 m3 capacity, to ensure the treatment of the water which is influenced by the seasonal variation of the population (from the normal 7.000 inhabitants to near to 60.000 people in summer). For this purpose only twenty of the 157 ha that they have bought will be used. The rest of the land will be reassigned to the Conservatoire du Littoral becoming a protected zone.
3.1.2 Coastal erosion phenomena as a problem
3.1.2.1 Coastal erosion origin
Over the last 50 years, a number of human-made causes have changed the layout of this coastal area and led to a lack of sediment. The main one can be put down to the construction of the coastal road over the old dune system at the beginning of the twentieth century, which has decreased the capacity of the beaches to regenerate. Its effects are quite significant because the road reduces the protective effect of the dune system and increases the mobilisation of sediments, which is translated into an erosion of the backshore and the dunes. The coastal road blocks the morpho-dynamic processes of dune creation and restricts the sedimentary exchange between the dune and the beach. Furthermore, this situation has diminished the lifespan of the coastal road with the consequent economic costs of repairing it after storms (See Figure 7).
Figure 7. Storm in 1982. Source: Urbanis, 2003.
Other relevant causes can be pointed out as the interruption of the sediments provision by Rhone River because of its internal basin management. The presence of dams, the un-permeability of the ground due to urban expansion and other changes due to occupational patterns are responsible of the retention of sediments upstream, but prevent the new materials to become part of the coastal dynamic processes.
In addition, the construction of perpendicular barriers along the coast, as coastal defence structures in Lazaret beach and the Marseillan Port in the Lido affected directly the dynamics of the sediments, in particular the adjacent areas downdrift these structures.
Figure 8. View of the coastal defences in the Lazaret beach and the marina of “Quille’s” mouth.
3.1.2.2 What may be affected by erosion?
If the erosion of the Lido continues the beach will get narrower each year and we would assist to catastrophic economical, social and environmental consequences.
Basically four important activities would be affected by the erosion; Tourism, housing, vine cultures and fisheries. Moreover a unique and patrimonial ecosystem of marshes and dunes would disappear.
Erosion would affect the vine cultures. Indeed the sea would get closer to the vines, the level of salty water would get higher, and the vine roots would touch the salty water.
The railway itself would be threatened, if the water reached its dike.
If the lido gets narrower, the saltwater entrances would be more frequent, and this would be negative for the fishery activities. Indeed the oyster activity on the Thau lagoon leans on the quality of its semi-salty water, if this water happens to be more salty or colder, the quality of the production will decrease.
There is a camping situated on the south end of the Lido, just between the dunes and the road. It will be quite exposed to waves if the shore keeps getting nearer to the road. Indeed the road is actually more or less like a protective barrier for the camping, but it can also represent a danger in case of tempest, if the road is destructed.
Finally, in Marseillan Plage there is housing at risk, indeed 1982 the water came into the village flooding houses, and destroying walls.
All in all we can say that the erosion affects the whole ecosystem, the economy that lies on it, and of course it also affects the neighbour beaches and lagoons.
3.1.2.3 Awareness and action
The awareness and actions towards coastal erosion date from several decades ago. The first needs for protection appeared in 1953 on the north end of the camping Le Castellas (south-end of the lido), where the construction of three groins was needed to protect a 400m stretch of the coastal road and hence the camping facilities (see Figure 9). These groins contributed to maintain the shoreline position and the dune ridge.
Figure 9. Groin northwards of the camping Le Castellas.
After 1954 a groin was built in the Lazaret beach, which contributed to block an important mass of sediments and then, helped to increase the beach surface (more than 50m). But it has also affected negatively the beach southward.
Detached breakwaters have protected the touristic area of the lido, i.e. from La Corniche to the Villeroy triangle, in the period 1987-1993. In this sector the breakwaters assured a continuous maintenance of the sedimentary stock and of the present shoreline, tombolos were created behind these structures and the beach has gained more than 150m. However, the effectiveness of these coastal protection measures has been questioned because of their negative impacts downdrift of the last breakwater, showing a high erosive trend, especially intensive in the section where the coastal road is close to the beach. (See Figure 10)
The population became aware of the vulnerability of the Lido with the impact of several important storms, which caused diverse damages and high costs specially for repairing the coastal road. The following dates are the main storms:
— November 1982 storm, which destroyed the restaurants installed on the beach and public equipments. (figure 5)
— December 1992 storm, which involved the closure of the coastal road.
