Nansa River. Morphological and functional restoration of the Nansa River at Muñorrodero

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Nansa River. Morphological and functional restoration of the Nansa River at Muñorrodero

Factsheet: Nansa River. Morphological and functional restoration of the Nansa River at Muñorrodero

Country ES
River Name Nansa
Site Name Nansa River. Morphological and functional restoration of the Nansa River at Muñorrodero
River Characterisation
    River typology
    Location (Lat Lon) 43.3641273479357, -4.48894500732422
    Altitude lowland: < 200 m
    Catchment area medium: > 100 - 1000 km2
    Geology Calcareous
    National code/
    River type name

    Biological quality elements
    Ecosystem Services
    EU Directives
    Project size -1
    Approximate costs > 1 000 000 Euros
    Synergy Proximity of the village of Muñorrodero. Flood protection.
    Status Realised
    Period of realization 01/09/2009 - 01/05/2010
    Implemented by Confederación Hidrográfica del Cantábrico - Comisaría de Aguas. Executed by TRAGSA

    Key features of the case study

    The lower reach of the Nansa River was channelized in 1995 in Muñorrodero. As a result of this, its former right branch lost its connection with the main channel, although its morphology remained virtually unchanged. This situation led to a loss of aquatic and riparian habitats.
    The project was designed by the Confederación Hidrográfica del Cantábrico, executed by TRAGSA with the financing of the Spanish Ministry of the Environment. The objective was to restore the former morphology and fluvial dynamics in the Nansa River.

    Site description

    Nansa River has a length of 3200 meters and a basin surface of 411 Km2. The channel width is around 10 meters. The river discharge is around 12,5 m3/s, and the stream power of 245.8 kg m s-3. The substrate consists of sandstone and limestone. The vegetation is composed by a mixed riparian forest (Alnus glutinosa and Salix sp.) and grassland. Among the fish species we can find Salmo salarand Petromyzon marinus.

    Measures selection

    The main objective was to restore the fluvial dynamics and reconnect a former secondary channel . The proximity of Muñorrodero village imposed some constraints, as flood protection measures were also necesary. Thus, a levee was constructed with bioengineering techniques. The former branch was conceived as a high flow channel, while the main channel is expected to discharge water with low flows. this measure would help to disipate the energy of the high flows, increase the retention of water in the watershed, and increase the diversity of riparian habitats, as the hydrological and morphological conditions vary from the main channel to the side arm.
    Alongside to the restoration measures, two footbridges were built and paths were arranged for enable recreational use of this area.

    Construction of the new levee for flood protection with bioengineering techniques
    The side arm once restored
    Plan of the main actions

    Success criteria

    The ideal situation was to achieve a self- sustainable braided channel morphology.

    Ecological response

    Hydromorphological response

    Monitoring before and after implementation of the project

    Reconstruction of geomorphic evolution, habitat assessment and hydraulic modelling were done in the early stages of project design. However no monitoring program was designed or has been implemented.

    Socio-economic aspects

    The total budget was of 1.447.000 €, financed by the Spanish Ministry of the Environment. The presence of meadows, fields and houses involved socio-economic restrictions when designing the restoraion project. flood protection measures were linked to the reconnection of the side channel.

    Contact person within the organization

    Rubén Santos Alonso
    Grupo de Cauces - Tragsa
    Centro Cívico
    c/ Comandante Caballero s/n
    33005 Oviedo

    Extra background information


    Related Measures

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