Faced with the continuous retreat of the coastline and the gradual disappearance of several beaches of the cornice, the project to protect the coast of Bizerte combines sand reloading and rock works. Based on hydrodynamic, sedimentary, environmental and social studies, it aims to sustainably restore beaches while limiting the effects of the work on the marine environment and coastal uses.
For several decades, the coastline of the Biserte Corniche has undergone progressive erosion under the combined effect of natural and human factors. The force of the waves, the sea currents, the displacement of sediments and the evolution of coastal uses have led to a marked retreat of the coastline.
Over nearly five kilometers, the beaches almost completely disappeared. The Sidi Salem area, which extends for about two kilometers, still retains a relatively large stock of sand. Nevertheless, it remains exposed to continued erosion in the absence of adequate protective measures.
It is in this context that the Coastal Protection and Planning Agency has embarked on the Bizerte coastal protection project, as part of the Tunisian Coastal Protection Program. Co-financed by the German Development Bank KfW and Invest International, the project aims to slow down the retreat of the coastline, restore the balance between water and sediment movements as much as possible and promote the reconstitution of the most affected beaches.
A solution chosen after comparing several scenarios
The technical choice results from a thorough comparison of several scenarios. Numericatic models were used to analyze waves, currents, sand transport and the probable evolution of the coastline in the long term.
The simple reloading of the beaches by the contribution of sand, without a protective structure, was among the solutions envisaged. However, studies have shown that it would not guarantee lasting protection: under the effect of waves and currents, sand would be gradually redistributed, which would require the operation to be renewed every three years or so, with high and recurring costs.
The installation of submerged blade breakers has also been studied, but their effectiveness has been considered limited in the context of Bizerte, where the waves usually arrive obliquely. These works are more efficient when the swell reaches the beach almost perpendicularly.
Another scenario provided for the construction of a large number of short rocky ears, which could reach about twenty works along the coast. Although technically possible, this option would have greatly modified the coastal landscape, reduced the space available for seaside activities and raised difficulties of social acceptability.
The solution finally chosen combines the reloading of sandy beaches and the construction of a limited number of rocky Exes, longer and more spaced out. The objective is to stabilize sandy contributions and organize their displacement, while reducing the grip of the works and their effect on the landscape and coastal uses.
A project adapted to new constraints
The initial project envisaged the construction of three rocky ears. However, its configuration was adapted before and during the execution of the work, following technical and financial constraints that appeared after the first studies.
The main change is related to the installation, in 2024, of an underwater telecommunications cable in the area initially reserved for the first spike. In order to preserve both this infrastructure and the coastal protection project, the first work was moved. The shape of the second ear was reviewed and a small complementary work, called « épi 1 bis », was added.
The realization of the third spike was postponed due to the limits of available funding, while maintaining the possibility of building it later if additional resources are mobilized. To strengthen the protection of the sector concerned, the extension of about 260 meters of the longitudinal structure in rocks was retained.
Each change was the subject of a complementary study, conducted according to terms of reference validated by the funders. The revised device has been subjected to new hydrodynamic and sedimentary models as well as analyses of the evolution of the coastline. The results indicate that the adapted configuration remains able to promote the reconstitution of the beaches, preserve the volumes of sand and reorganize the sedimentary exchanges in the area concerned.
Physical tests to verify the stability of the structures
Tests are carried out at the ArtLab Laboratory in Artelia to verify the stability of rock structures and their ability to resist waves and marine conditions retained during design.
These tests do not correspond to a new design of the project or to the correction of previous errors. They constitute a verification step provided for as soon as the tender file is prepared and integrated into the works contract.
The laboratory evaluates the hydraulic behavior and stability of the structures under the effect of the dimensioning waves. Sand dynamics, beach stability and long-term coastal balance were, for their part, studied using numerical models and sediment analysis conducted during the design phase. The first available results show a behavior in accordance with the technical objectives under the conditions studied.