— December 2002 storm, the cost to repair its damages was estimated at 1 million francs.
Figure 11. Comparative situation between summer 2004 and winter storm in December 2004.
Currently costs of reparations from coastal storms represents approximately 250.000 euros for the municipality every year; most of them are dedicated to the coastal road.
Complementing all these hard protection schemes, different soft measures like wind-fences have been placed to maintain and consolidate the dune ridges. Until today, three generations of wind-fences have been performed between 1987 and 1990. As well as soft measures, some innovative techniques have been experienced, like wooden stakes planted on the beach berm (north of the three groins). These stakes, which reappear periodically, are intended to help the sediment transfer perpendicularly to the shoreline. Other measures were the permeably submerged structures placed in the mid part of the lido’s coast, which seemed not to produce accretion but at least to maintain the sedimentary stock of the beach; and a few sediment recharges in several sites of the municipalities of between Agde and Sète.
3.1.2.4 The solution: moving backward the coastal road
The history of interventions along the Lido coastline provides an illustration of the inefficiency of much of this coastal management and its increasing vulnerability.
As explained, the erosion is not affecting all sections of the beach in the same degree. The different protective structures as well as the orientation of the beaches and their location in reference to the perpendicular barriers (e.g. Marseillan Port) and the coastal road influence the degree of erosion. In general, the highest erosion rates are found in the extremes of the lido and a stable situation and a weak accretion in the middle section.
The narrow space, which separates the road from the shoreline, is not large enough to absorb breaking waves. Therefore, the coast is permanently fragile, it is translated into a sedimentary deficit, absence of dune ridge and a lowering of the beach profiles.
There is a historical discussion about giving sufficient space to the system in order to assure both the dynamic equilibrium of the beach, particularly in storm events, and an input of stabilisation of the sedimentary stock. The demand is based on removing the costal road and replacing it close to the railway, gaining enough space to restore the dune system.
In addition, lastly the cost of maintaining the coastal road and repairing storm damages seems incompatible with the maintenance of the beach surface. That is another reason why the move backward strategy has become stronger with the time.
Old people say that this idea dates back from the fifties. One fact that demonstrates this is that in 1971 the national government expropriated the land close to the railway for this purpose. Until today these lands haven’t been used yet.
Nowadays, the situation is still precarious in the Lido. That is why at the end of the ninetieths the municipality of Sète started a process to search for a long-term solution for coastal erosion in the Lido of Sète. In France this kind of interventions begins with a pre-operational phase, which is formed by 3 sub-phases: diagnosis, scenarios creation and project guidelines.
Based on legal documents as those described in the previous sections (See section 3.1.1.2.) and the regional strategy defined by the Mission Littoral, any proposal to face erosion in the Lido of Sète seemed to be under a move backward strategy. This type of policy implies removing infrastructures from the coastal zone and trying to recuperate the natural system as it was. It is commonly used for zones with high ecological interest where interventions should be more in accordance with its natural dynamics, or in those situations where strong erosion is difficult to control.
At the moment, the pre-operational phase is almost finished and the output documents are: 1. Diagnostic: BCEOM, 2000. This study has two parts:
— Diagnostic of the erosion causes and analysis of the evolution of the shoreline.
— Diagnostic of the terrestrial part analysing land uses and their relation with the coastal erosion.
2. Scenarios creation: BCEOM, 2001. This study is divided into: — Review existing techniques to face coastal erosion
— Scenarios creation to face the problem in the Lido of Sète
3. Project guidelines: URBANIS, 2004. This phase is formed by different documents that describe the chosen solution to be implemented.
In short terms, the proposal is based on a move backward strategy, which implies replacing the coastal road close to the railway. Naturalizing the area is another aim, through the restoration of the antique dune system giving a natural protection to the beach.
