The mouth of the Oka estuary was once home to coastal dune systems that disappeared in the 1990s due to both anthropogenic factors (such as sand extraction and trampling of vegetation) and natural processes (including erosion caused by marine storms, waves, currents, and wind). As a result, Laida Beach in the Urdaibai Biosphere Reserve has lost nearly 50% of its original extent.
The absence of dune systems has led to morphodynamic instability and, consequently, a decline in the diversity of habitats and species in this estuarine area. Likewise, increased vulnerability of existing infrastructure, the complete destruction of dunes and vegetation, and unregulated visitor intrusion have made natural regeneration impossible.
In the context of climate change, restoring the Laida dune front is essential as an adaptation measure to maintain beach stability, protect existing infrastructure, and ensure that recreational use remains compatible with the ecological goals of restoration.
The mouth of the Oka River, which forms its estuary, is the area where estuarine sedimentary dynamics are most active due to the combined action of waves, tidal currents, and wind. The balance between these forces is maintained by the continuous movement of sand among the estuary’s various components, and this constant variability gives rise to ongoing processes of erosion, transport, and sedimentation across different areas.
However, the Urdaibai Estuary is the largest (1,015 ha) and best-preserved estuary on the Basque coast. It includes the dune area of Laida Beach, which is part of both the SCI “Coastal Areas and Marshes of Urdaibai” (ES2130007) and the SPA “Ría de Urdaibai” (ES0000144).
In general, natural dune ecosystems along the Basque coast are extremely scarce, degraded, and undergoing regression. Under these conditions, the regeneration of the Laida dunes—covering an area of approximately 6 hectares—represents a major contribution to the recovery of the entire estuarine ecosystem.
In this context, the project to regenerate the Laida Beach dune system was first conceived in the late 1990s in response to the critical state of the area, which had suffered more than 50 years of progressive loss and degradation. During this period, the dunes ceased to fulfil their protective role and their function in coastal configuration and the conservation of natural heritage. The fundamental objective of the project was to restore Laida Beach, within the Urdaibai Biosphere Reserve, by regenerating its coastal dunes, recovering their full ecological functionality, and responding to a strong social demand for restoration.
Regeneration began in 1999 with a pilot experiment conducted in the northwestern part of the beach to determine the environmental characteristics of the site, observe sand capture and accumulation dynamics, and quantify the volume of sand deposited in the accumulation zone. The results confirmed the beach’s capacity to once again host a large dune system capable of stabilizing and consolidating Laida Beach. Consequently, a comprehensive dune regeneration project was developed to consolidate the beach as a whole. This project was subsequently implemented in 2001, 2002, and 2003, involving the installation of sand traps and the planting of dune vegetation.
The results, supported by a rigorous scientific study, encouraged the extension of the intervention to a much larger area, carried out with the collaboration of LIFE-Nature through the project “Integral Regeneration of the Dune System of Laida Beach” (LIFE04NAT/ES/000031), granted for the period 2004–2007 to the Board of Trustees of the Urdaibai Biosphere Reserve as the project’s beneficiary.
One of the main threats to the limited existing or potentially recoverable dune habitats was visitor intrusion, although other natural and anthropogenic factors that hinder the development of mature dune ecosystems were also influential.
This intrusion, combined with wind action (in the absence of obstacles to trap transported sand), extreme storm events (causing large-scale sand displacement), tidal and wave influence, and the improper relocation of dredged materials from channel maintenance, prevents the structured development of dune areas. This results in the loss of developing sand accumulations and reduces the dunes’ capacity to store sand, ultimately disrupting the hydrodynamic balance of the estuary.
Furthermore, the presence of a major shipbuilding company within the estuary requires periodic dredging of the entrance channel, involving sand disposal operations that have sometimes resulted in the filling of marsh areas. In any case, the volume of sand extracted should be kept to an absolute minimum and should respond exclusively to the real depth requirements at that time, since there is no such thing as “definitive dredging.” The greater the volume of sediment removed and discharged, the more severe the estuarine system’s subsequent response will be, due to its high natural dynamism.
Nevertheless, the series of intense storms in 2014 eroded much of the intervened area and the works previously carried out, but they also provided valuable lessons on how to approach climate adaptation in such environments. These insights informed the design of new actions aimed at the proper restoration, recovery, and consolidation of the affected areas.