Particular attention paid to the marine environment
Water quality, seabed and posidonia grasslands are among the main environmental concerns of the project. Two complementary environmental and social studies were carried out: one concerns the marine area selected for sand extraction, the other the reloading areas and the coastal areas directly affected by the work.
A specific study was also devoted to posidonia herbariums, an essential habitat for the ecological balance of the Mediterranean. The potential effects of sand extraction, transport and discharge were analysed, and prevention, reduction, monitoring and, if necessary, compensation measures were defined.
The sand intended for reloading was subjected to physical and chemical analysis from samples taken at different depths. The results indicate that the materials meet the required characteristics and that no source of contamination has been identified. Extraction must also be carried out in areas without posidonia herbariums, with marine biodiversity monitoring to reduce the affected areas and the duration of interventions.
During the work, a device measures the turbidity of the water. Marks are placed at the boundaries of the herbariums to monitor the spread of suspended matter. When the observed levels are likely to threaten sensitive areas, the procedures provide for the temporary interruption of the operations concerned.
A summer suspension and a secure construction site
During the summer season, work is temporarily suspended in order to preserve beach use and reduce risks for summer visitors. The construction site nevertheless remains secure and its access remains prohibited, especially near unfinished works.
Site monitoring is provided to prevent accidents. Residents and users can contact the head of the control mission or the project communication manager for information, send their observations or file a complaint.
Consultation at the heart of the project
Public participation began with the preparation of studies and comparison of protection scenarios. A first public meeting, organized on July 20, 2020, a
allowed to present the different options and to discuss the proposed solution. Another meeting, held on January 13, 2022, focused on the detailed project and the scenario chosen. A public consultation was also held in Bizerte on April 10, 2025 as part of the environmental and social assessment.
These meetings brought together representatives of public institutions, regional and municipal authorities, fishermen, tourist establishments, environmental associations, beach operators and other stakeholders. They made it possible to explain the results of the studies and the technical hypotheses, but also to collect the observations and proposals of the participants in order to integrate them, when possible, into the final design and the environmental and social management plan.
Consultation continued during the execution of the work. Meeting within a local monitoring committee, representatives of civil society and local residents participate in periodic meetings and site visits. They exchange with those responsible for the project, relay the concerns of users and are informed of technical adjustments, the traffic plan and the security measures put in place during the seasonal stop. Together with the municipality, they will also be associated with the development of future beach occupation and management plans for the exploitation phase.
Essential follow-up after the completion of the work
The responsibility of the project will not end with the construction of the works and the reloading of the beaches. A permanent monitoring program should make it possible to observe the evolution of the coastline, the volumes of sand, the stability of the beaches and the behavior of the works.
This system will be based on regular inspections, topographic surveys and marine measurements. Future maintenance operations will be determined on the basis of the results observed in the field. A first overall evaluation of the operation of the system could be conducted after an estimated period of about ten years.
An agreement will also have to be concluded between the Coastal Protection and Development Agency and the Municipality of Bizerte to specify the responsibilities of each party in terms of monitoring and maintenance. The municipality and other actors concerned will be accompanied in the preparation of a beach occupancy and management plan, intended to organize tourist and commercial activities while preserving the restored works and spaces.
A long-term investment for Bizerte
The combination of rock structures and sand reloads is used in many countries to protect erosion-sung coasts. Comparable solutions have been implemented in Italy, Spain, Portugal, France, the Netherlands and the United States.
The goal is not to transform the coastline into an artificial space, but to intervene when erosion exceeds the natural regeneration capabilities of the environment and begins to threaten beaches, infrastructure, urban areas and economic activities.
The Bizerte coastal protection project is thus a long-term investment to protect the city and the property of its inhabitants, restore its beaches and strengthen its environmental and tourist attractiveness. Its success will depend on the quality of the execution of the work, the continuity of scientific monitoring and maintenance, but also on the transparency of information and the maintenance of a permanent dialogue between public institutions, the municipality, civil society, residents and the various users of the coast.