3.2 MULTI-CRITERIA STRUCTURE
With all the previous information it is possible to have a good understanding of the physical situation (coastal erosion), which has environmental and socio-economic implications. However, other conflicting aspects of the reality emerge from the worries of the local social actors. Those fears and expectations are gathered through social research (in-depth interviews and meetings) to be incorporated in the problem structuring. They are going to be used to construct the alternative solutions and the evaluation criteria.
Here, the stakeholders’ preferences (collected from the interviews, meetings and documents review) are presented. With this information it is possible to recognize how the problem has been defined, which allows a better understanding of how the possible scenarios can be constructed to solve the problem. Then, the current alternatives and the evaluation criteria (derived from the stakeholders’ preferences) are described.
3.2.1 Stakeholders preferences
Two major problems are seen in the Lido of Sète: the coastal erosion and the high frequentation rates, both of them bringing a wide range of impacts over several activities in the lido and its surroundings.
“A few years ago the sand burnt your feet while crossing the beach to reach the sea”. This opinion, given by a Sète’s citizen, reflects that the problem of erosion is present in people’s mind. This perception matches with the erosion rates described in Shoreline evolution and coastal erosion, Section 3.1.1.1.
It is a major problem, not only for the administration, who has been spending 250.000 €/year in repairing the coastal road, but also for the tourism sector. The depletion of the beach can be a difficulty for the development of this activity.
Besides the problem of erosion there is the frequentation issue. The parking along the road, the access to the dunes and to the natural spaces, and so on, reflects this trouble.
Social actors see the current situation from their own perspective, which is influenced by the impact over them. The visions of some social actors are presented in Table 4. These opinions have been collected by in-depth interviews and meetings carried out during September to December 2004 (see Table2 and Table3)
Table 2. In-depth interviews
Social actor Date
GRIVE (Groupe de Recherche et d'Information sur les Vertébrés et leur Environnement)
13th September
Ecologistes d’Euzière 13th September
Cooperative Marseillan 13th September
Syndicat Ostreicole Mytilicole du Bassin de Thau 13th September
Camping du Castellas 14th September
University of Perpignan 15th September
Tourism Office 13th October
Association of amateur fishermen 29th November
Sailing School of Barrou 29th November
Association of maritime hunt 29th November
SA.THO.AN (Société Coopérative Maritime des Pêcheurs de Sète-Môle) 30th November
ADENA (Association of Denfence of the Environement and Nature of Agde) 30th November
Association of defence of the inhabitants of Marseillan plage (DHMP) 1rst December
Table 3. Meetings.
Invited representative Date of the meeting GRIVE
Tourism Office
13th of October
Communauté d’Agglomération du Bassin de Thau Ecologistes d’Euzière
Domaine du Listel Mairie de Sète
Group/ Activity Observations Municipality of Sète
The municipality has been spending large am
ounts
of
money in repairing the coastal road after strong storm
s. They need and
want to stop this situation. They
also
see
the need of creating an integrated land uses
frame for the Lido of Sète, which facilitates the coexistence of
several activities. Co mmunauté d'Agglomération du Bassin de Thau
They have been looking for soft solutions (dune re
storation
) in
stead of h
ard on
es (breakwaters).
It has to be a long-term solution with a
cceptable and reasonable maintaining costs.
Recovering the dunes, stop the erosion and solving the problem
of over-frequentation are the
aims
of the Agglo. But they
have to
find the funds fo
r implementing
such a project, which is the main worry.
Mission
Littoral
This is an administration
entity dealing with coastal problems
at
a
regional scale. They look for long-term so
lutions considering
the interrelations between local
zones and regional phenomenon.
Tourism office
“It
is
important to combin
e tourism activities and environmental prot
ection” because the characteristics of the
lido are essential
for tourism development. Ano
ther prio
rity is co
ntro
lling the massive frequentatio
n and
diversify the tourism offer (“beaches for all tastes” and
“openi
ng
new spaces for soft activities (kite, cycling)
, like the zo
nes behind the railro
ad track”)
urism
Camping du Castellas
The current locati
on of the road doesn’t disturb them.