The project forms part of the restoration of coastal dune systems along the European Atlantic coast, as defined in the EU Habitats Directive, and focuses on the conservation of embryonic shifting dunes, mobile white coastal dunes, and fixed grey coastal dunes with established herbaceous vegetation.
Its overall objectives were twofold:
To regenerate the coastal dune ecosystems at the mouth of the estuary by using dredged sands from the estuary and applying bioengineering techniques for restoration.
To raise awareness of the ecological value of dune ecosystems.
These general objectives were translated into specific actions aimed at:
- Regenerating the coastal habitats of Laida Beach by consolidating the fixed coastal dunes with herbaceous vegetation (grey dunes) already established in previous years, and by creating new mobile dunes with characteristic dune species such as Ammophila arenaria (marram grass) and Elymus farctus, among others (white dunes).
- Promoting the formation of new mobile dunes through the early colonization of embryonic vegetation.
- Regulating the recreational use and management of the beach to prevent habitat degradation and stop visitor intrusion, which damages the dunes by trampling, destroying their morphology, formation processes, and natural plant colonization, thereby preventing natural regeneration.
- Raising awareness among beach users about the importance of dune ecosystems as natural assets that must be preserved and respected.
- Using dredged sands as a sediment source for wind-driven processes that help restore previously existing dune ecosystems.
- Serving as a model for future interventions in similar coastal environments
In general, the actions undertaken in the past were not implemented in the most environmentally appropriate way. Therefore, with the current project — and its objectives and specific actions designed to address the identified challenges — the approach now focuses on:
• Taking advantage of potential synergies among the stakeholders involved.
• Facilitating the natural formation of dune environments in areas where they historically existed.
In this way, natural resources and habitats will be gained rather than lost in the future, contributing to coastal protection and shoreline defense as an adaptation measure to climate change.
However, the severe storms that occurred in 2014 required the reconsideration of certain planned actions in the area, in addition to replacing the damaged infrastructure.
The measures implemented during the development of the project were based on previous restoration actions carried out in earlier years, which were further completed and consolidated.
In this regard, the different types of actions undertaken during the project implementation period consisted of the following:
Management tasks on Laida Beach:
Installation of sand collectors: achieved by manually placing wicker stakes in parallel lines across a total surface area of approximately 60,000 m², as well as replacing deteriorated elements previously installed.
Perimeter fencing for dune protection: installation of ropes attached to treated wooden posts to prevent human intrusion and safeguard the regeneration process, accompanied by regular maintenance.
Planting of dune vegetation: introduction of seedlings in newly formed dunes, where sands from dredging were deposited, and replacement of seedlings in previously restored and regenerating areas. For this purpose, stabilizing species such as Ammophila arenaria, Elymus farctus, and Elymus athericus were used to promote the natural recovery of the dunes’ sedimentary and biological cycles. The planting density was approximately 10 units per square meter, with an estimated total of around 875,000 specimens, sourced both from the Loredo nurseries (Cantabria) and wild specimens collected from a nearby sandy area in Sukarrieta, without affecting the existing plant community.
Maintenance and cleaning of the area: establishment of a waste collection service to remove debris transported by the wind, along with visitor information and awareness activities, and inspection of installed equipment, particularly during the summer season.
Public awareness and dissemination of results: aimed at visitors to Laida Beach, the Urdaibai Estuary, and the general population of the Basque Country, through the installation of information panels to raise awareness of the ecological value of the dunes and their importance for the ecosystem and coastal protection, thereby fostering respect and appreciation for these natural environments.
In addition, directional and interpretive signage was installed, media appearances and advertisements were carried out, and informative leaflets were distributed at the headquarters of the Board of Trustees of the Urdaibai Biosphere Reserve and in local tourist offices.Project management and operational control: undertaken by a Technical Coordination Secretariat, responsible for overseeing project implementation and ensuring its administrative and financial management.
Biological and geological monitoring: focused on tracking the outcomes of restoration and adaptive management actions, based on the generation and application of scientific knowledge.
The coastal areas of the Basque Country are highly exposed and vulnerable to the risks associated with climate change, which will inevitably affect the lives of local populations, economic activities, and the natural environment, particularly in estuarine zones.
On the Basque coast, sea level is rising at an average rate of around 2 mm per year, a trend that, if sustained over time, could lead to significant alterations in the habitats of the Urdaibai Biosphere Reserve.
