Re-activation of the fluvial
dynamics of the Rhone river,
from complete harnessing back
to channel shifting procedures
Atelier de géomorphologie fluviale Gaydou, le 8 Juin 2011
• 1880-1920 : Girardon’s dykes
Harnessing the Rhone river (1880-1920)
The 1878 law declares Rhone’s improvements works as public utility. Almost
all the Rhone river course is harnessed, in majority downstream of Lyon.
78% of the « vieux Rhone » length is harnessed (between 45 et 100%)
The aim is to improve navigation conditions : stabilization of channel course,
concentration of fluxes in a unique arm, increase channel depth, turn
dangerous sections (cross riffles) into safer by changing the riffles orientation
Girardon dikes building,
Collection Dürrenmatt -MDFR
Harnessing the Rhone river (1880-1920)• 1890-1920 : Girardon’s dikes impacts
Collection Dürrenmatt, MDFR
Impacts of the two generations of civil engineering
works :- Channel has no more lateral mobility
- The topographic level of the river margins raised
-The bypassed discharge decreased
The Rhone river conditions :
-The changing of softwood forest into hardwood forest
- The side arms’s number and depth decreased
-The water level worsening during flood
- The alluvial ecosystems disappeared
The dams constructions on the tributaries, the erosion decreasing and the
sediments extractions induce fine sediments decreasing in the Rhone channel
while sediment balance is positive on the margins.
Gaydou, 2009
Works phase applied to Pont-Saint-Esprit
Girardon dike and
groynes
Submersible dyke
National Rhone Company,
2010
0
100
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400
500
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700
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1000
24-Sep 24-Oct 23-Nov 23-Dec 22-Jan 21-Feb 23-Mar 22-Apr 22-May 21-Jun 21-Jul 20-Aug 19-Sep
Dail
y F
low
(m
3/s
)
First results
National Rhone Company,
2010