They are worry about their future situation (access
to the camping, possible
isolation and so on).
The think the camping caravans that park
along the road nowadays are an esthet
ical problem and not a financial one.
omic Domain e du L istel Th e activity of win e produ ction relies u pon th e lido’ s ch aracteristics an d u ses.
They see the camping caravans as a source
of pollution. Mainly because
of th
e lack of services to
enable the releasing of
to
urists’ wastes (
w
hich many times end in Listels’ lands)
.
It
is important for them to put special a
ttention in the security of the access to
the parking and to thei
r installations, due
to
the big amount of trucks going to the wine
cellars. Also for security reasons they are
against allo
wing peo
ple to
go
behind the
railroad track. The water management is a very important point for them. The wa
ter flows equilibrium has to be
controlled and maintained to
avoid an
excessive flow of salty wate
r go
ing up to
the vineyard lands.
Group/
Activity
Observations
Cooperative de Marseillan
The activities of wine production in
Marseillan won’t change with the plan of protection against eros
ion.
It is important to keep the cosatal road,
because it links Sète with Marseillan, wi
thout this link the number of tourists
in
Marseillan would decrease, and it woul
d be negative for their economy.
Also for security reasons it
is important to h av e t hi s r oa d, f or e xa m pl e i f t he re is a n a cc id en t i t l in ks t he h os pi ta l o f A gd e with
the hospital of Sète, and it is also useful in case of fire.
Syndicat Ostreicole
They don’t feel direct
ly concerned by the plan because their acti
vity proceeds on the Western part of the
“Etang de Thau”
It is important for them that the Lido
stands in position, if it disappears
they will have water quality problems.
Actually their major problem is the Oyster cultures at sea and
in the lagoon because of the in
crease of sea-breams who eat
their oysters. It is necessary to their point of view to
keep the road on the Lido, because “other
wise
all
the cars would use the road that
goes along the Lagoon, and there would be cons
equence on the water quality of the lagoon”.
Fishing sector, SA.THO.AN
The fishing se
ctor represents 1000 employees in Sète.
The fishing activity is directly concerned by the
erosion
of
th
e Lido, indeed if the Lido disappears the fisheries activity on
the
lagoon
will ch
an
ge.
It is essential to design a management plan of the erosion and
reorganise
the
Lido. Therefore it is essential to move the road,
prohibit cars to park along
the road, restore the dunes…etc
The plan will be positive mainly for tourism. One of the priorities is also to fi
nd a solution for the camping-cars.
As so ci at io n of am at eu r
fisherman and sailors
They knew about the plan, through the press.
They think this plan won’t help, to stop
the erosion. “If they put breakwaters,
the currents will change, the sa
nd will accumulate, the fish
will disappear and go away”.
The groins that were built are inefficient
so they think the brake-waters are not a g
ood solu
tion
eith
er.
They think nothing wi
ll
stop the erosion. The law says the camping cars, are forb
idden, but they tolerate the camping
cars on the road. It is a problem.
The fishing department prohibited anchorin
g for amateur fishermen in most of the zo
nes
of the lagoon, since it represents
concurrence to the professional fishermen. There
should
be
an
urgency way on the road, because it is obviou
s there will be accidents, it is better to have lots o small ca
r
parks and not two big ones.
Group/
Activity
Observations
Association of maritime hunt
They
agree
with
the moving of the road,
they
think
it
is
very interesting to be able to restore th
e dunes,
because it is a very
important ecosystem, which is linked to the Lagoon. They protect the ducks, because if
they disappear their hobby disappears
The brake waters are the best solution for th
e erosion, but it is too expensive. They pr
efer the dunes, they think it is good f
or
the visito
rs to
walk to
the beach thro
ugh a nice dune Landscape.
All the changes will have co
nsequences o
n the fauna.