In this context, Laida Beach is considered one of the most vulnerable sandy areas to the impacts of climate change, as it is located in the outer section of the estuary, where the intensity and frequency of marine storms, as well as the extent of tidal action, are likely to increase in the future.
Therefore, in the current scenario of climate change and sea-level rise, the regeneration of the Laida Beach dune front is essential as an adaptation measure—to maintain coastal stability, protect existing infrastructure, and ensure that recreational use remains compatible with the ecological objectives of the restoration.
The Board of Trustees of the Urdaibai Biosphere Reserve was the entity responsible for proposing, preparing, and executing the project for the regeneration of the Laida Beach dune field, with the collaboration and financial support of the Department of Environment and Territorial Planning of the Basque Government and the European Union.
For the implementation of the project, staff from the Urdaibai Service were responsible for its coordination and management, while specialized external contractors were engaged through public procurement to carry out the various works and tasks involved—excavation, planting, reforestation, perimeter fencing, maintenance, topographic surveying, and photographic documentation, among others.
One of these companies acted as Technical Secretariat, selected for its experience in similar restoration projects.
In addition, a specialized external audit service was commissioned to ensure the final verification and monitoring of the project.
Furthermore, during the implementation period, several technical studies and reports were commissioned and completed, including the following
- Sedimentological monitoring and evaluation of the Laida dune regeneration project, carried out by the Department of Stratigraphy and Palaeontology of the University of the Basque Country (UPV) in collaboration with the Technical Service staff of the Board of Trustees of the Urdaibai Biosphere Reserve.
- Monitoring of biological colonization of the Laida dunes, conducted by the Department of Plant Biology and Ecology of the University of the Basque Country (UPV), with the aim of assessing the development of planted vegetation and its progressive natural colonization by native flora and fauna.
- Morphodynamic monitoring at the mouth of the Oka estuary, undertaken jointly by the Department of Stratigraphy and Palaeontology of the University of the Basque Country (UPV) and AZTI-Tecnalia.
In addition, several scientific publications were produced (see bibliography).
The main beneficiaries of the project, both in terms of its objectives and the enjoyment of the restored environment, were the municipalities located around the estuary—Ibarrangelu, Elantxobe, Gautegiz-Arteaga, Kortezubi, Bermeo, Gernika-Lumo, Mundaka, Sukarrieta, Busturia, Murueta, Forua, Muxika, and Arrazua—as well as the general visiting public.
To this end, several public information and awareness campaigns were carried out, involving the distribution of materials such as leaflets, comics, puzzles, and other educational items, along with communications promoting the importance of dune conservation, respect for the natural environment, and dissemination of the project’s results.
An exhibition was installed on Laida Beach and in nearby towns, and basic visitor guidelines were shared to encourage responsible behaviour when visiting the restored area.
In addition to these activities, other complementary initiatives were undertaken, including the production of an audiovisual documentary in DVD format, targeted environmental education campaigns for schools, and enhanced visitor engagement during the summer season, with the following notable actions:
- Guided itineraries and teaching materials for schoolchildren
- Guided tours and information material for visitors
- Training-informative visits to educational centres
- exhibitions
Information and results were also disseminated through the www.euskadi.net/urdaibai and www.urdaibai.org websites, with the following general scheme:
- Introduction: overview of the issues affecting dune ecosystems on the Basque coast and the objectives of the project.
- Project: description of the Laida dune system and the actions implemented since the start of the project.
- Scientific monitoring: compilation of scientific reports documenting the evolution of the dune system.
- Environmental education: materials developed throughout the project, including information panels, leaflets, exhibitions, comics, educational games, and teaching resources.
- Photo gallery: photographic record illustrating the evolution of Laida Beach.
- Video: audiovisual documentary produced during the course of the project.
Due to the rocky and cliffed nature of the Basque coast, sandy dunes represent one of the rarest coastal ecosystems along the shoreline. After their systematic destruction and degradation over the past two centuries, and given their importance as a natural coastal protection system and their role in conserving natural heritage, the maintenance and regeneration of these unique ecosystems has become a matter of great social and environmental interest.
The dune regeneration experience produced very positive results in all respects. Moreover, thanks to the continuous monitoring of sedimentary, meteorological, and oceanographic processes carried out during the implementation of the project—and currently maintained by the Urdaibai Reserve Service, in collaboration with other Basque institutions such as the University of the Basque Country and AZTI—precise data are now available on the prevailing wind patterns at Laida Beach, the sedimentary characteristics of its dune system, and the sedimentary dynamics of the Oka estuary.
