Case study:La Gotera dam removal

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Location: 42° 44' 13", -5° 38' 41"
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Project overview

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Status Complete
Project web site
Themes Environmental flows and water resources, Habitat and biodiversity, Hydropower, Hydromorphology
Country Spain
Main contact forename Rincón Sanz
Main contact surname Gonzalo
Main contact user ID
Contact organisation Duero River Basin District
Contact organisation web site
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Image of the removal works of La Gotera dam. Photo Credits: Ministry of Agriculture and Fishing, Food and Environment (MAPAMA).

Project summary

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The Works of removal started in September 2011 by the Duero River Basin District and within the framework of the National Strategy of River Restoration (NSRR).

The slope between the river and the banks required the construction of a ramp so that the machines could access to the river. Due to the impossibility of removing the material from the ramp once the work was finished, material from other restoration activities in other river reaches was used. The native vegetation of the area was respected during the works of removal. In addition, it will serve to fix the ramp that allows the approach of the machines to the river.

Prior to the removal, a capture of the fish specimens located upstream of the dam was performed and subsequently released in the same river away from the intervention. A high abundance of fish was observed.

A volume of 1,068 m3 of debris was removed during the works. The concrete from the bypass channel and the dam was removed in the last phase of the work. All elements that are strange to the river like the concrete or metallic remains were removed from the river and moved to authorized dump sites.

With this removal, 15 kilometers of river that previously were interrupted by the dam has been reconnected. Barely a month after the removal of the obstacle, the river has recovered its natural course

Monitoring surveys and results

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The information regarding the monitoring of La Gotera dam removal is very scarce. A study was carried out prior to the demolition of the dam and another one a year later. Three points were sampled: a reference point upstream the dam, other near the dam wall and a third one downstream the dam. The fish samplings yielded no significant results. However, all macroinvertebrate indices did show an improvement, especially in the sampling point downstream of the dam.

Lessons learnt

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The removal of this dam is an example that the performance of these actions, together with the availability of an adequate flow, generates good results in a short period of time.

It will be the river with its high flows that finally does the restoration work. The river mobilizes the sediments naturally the year after the removal


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Catchment and subcatchment



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 10 - 100 m³/s
Mean annual discharge (m3/s) 22.5
22.5 m³/s
22,500 l/s
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m)
Project started 2011/09/01
Works started
Works completed
Project completed
Total cost category 100 - 500 k€
Total cost (k€) 125
125 k€
125,000 €
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



Reasons for river restoration

Mitigation of a pressure Barriers to fish migration
Hydromorphology Continuity for organisms, Continuity of sediment transport
Biology Fish: Abundance
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications Dam removal, Reconnection of river
Floodplain / River corridor
Planform / Channel pattern
Other
Non-structural measures
Management interventions capture of fish prior to the works
Social measures (incl. engagement)
Other


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

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

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



Additional documents and videos


Additional 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.
http://www.youtube.com/watch?v=iZeJ28uDIW4 More information about La Gotera dam removal process

Supplementary Information

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References

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.

Rodríguez Muñoz, I., Santillán Ibáñez, JI., Huertas, R. (2011). Excursión del I Congreso Ibérico de Restauración de Ríos. León.