They thin
k it is wonderful to try and
recreate what they used to see
when they were young for the future generations. They
have lo st three mo nth o f hunt ( M arch, February, and August
have been taken away)
, because it is the repro
ductio n period. Fren ch S ailin g S ch ool of Barrou
They are not sure something
can stop the er os io n, the ro ad o f co urse has to be mo ve
d to leave the nature restore itself and
form a u
ni
t...
They think it is a middle-term soluti
on, it improves the natural spaces.
They think a lot of
people
will
appreciate
to be on a quiet beach far from the road
. For their activity it will bring no change
s
because they do
n’t sail in fro
nt o
f the Li
do, they stay in front of the canal des
Quilles, and on the lagoon., The breakwaters
can be positive for the kitesurf acti
vity because they generate waves.
There
has
been
lot
of
retention of sand in front of the big dike
, they even have to take the sand away, every year otherwise
the entrance of the marina is blocked. The problem about brake waters is that they
are ugly and that there are lots of rats in
them. So it is also a sanitary problem.
cial
GRIVE
The problem is inserted in the whole
regional coastal dynamics. It has to be fa
ced
regionally
and
not only locally as it
is done today. “It is no t a pro blem o f co nstructio n, it is a pro blem o f frequentatio n”.
They see as a big problem the lack of management of the natu
ral zones behind the road. They think the access to these zones
has to be forbidden between April and July (to pr
otect birds during their reproduction period).
The frequentatio
n o
f the natural zo
nes behind the railro
ad track sho
uld be co
ntro
lled during the rest o
f the year.
Some lines of vineyards may be sacrificed in order to reco
ver the dune chains.
And the access to
the dunes has to
be
forbidden.
Group/
Activity
Observations
Ecologistes de l’Euzières
“The road is danger
ous and the noise of the road is disagreeable”.
The access to the central part of the be
ach has to be difficult for the people.
It is needed a long-term approach, to
avoid future damages and catastrophes.
The
breakwaters
are very anaesthetic. So, the best is to build as
less as possible and to put more
effort in recovering the dun
e chains. The n ew road sh ou ldn ’t promote
the access to natural spaces.
A.D.E.N.A.
The erosion problem has to be so
lved,
the
road has to be moved, and the d
unes and beach have to be protected, becaus
e
they have a very important ecological value. It is important to organise all type of in
fo rmatio n fo r the inhabitants, and to urists.
It is a good idea to eventually guide
the people through the natural spaces.
Association of defence of the inhabitants o f Marseillan plage
The dune regeneration is the best solution, the inhabitants of Ma
rseillan plage are really threatened by this erosion problem.
The
road
has
to
pass outside Marseillan, (in the North option) fo
r security reasons for the inhabitants of Marseillan Plage, an
d
to improve the access to Marseillan village. It is important to stop the erosion, but also to link th
e Plan of Management with Marseillan, and think globally
Most of the interviewed people agree with the need of concentrating the parking zones, avoiding the permanence of cars along the road. Moreover, most of them prefer limiting the parking capacity to the actual level of visitors.
Both “GRIVE” and the “Ecologistes de l’Euzières” see the need of a monitoring scheme to follow the evolution of the system.
3.2.2 Alternatives
The main objective of the alternatives is to define a strategy to protect the Lido from the coastal erosion. The alternatives defined are configured and based on different sources:
• Scenarios defined by BCEOM (2001) • Solution proposed by URBANIS (2004)
• Interviews and focus groups with local stakeholders • Experts’ opinions
The displacement of the road is the element arisen in the previous sections as a key component to define different philosophies of action. On this basis, four main lines have been established:
• Do nothing and maintaining the current situation (BUSINESS as USUAL)
• Coastal defences on the shoreline and reduced intervention on the Lido (HARD-ENGINEERING).
• Move the road backward until the limit west of the ancient dunes. (MEDIUM-DISPLACEMENT OF THE ROAD)
• Move the road backward just close to the railway (ROAD DISPLACEMENT) As the beach erosion is not the only problem identified in the Lido, some alternatives try to include solutions to the “Camping cars invasion” and dune system degradation. That is why each line has different variations depending on the added elements (parking, cycling track, access to the beach). At the end, many alternatives are more an integral land use plan than only a coastal defence strategy.
