Restoration of the Oka River’s upper estuary, part of the Urdaibai Biosphere Reserve

    Solution ID
    Description of solution
    Summary (Challenges; Objectives)

    The main objectives of the actions implemented in the upper estuary of the Oka River are: (i) Improve the resilience of the estuarine ecosystems to the impacts of climate change, such as sea level rise and changes in the water regime; (ii) Increase local biodiversity thanks to the recovery of part of the ecosystem's functionality; (iii) Increase the sustainable public use of the natural space of the Urdaibai Biosphere reserve.Restoration activities aiming to recover the previously existing marshland have been implemented in the upper estuary of the Oka River, including the permanent flooding of the Barrutibaso area part of the upper estuary. Moreover, the functionality of part of the original intertidal channel of the Oka River’s lower section has been recovered. As part of these restoration activities, some of the dykes and other artificial barriers have been removed to improve the estuary renaturalisation, while embankments have been constructed to create lagoons that will become intertidal zones in the future. The restoration of marshlands formerly drained for sanitary reasons can help the estuary to face climate change. Marshes, in addition to protect against the effects of sea level rise, play an important ecological role providing new habitats to various species of amphibians and birds and improving their adaptation capacity. Moreover, the permanent presence of brackish water favours the elimination of some invasive species (e.g. Baccharis halimifolia).The restoration project also included other interventions and activities:<ul><li>The construction of a 14 km pathway network and of a pedestrian and cycling bridge connecting the neighbouring municipalities among each other and to the Oka river estuary, aiming to facilitate sustainable visit of the area;</li><li>The development of tools for environmental education, the most notable being a smartphone application providing information on the habitats, species and culture of the area. Moreover, panels have been installed providing on-site information on local habitats and species.</li><li>Eradication of invasive species (as Baccharis halimifolia and Cortaderia selloana) in an area of approximately 700 ha of the estuary.</li></ul>

    Success factors / lessons learnt

    The newly constructed pathway network has facilitated the connection of different municipalities through sustainable transport (bicycle and walking). Besides improving the sustainable public use of the estuary area it also contributed in raising awareness on the restoration project.Some of the municipalities included in the area where the restoration measures have been implemented did not take part into the project, thus posing some limitation to its complete development. Therefore, some phases of the project (mainly dealing with removal of some of the dams) are still to be implemented.Moreover, the ingrained sense of ownership of the people in the area to be restored has made the implementation of some of the project activities difficult. The 1998 Coastal Law establishes an area 100m wide on both sides of the river, where land owners can make objections to actions planned. For this reason some actions included in the restoration project have not been implemented, yet. Nevertheless, negotiations are continuing in order to make sure that the totality of the project is implemented.

    Location Latitude
    Location Longitude
    Comment on location

    Urdaibai Biosphere Reserve, País Vasco, Spain

    Ecosystem (s) impacted
    Hazard(s) concerned
    Other challenges
    Climate adaptation
    International classification
    Sendai Frameword priorities addressed
    Priority 3. Investing in disaster risk reduction for resilience
    Temporal aspects
    Design life time of the action
    More than 10 years
    Financial aspects

    The project has been completely funded by the Department of Environment, Land planning and Housing of the Government of Basque Country. The overall amount of the project budget is about 2.5 million euro.

    Participatory process
    Partcipatory approaches/ community involvement

    The restoration project of the Oka River’s upper estuary included the organisation of several meetings with different stakeholders, such as the municipalities located in the area, landowners and environmental associations.

    Risk reduction