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| − | + | The Tiétar River, one of the tributaries if the Tajo River, has a basin area of 4459,1 km<sup>2</sup> and a lenght of 150 km. The gentle relief and the contribution of meltwater from Gredos´ mountain range makes the river wide, shallow, and braided. From its source to the Rosarito dam, the river is not regulated, and the flow is characterised by a natural hydrological regime. The river has a high charge-sedimentation capacity, and it transports materials of differnt granulometry from Gredos granite source reaches. Morphodynamic processes originate the succession of bars, mostly longitudinal and oblique to the flow direction. | |
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==Measures selection== | ==Measures selection== | ||
Revision as of 11:15, 23 June 2010
Tiétar. Proyecto de Permeabilización Piscícola del Azud de Protección del Viaducto de la Carretera N-502 sobre el Río Tiétar.
Key features of the case study
This project is part of the National Strategy for River Restoration developed by the Spanish Ministry of Environment and in this case, designed and implemented by the Confederación Hidrográfica del Tajo. Between 1985 and 1986 a viaduct for the N-520 highway was built over the Tiétar River. At the same time, a weir was constructed to protect the pillars of the viaduct. This mass concrete weir has a lenght of 120 meters and is 2 meters high. There are two drains at the bottom of the weir by which fish can not pass due to the great hydraulic power (> 150 watts/m3). Thus, cyprinid populations have seen reduced their chances for migrate upstream. The weir is also an obstacle for the transport of sediments, being altered the river morphodynamic at this site. To restore the longitudinal connectivity of the river without compromising the stability of the viaduct, a fish ramp was designed.
Site description
The Tiétar River, one of the tributaries if the Tajo River, has a basin area of 4459,1 km2 and a lenght of 150 km. The gentle relief and the contribution of meltwater from Gredos´ mountain range makes the river wide, shallow, and braided. From its source to the Rosarito dam, the river is not regulated, and the flow is characterised by a natural hydrological regime. The river has a high charge-sedimentation capacity, and it transports materials of differnt granulometry from Gredos granite source reaches. Morphodynamic processes originate the succession of bars, mostly longitudinal and oblique to the flow direction.
Measures selection
Success criteria
Ecological response
Hydromorphological response
Monitoring before and after implementation of the project
Socio-economic aspects
The most important restriction for the project design was that the stability of the viaduct´s pillars couldn´t be endangered. For this reason, the elimination of the weir (partial ot complete) was discarded in first place, as the weir controls stream energy.
Contact person within the organization
Extra background information
Documents from the project design (Ministry of Environment. Confederación Hidrográfica del Tajo):
- Project Report (Spanish) Media:Tietar_Project_Report.pdf
- Photographic Appendix Media:Tietar_Pictures_Appendix.pdf
- Hydrological study (Spanish) Media:Tietar_Hydrological_Study.pdf
- Hydraulic study (Spanish) Media:Tietar_Hydraulic_Study.pdf
- Environmental Integration (Spanish) Media:Tietar_Envionmental_Integration_of_the_works.pdf
- Safety conditions of the works (Spanish) Media:Tietar_Basic_study_of_health_and_safety_during_the_works.pdf
- Project plan (Spanish) Media:Tietar_Project_plan.pdf
References
