The azudes like that of Trankaz, also known as derivation dams are hydraulic constructions that are placed in the water courses with the purpose of temporarily or permanently raise their level, but without storing a large amount, as with a dam.
Are Design is much simpler than that of dams and, in general, they are built in rivers or streams with the objective of deriving, regulating or distributing the flow of water. The problem is that over time, these constructions are obsolete and can prevent the correct river circulation.
Partial demolition of Trankaz Azud
The Basque Water Agency – Ura has carried out the partial demolition of the AZUD of Trankaz y The restoration of the right bank of the Portu Arroyo, in the municipality of Hernani (Gipuzkoa). This action, aligned with the objectives of recovery of the good ecological state of the Euskadi rivers marked in hydrological planning, seeks to improve river connectivity and favor the biodiversity of the aquatic ecosystem.
The works have lasted 1.5 months, distributed in two stages of execution and the realization of autumn plantations. The investment has promoted € 55,192.18. The azud of Trankazoriginally built to supply the Santa Barbara de Hernani quarry, it was disused since 2009. His permanence in the channel meant a barrier to the fish fauna and An obstacle to the natural circulation of sedimentsaffecting the river dynamics of the Port Arroyo, tributary of the Urumea River.
Natural water dynamics
The intervention has consisted of the partial demolition of AZUD, eliminating 5.6 meters from its structure to Allow the free circulation of water and fish. A small section has been maintained on the left bank to guarantee the stability of the land and the protection of a sanitation infrastructure.
In addition, the restoration of the right bank of the stream has been restoled through the elimination of obsolete structures, the regeneration of the land and the revegetation with native species. These works will contribute to improving the quality of river habitat and strengthening the ability to adaptation of the ecosystem before possible extreme events.
The demolition of disused dams and azudes such as Trankaz, It is part of the river restoration strategies promoted by URA and European environmental institutions. The elimination of these barriers facilitates the migration of fish species, allowing their access to reproduction and food areas; It enables natural sediment transport (improving the structure of the channel and reducing erosive processes); It increases water quality by favoring greater oxygenation and reducing the accumulation of organic matter and contributes to Recovery of the river landscape and biodiversity of aquatic and riverside ecosystems.