La restauration hydromorphologique des cours d`eau :

La restauration hydromorphologique des cours d’eau :
premiers enseignements du projet LIFE WALPHY
Namur – 15, 16, 17 octobre 2013
Formulaire de soumission
Type de communication souhaitée : Présentation orale
Titre de la communication : Interdisciplinary monitoring of an hydromorphological restoration of a Rhine anastomosing
channel. First results.
Auteurs:
ESCHBACH David1
SCHMITT Laurent1
TREMOLIERES Michèle2
GRAC Corinne2
FINAUD-GUYOT Pascal3
ZIMMERMANN Arthur1
LEJEUNE Quentin1
Affiliations:
1Université de Strasbourg. Faculté de Géographie et
d’Aménagement, 3 rue de l’Argonne, 67083
Strasbourg cedex, Laboratoire Image, Ville,
Environnement – LIVE UMR 7362 UDS-CNRSENGEES.
2Université de Strasbourg. Institut de Botanique, 28
rue Goethe, 67083 Strasbourg cedex, Laboratoire
Image, Ville, Environnement – LIVE UMR 7362 UDSCNRS-ENGEES.
3ICube, UMR 7357, Equipe Mécanique des Fluides,
Département Mécanique, 2 rue Boussingault, 67000
Strasbourg
Courriels:
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
Résumé (250 mots max):
The Upper Rhine hydrosystem exhibits a high biodiversity. Since mid-19th century, several engineering projects developed
for flood control, agriculture, navigation and hydropower, have drastically impacted aquatic and riparian habitats. In this
context, the specific alluvial species of the Rohrschollen natural reserve is declining. Its main watercourse, the
Bauerngrundwasser, an anastomosing channel of the Rhine, has now a constant and low discharge (under 0.1m3/s),
inducing a high rate of fine sediment deposition. During periods of high flow, the site is flooded but water has no energy
due to a dam’s backwater effect.
The LIFE+ project “Restauration de la dynamique des habitats alluviaux rhénans sur l’île du Rohrschollen”, managed by
the City of Strasbourg, plans to restore the hydromorphological and ecological functionality of the hydrosystem: bedload
dynamics, channel mobility, surface water-groundwater exchanges, renewal of pioneer ecosystems…Thus, the
Bauerngrundwasser will be reconnected to the Rhine by building a new upstream connection channel. Water input will
attain 80m3/s, leading to dynamic floods and making of this project one of the most ambitious for the French side.
To assess the efficiency of this restoration project, an inter-disciplinary monitoring is carried out and is based on the
comparison of pre- and post-restoration dynamics. It includes geomorphic and ecological studies. Especially, the
geomorphic focuses on topographic, cartographic, sediment transport, hydrological and hydrogeological data, as well as
the implications of the temporal trajectory of the system (historical study based on old maps, aerial photos and
sedimentological investigations). The ecological focuses on macrophytes, riparian vegetation and macrobenthos.