This information constitutes an essential tool for establishing management criteria that support sound decision-making in the management of this protected area and in the development of initiatives aimed at preserving estuarine ecosystems and their natural heritage.
Within the restoration area, however, intense erosion has been detected in certain zones, alongside sediment accumulation in the northern intertidal area. In recent years, there has also been an increase in the intensity and frequency of storms, which continue to erode the coastline and cause beach retreat.
Furthermore, dredging operations within the estuary have been found to significantly influence sedimentary dynamics, altering the natural coastal and estuarine processes involved.
In any case, the dune regeneration project at Laida successfully consolidated an ecosystem of exceptional ecological importance, laying the foundations for progressive environmental recovery in the coming years. Both during its execution and subsequent monitoring, the project has generated valuable information on the functioning of dune ecosystems and the coastal and estuarine dynamics that sustain them.
The 2014 storms, which caused severe erosion of all restored supratidal areas, led to the transport of sand into the inner estuary, a process that will likely continue gradually, further driven by the expected sea-level rise of approximately 2 mm per year.
For these reasons, the recovery and consolidation of the Laida dune system are of both environmental and socio-economic importance—expanding the surface area of this habitat of community interest, enhancing biodiversity, stabilizing supralittoral terrain in the estuarine zone, reducing erosion, and promoting sustainable public use and environmental enjoyment.
These actions also strengthen connections between local municipalities and coastal communities and improve overall environmental quality, with a positive impact on the sustainability of tourism and regional development.
The implementation of the project produced positive results across all key milestones.
Dune accumulation and configuration:
Sand accumulation within the regeneration area was substantial, occurring continuously throughout the monitoring period and resulting in the recovery of approximately 9.5 hectares of dune field.
During the morphological development of the dunes, two distinct phases were identified: an initial vertical accretion phase followed by a horizontal expansion phase.
It is essential to maintain continuous monitoring of sedimentary, meteorological, and oceanographic processes, as this constitutes a critical tool for informed decision-making in the prevention and management of dune dynamics.
The use of dredged sands made it possible to restore and prepare large affected areas as a foundation for dune regeneration, although dredging operations continue to significantly influence sedimentary dynamics in the area, altering natural processes.
Colonization and plant fixation:
The dune vegetation community plays a key role in stabilizing sand and building dune structure, thereby reducing erosion and preventing displacement.
Perimeter fencing effectively protects the intervention areas from human disturbance, and has proven essential to the success of the planting efforts.
It is necessary to maintain optimal conditions to promote the rapid development and biological colonization of the dunes.
Biological regeneration produced excellent results, progressing rapidly—from six plant taxa recorded in 2001 to 28 characteristic dune species by the end of the project.
The first embryonic dunes appeared spontaneously and naturally, initially colonized by pioneer species such as Cakile maritima (sea rocket), Salsola kali (saltwort), and Polygonum maritimum (sea knotgrass).
Ammophila arenaria (marram grass) and Elymus farctus (sand couch) were planted as key fixation species.
Subsequently, other typical dune species appeared naturally, including Honkenya peploides (sea sandwort), Eryngium maritimum (sea holly), and Euphorbia paralias (sea spurge), among others.
In addition, certain dune-associated insect species, such as the bee wolf (Philanthus triangulum), began colonizing specific areas, indicating a favorable recovery of habitat complexity.
It was found that the disposal of dredged sand effectively reinforced dune stability against potential marine flooding, functioning as both a sediment and seed trap. This process enhanced biological colonization within the dunes and created optimal conditions for their rapid development.
Public use of the restored area:
A substantial expansion of Laida Beach was achieved—up to 18.5 hectares at low tide—which significantly increased the area available for public use.
The installation of protective fencing around the regenerated area proved highly effective in its consolidation, especially when combined with targeted information and communication campaigns.
The restored area was generally well respected by visitors, with only isolated cases of disturbance recorded.
The implementation of public information and awareness campaigns produced very positive results, ensuring respect for facilities, plantings, and environmental cleanliness, despite annual visitor numbers exceeding half a million.
