Case study:Robledo de Chavela dam removal

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Location: 40° 30' 18.03" N, 4° 14' 4.26" W

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Project overview

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Status	Complete
Project web site
Themes	Social benefits, Water quality, Urban
Country	Spain
Main contact forename	Rincón Sanz
Main contact surname	Gonzalo
Main contact user ID
Contact organisation
Contact organisation web site
Partner organisations
Parent multi-site project
This is a parent project encompassing the following projects	No

Moment of the demolition of Robledo de Chavela dam. The first photo shows the dam before its removal. The second picture shows the demolition moment and the third the state of the dam after demolition. Photo Credits: Ministry of Agriculture and Fishing, Food and Environment (MAPAMA).

Project summary

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The removal of the Robledo dam was a milestone as to be the highest dam demolished in Spain, and possibly, in Europe.

The work carried out, besides the removal of the dam wall, consisted of the extraction and relocation of sediments, the capture and transfer of 4500 specimens of native fish, delimitation of the channel with riprap, slope profiling and reforestation of the riverbank.

The dam was demolished on September 29, 2014, by the use of 1.2 tons of explosives. More than 9,000 m3 of concrete from the wall of the dam were demolished.

Monitoring surveys and results

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Due to the problems of sediment contamination stored upstream of the dam, a study was carried out prior to the removal in order to make a diagnosis of the sediments and their treatment. A plan is implemented to remove some of these sediments and place them in higher areas where they were confined and stabilized by planting native vegetation. Two years after the removal of the dam, a monitoring plan was conducted to measure:

- Physicochemical parameters of water as temperature, dissolved oxygen,

conductivity and pH.

- Habitat availability.

- Quality of the riparian forest.

- Flora (macrophytes) and fauna (macroinvertebrates and fish) present in the river, as well as exotic species.

The fish community in the Cofio River near the Robledo dam is: Rainbow trout (Oncorhynchus mykiss), Iberian barbel (Luciobarbus bocagei), chub (Squalius pyrenaicus), calandino (Squalius alburnoides) and Iberian gudgeon (Gobio lozanoi), being Squalius alburnoides the dominant specie. All are native species of the Tajo River Basin except from the rainbow trout that is exotic and comes from sport fishing.

Sampling points were determined both upstream and downstream from where the dam was located. The main results of this monitoring show clear signs of recovery in the river reach affected by the presence of the dam, with some differences between the areas that were located upstream and downstream of the dam.

Lessons learnt

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The removal of the Robledo dam stands out as an example of participatory management, in which the importance of administrative coordination between different social agents is evidenced.

The Robledo dam removal will promote the recovery of altered river processes as a consequence of the construction, exploitation and abandonment of the dam. It will therefore contribute to the improvement of the ecological status of the Cofio River and the native fish populations in this river.

A monitoring program was carried out after the dam removal (in August 2016) showing environmental improvements in the river after the removal. The importance of performing this monitoring before and after the dam removal is emphasized in order to quantify the effects that this type of actions have on the river.

Image gallery

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Catchment and subcatchment Select a catchment/subcatchment Site Edit site Name WFD water body codes WFD (national) typology WFD water body name Pre-project morphology Reference morphology Desired post project morphology Heavily modified water body No National/international site designation Local/regional site designations Protected species present No Invasive species present No Species of interest Dominant hydrology Dominant substrate River corridor land use Average bankfull channel width category Average bankfull channel width (m) Average bankfull channel depth category Average bankfull channel depth (m) Mean discharge category 0.1 - 1.0 m³/s Mean annual discharge (m3/s) 0.750.75 m³/s <br />750 l/s <br /> Average channel gradient category Average channel gradient Average unit stream power (W/m2) Project background Edit project background Reach length directly affected (m) Project started 2014/09/29 Works started Works completed Project completed 2014/09/29 Total cost category 100 - 500 k€ Total cost (k€) 280280 k€ <br />280,000 € <br /> Benefit to cost ratio Funding sources Cost for project phases Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname Investigation and design Stakeholder engagement and communication Works and works supervision Post-project management and maintenance Monitoring Supplementary funding information There is a total budget of €1.5 million which includes the elimination of the dam and the renaturalization of the environment. Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Barriers to fish migration Hydromorphology Continuity for organisms, Continuity of sediment transport, Quantity & dynamics of flow Biology Fish: Abundance, Fish: Species composition Physico-chemical Other reasons for the project Heavy metal pollution & This dam has never fulfilled the purpose for which it was designed, So the only management option, for technical, safety and environmental reasons, was its removal. Measures Edit Measures Structural measures Bank/bed modifications Dam removal, extraction and relocation of sediments, Delimitation of the channel with riprap, slope profiling, Reforestation of the riverbank Floodplain / River corridor Planform / Channel pattern Other Non-structural measures Management interventions Capture and transfer of fish Social measures (incl. engagement) Other Monitoring Hydromorphological quality elements Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Physico-chemical quality elements Edit Physico-chemical quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Any other monitoring, e.g. social, economic Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents Additional links and references Edit links and references Link Description http://europe.wetlands.org/publications/river-fragmentation-analysis-spain/ A link on the Wetlands International website to a document that describes the project. http://www.ecohidraulica.com/ All information on this page is copied from the document mentioned above which is written by Ecohidráulica, S.L. Supplementary Information Edit Supplementary Information References Amor Cortés, J. (2016). Emisiones de gases de efecto invernadero en la demolición de la presa de Robledo de Chavela y la restauración ambiental de los terrenos afectados. Final Master Degree dissertation. Confederación Hidrográfica del Tajo (2009). Diagnóstico y Propuesta de Tratamiento de los Sedimentos del Embalse de Robledo de Chavela en el río Cofio (Madrid). Estrategia Nacional de Restauración de Ríos. Confederación Hidrográfica del Tajo (2014). Derribada la presa de Robledo de Chavela (Madrid), sobre el río Cofio, la más alta desmantelada en España con casi 23 metros de altura. Press release from 29/09/2014 Confederación Hidrográfica del Tajo (2016). Seguimiento del estado ecológico del Río Cofio tras la demolición de la presa de Robledo de Chavela. Headwaters Economics (2016). Dam removal: case studies on the Fiscal, Economic, Social and Environmental benefits of dam removal. Industrial Economics Inc. (2015). Economic & Community Benefits from Stream Barrier Removal Projects in Massachusetts (MA). Massachusetts Department of Fish and Game, Division of Ecological Restoration. Ollero Ojeda, A. (2015). Guía metodológica sobre buenas prácticas en restauración fluvial. Manual para gestores.