However, only the eastern area of the railway has been taken into account to create the alternatives. This is the part directly affected by erosion. Some stakeholders have highlighted the western part of the Lido in terms of nature conservation because of its high biodiversity value.
The alternative of massive nourishment of the lido was considered at the first stages but refused following the experts’ advices, who opined that there are no sand reservoirs in the surroundings.
In total 9 alternatives are described in order to do the multi-criteria evaluation.
A. BUSINESS as USUAL (BaU)
This alternative implies remaining in the current situation. Coastal erosion is only faced with high monetary-cost, emergency procedures like repairing the road when it is damaged by a storm, maintaining the breakwaters in front of the Lazaret beaches and
cleaning the road and the dunes periodically. The parking is allowed along the road and the camping cars often occupy most of the sea side.
B. HARD-ENGINEERING
The coastal road is maintained in the current place so the alternative of hard-engineering options has to be developed in order to fix the beach.
This alternative is mainly based on the construction of detached breakwaters along the entire lido. This option permits to maintain the coast, but with complementary nourishments to create the tombolos and some nourishments are also expected in order to avoid the digging of the costal line between successive breakwaters.
The breakwaters arise +1m. above the sea level, so they hide the horizon line for the beach users
B.1. PARKING ALONG THE ROAD
The road is maintained but with a displacement of the central axis inland, which will permit a unilateral parking in the seaside. In the north area of the road the ancient dune system will be restored.
B.2. PARKING AREAS
Concentration of the parking areas in two points with a dispersion of the users along the beach through the public transports, which will help to increase the security of the road and reduce the expansion of the camping cars. The capacity of reception is about 750 vehicles in each area.
C. MEDIUM DISPLACEMENT OF THE ROAD
The coastal road is displaced until the west limit of the ancient dunes, on the less productive agricultural lands.
This option permits to reconfigure the shoreline and the beaches with few engineering measures only in front of the Villeroy triangle. A cycling track is going to be installed parallel to the road on the seashore.
This set of alternatives implies remodelling the camping located on the Lido as part of the whole project.
C.1. PARKING AREAS
It is planned to park in delimitated parking areas of around 500-600 places each. They will be located between the new road and the railway. From each parking area a delimitated access to the beach will be provided, in order to avoid people crossing through the dune system.
C.2. PARKING ALONG THE ROAD
The parking is organised along the road in a parallel band of 8m separated physically from the road by a wall. Several accesses to the beach are going to be implemented with more frequency (each 100m) than the C-1 option, to avoid users crossing through the dune system and damaging it.
D. BACKWARD MOVEMENT
The route is displaced close to the railway profiting the land acquisition performed by the State twenty years ago (44 ha continues from Sète municipality and 4,7 ha discontinues from Marseillan municipality). This option permits re-establishing the shoreline with few engineering measures, only in front of the triangle of Villeroy.
This set of alternative also implies remodelling of the camping located on the Lido as part of the whole project.
D.1. PARKING AREAS
It is planned to park in delimitated parking areas of around 500-600 places each. They will be located between the new road and the beach. From each parking area a delimitated access to the beach will be provided, in order to avoid people crossing through the dune system.
D.1.1. Cycling track in the west limit of the ancient dunes
The cycling track will be located in the west limit of the ancient dunes separated from the parking areas and the coastal road.
D.1.2. Cycling track parallel to the road
The cycling track will run parallel and close to the road. A natural separation in order to improve landscape quality will be designed.
D.2. PARKING ALONG THE ROAD
The parking is organised along the road in a parallel band of 8m separated physically from the road by a wall. Several accesses to the beach will be implemented with more frequency (each 100m) than the D-1 option, otherwise users can cross through the dune system and damage it.
D.2.1. Cycling track in the west limit of the ancient dunes
The cycling track will be located in the west limit of the ancient dunes separated from the parking areas and the coastal road.
D.2.2. Cycling track parallel to the road
The cycling track will run parallel and close to the road. A natural separation in order to improve landscape quality will be designed.