Although the project successfully achieved all its objectives, several factors affected its implementation to some extent, including:
The initial shortage of available seedlings, which required that planting be carried out gradually throughout the project period rather than exclusively at the start. However, this approach offered certain advantages, such as reducing the number of wicker structures that needed to be installed or replaced.
The initial continuous placement of sand-collector lines, which hindered the subsequent formation of dunes in later rows. Greater efficiency was observed when the collectors were installed progressively, followed by planting activities.
Lower planting requirements than originally planned, due to favorable natural colonization conditions.
Changes in the surface configuration of the dune area, resulting from the redistribution of artificially added sand by marine and estuarine currents, which caused recession on the inner side and expansion toward the sea. This made it necessary to relocate parts of the perimeter fencing and modify the shape of the dune ridge.
The artificial replanting of already consolidated dunes, which distorted the monitoring results regarding their natural development and recolonization processes; therefore, it was decided not to intervene further in these areas.
The same decision was taken for previously planted areas that had become bare of vegetation due to natural causes, opting not to replant them.
Once the project was completed, severe marine storms in 2014–2015 again eroded the restored dune system, removing much of the rehabilitated area and the work previously undertaken, and causing the disappearance of the entire supratidal zone as well as damage to infrastructure (such as access paths, retaining walls, and drainage channels).
However, these events provided valuable lessons and served as a basis for designing subsequent replacement and regeneration actions implemented in later phases.
The total cost of the project amounted to €522,568.00, an amount that was financed at 50% (€261,284.00) by the Department of Environment and Territorial Planning of the Basque Government and the European Union, through the approval of the Life programme "Integral regeneration of the dune system of Laida beach" (LIFE04NAT/en/000031), granted as a beneficiary to the Board of Trustees of the Urdaibai Biosphere Reserve in 2004.
This final amount corresponded to the following application table:
- External company jobs............................... 441,257.00 €
- inventoriable material................................ 19,958.00 €
- travel and subsistence allowances............. 26,843.00 €
- Consumables.............................................. 25,230.00 €
- Other costs................................................. 9,280.00 €
As additional benefits, the Laida dune regeneration project has expanded the area of public use of the beach, especially during high tides, and has consolidated an ecosystem of special ecological importance, laying the foundations for a progressive biological recovery in the coming years.
Biological regeneration has given excellent results, producing a very rapid plant regeneration, with a great explosion of colonizing biodiversity, exponentially increasing the number of taxa and their uniqueness in the area.
The project developed is, among other provisions, framed by the following legislative framework:
- Law 5/1989, of 6 July, on the Protection and Management of the Urdaibai Biosphere Reserve, which establishes a special legal regime for the Urdaibai Biosphere Reserve, in order to protect the integrity and promote the recovery of its gea, flora, fauna, landscape, waters and atmosphere and, in short, of all its ecosystems due to their natural, scientific, educational, cultural, recreational and socio-economic interest
- the Programme for the Harmonisation and Development of Socio-Economic Activities (PADAS) approved in 1998 (Local Agenda 21 of Urdaibai), an instrument for the development of the P.R.U.G., approved by the Basque Government through Decree 258/1998 (B.O.P.V. nº 200, of 21 October 1998), whose main objective is to promote, guide and coordinate the different activities of the production sectors involved in the non-developable land of the Urdaibai Biosphere Reserve, in coordination with the plans and programs of urban enclaves
- Decree 27/2003, of 11 February, amending the Master Plan for the Use and Management of the Urdaibai Biosphere Reserve (amended by Decree 139/2016, of 27 September, approving the Master Plan for the Use and Management of the Urdaibai Biosphere Reserve)
- the Regulatory Ordinance of the Regime of Use and Uses on the beach of Laga and Laida, of the City Council of Ibarrangeliu, of February 26, 2007.
Although globally the restoration project began in 1999 based on the results of the pilot experiment carried out in the area, the exposed regeneration program began its work on May 1, 2004 and ended on April 30, 2007.
However, since that date and until the present, study, control, maintenance, training and information tasks have continued to be carried out, on interventions, evolution of the ecosystem and activities carried out in the affected area.
http://www.euskadi.eus/contenidos/informacion/life_dunas/es_def/adjuntos/2005_2006.pdf
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Manu Monge Ganuzas
Senior Environmental Technician
Urdaibai Biosphere Reserve Service
Email: manu-monge@euskadi.eus
Phone: 944032366
