Assessment of consequences of sediment deficit on a gravel river bed downstream of dams in restoration perspectives: application of a multicriteria, hierarchical and spatially explicit diagnosis

A.J. Rollet 1 H. Piégay 2 S. Dufour 3 Gudrun Bornette 4 Henri Persat 5
1 LETG - Caen - Littoral, Environnement, Télédétection, Géomatique
LETG - Littoral, Environnement, Télédétection, Géomatique
3 LETG - Rennes - Littoral, Environnement, Télédétection, Géomatique
LETG - Littoral, Environnement, Télédétection, Géomatique
4 Écologie Végétale et Zones Humides
LEHNA - Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés
5 Biodiversité des Écosystèmes Lotiques
LEHNA - Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés
Abstract : As regards river restoration, it is fundamental to better link human pressures and environmental responses and to take into consideration not only target species or habitat but diverse ecological elements. This permits to assess sustainable restoration plan, especially concerning sediment augmentation below dams. The use of a hierarchical multicriteria approach on the Ain River permits us to assess a diagnosis of sediment deficit impact integrating several morphological (channel shifting, river bed degradation and river bed coarsening) and ecological components (Riparian and floodplain lake and fish communities). Our diagnosis also integrates a temporal and spatial approach better to link human pressures and environmental responses and to identify the dam effects amongst other drivers (e.g. grazing decline and channel regulation). The results confirm causality links between sediment deficit and slight channel bed degradation (0.01m.year-1) or channel bed paving and thus highlight the impact of the dam on the drying of the riparian forest and on former channel community. However, the relationship between incision and reduction in active channel lateral mobility is more difficult to establish. The role of sediment deficit in the current variability of the riparian regeneration capacity and, thereby, landscape diversity along the lower valley remains unclear. This study also confirms the relevance of using different ecological indicators, notably because all components present different adjustment time scales, whereas some of them are more sensitive to other impacts.
Type de document :
Article dans une revue
River Research and Applications, Wiley, 2014, 30, pp.939-953. 〈10.1002/rra.2689〉
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Soumis le : lundi 23 février 2015 - 11:33:18
Dernière modification le : mardi 24 avril 2018 - 01:47:44

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A.J. Rollet, H. Piégay, S. Dufour, Gudrun Bornette, Henri Persat. Assessment of consequences of sediment deficit on a gravel river bed downstream of dams in restoration perspectives: application of a multicriteria, hierarchical and spatially explicit diagnosis . River Research and Applications, Wiley, 2014, 30, pp.939-953. 〈10.1002/rra.2689〉. 〈hal-01119447〉

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