monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17...
TRANSCRIPT
![Page 1: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/1.jpg)
4 > 8 juinRecherches et actions au service des fleuves et grandes rivières
Integrative sciences and sustainable development of rivers LYON 2018
Monitoring of a sediment
replenishment operation:
The case of the Saint-Sauveur dam in the
Buëch River (Southern Alps. France)
G. Brousse ; M. Bertrand ; G. Arnaud-Fassetta ; F. Liébault ;
L. Borgniet ; G. Melun ; R. Loire ; J.R. Malavoi ; G. Fantino
![Page 2: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/2.jpg)
I.S.RIVERS 2018
• Research context
• Why restore - How to restore ?
• Monitoring approaches
• Hydromorphological evolution of the restored
reach
• Feedback and prospects
Outline
![Page 3: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/3.jpg)
I.S.RIVERS 2018
Geology dominated by sedimentary rocks with black marls
A hot spot of the Alpine biodiversity with a mosaic of ecological habitats
Multiple economic uses (irrigation, hydro-electricity. Hunting, fishing, tourism …)
Research context
SMIGIBA©
![Page 4: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/4.jpg)
I.S.RIVERS 2018
Human alterations of the physical fluvial
corridor :
• Gravel mining
> 3 Mm3 in the upper catchment
> 6 Mm3 in the lower catchment
• Flood protection and hydropower
equipments
River regulation (before 20th century)
Saint-Sauveur dam (1991 and 1992) => dredging
of 600,000 m3 of sediment
• Bedload has been strongly impacted
Why restore - How to restore ?
Rapid channel responses :
• Alluvial fan is aggrading upstream the reservoir
• Narrowing and degradation of the active
channel with downstream propagation
• Marly bedrock outcrops are observed along the
degraded reach
• A shift from a braided to a wandering pattern
![Page 5: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/5.jpg)
I.S.RIVERS 2018
THE REPLENISHMENT OPERATION
• September 2016: 1 million euros
• Dredging the alluvial fan of the Saint-
Sauveur reservoir
• Clearing alluvial bar
• Sediment replenishment downstream
of the dam (44,000 m3)
• 2,500 m3 by day (7 tip-truck)
• Limiting flood risk
• Stop incision
Why restore - How to restore ?
NEW RULES OF DAM EXPLOITATION
1997 : transparency for Q>80 m3/s
(without forecast)
2015 : transparency for Q>60 m3/s
(according to forecast on 24h)
Frequency and magnitude of
transparency are higher in order to
optimize sediment continuity
Right berm central berm left berm
« Point bar stockpile method » (Ock et al.. 2013)
![Page 6: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/6.jpg)
I.S.RIVERS 2018 Monitoring device
Database
Topography
Field surveys
Hydrology
Time lapse
• Grain-size sampling
• Marl outcrops
• Flood marks
• Bedload tracing with
active UHF RFID tags
• Sequential LiDAR
• Drone survey and SfM
• 2 cameras
• 1 photo / hour
• 6 months
OBJECTIVES :
CAPTURE THE GEOMORPHOLOGICAL AND BIOLOGICAL RESPONSES OF THE DEGRADED REACH TO THE ARTIFICIAL GRAVEL RECHARGE
• Floodgates hydrology
• Overflow wear hydrology
![Page 7: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/7.jpg)
I.S.RIVERS 2018
0
50
100
150
200
250
300
350
400
18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18
Q (
in m
3/s
)
Time
Monitoring device
Q10
Q2
REPETITIVE DATA ACQUISITION
5 Airborne LiDAR
1 SfM
3 bedload tracing inventory
3 field surveys
Hydraulic transparency
LiDAR
Sediment tracking
Field survey
SFM
RESULTS
![Page 8: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/8.jpg)
I.S.RIVERS 2018Hydromorphological evolution
CHARACTERIZATION – Just after restoration (September 2016)
![Page 9: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/9.jpg)
I.S.RIVERS 2018Hydromorphological evolution
CHARACTERIZATION – During flood (November 2016)
Berms erosion
Hydraulic transparency
![Page 10: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/10.jpg)
I.S.RIVERS 2018Hydromorphological evolution
CHARACTERIZATION – Just after flood (December 2016)
![Page 11: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/11.jpg)
I.S.RIVERS 2018Hydromorphological evolution
THE REPLENISHMENT SITE – Post flood (December 2016)
622
623
624
625
626
627
628
629
0 20 40 60 80 100
Altitu
de
(m
)
Distance (m)
1
1
2
3
2
3
SC
SC
Very high erosion on the central and on the right berm during flood
➔ 20,000 m3 (46% of initial berms)
Net sediment budget ➔ -11,000 m3
Post floodPost restoration
-14 000
-12 000
-10 000
-8 000
-6 000
-4 000
-2 000
0
2 000
LEFT CENTRAL RIGHT
MC
MC
Δz (m)
1
2
Vo
lum
e (i
n m
3)
Alt
itu
de
(in
m)
![Page 12: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/12.jpg)
I.S.RIVERS 2018Hydromorphological evolution
THE REPLENISHMENT SITE – Flood modelization
0; 0.5
0.5; 5
5; 10
10; 20
20; 30
30; 50
50; 70
70; 90
>90
• 2D Telemac model of the Q10 flood
(Durand-Gasselin. 2017)
• Field calibration (grain size and flood
marks)
Shaping of the secondary channel?
• A net limit between MC and SC
• Flow dividing
• Minimize erosion in SC
• Erosion of SC du to lateral and regressive erosion
• No linear erosion
• Too far of the flow axis
Bed shear stress (in N/m²)
![Page 13: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/13.jpg)
I.S.RIVERS 2018Hydromorphological evolution
622
623
624
625
626
627
628
629
-10 10 30 50 70 90 110
Altitu
de
(i
n m
)
Distance (in m)
1
2
3
SC
Post floodPost restoration 1 year later
Very small evolution during last year But the main channel erode
the right bank
Net sediment budget ➔ -150 m3
0 30 60 90 12015m
THE REPLENISHMENT SITE – One year later (September 2017)
1
2
3
Δz (m) MC
![Page 14: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/14.jpg)
I.S.RIVERS 2018
Aggradation max in the 2.5 km
downstream reach
Global net deposition
Hydromorphological evolution
THE DOWNSTREAM REACH – Longitudinal profile
-1
-0,5
0
0,5
1
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500
-1
-0,5
0
0,5
1
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500
Talweg
After flood After 1 year
1
2
Δ(m
)Δ
(m)
Active channel
Replenishment
zone
POST FLOOD N+1
Min -0.85 -0.67
Mean 0.12 -0.08
Max 0.76 0.18
SD 0.34 0.11
POST FLOOD N+1
Min -0.86 -0.14
Mean 0.06 0.002
Max 0.60 0.21
SD 0.22 0.04
![Page 15: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/15.jpg)
I.S.RIVERS 2018Hydromorphological evolution
THE DOWNSTREAM REACH – Sediment budget
Hypothesis: Sediments from eroded berms
have been exported to the downstream reach
2,500 m
REPLENISHMENTZONE
DOWNSTREAM REACH
Berms erosion = 20,000 m3
INPUT STORAGE CHANGE OUTPUT
500 m
Bedload deposit = 9,000 m3
DEM differenceBedload
calculation
DAM
I = ΔS + O
46,000 m3 34,000 m3 12,000 m3
Bedload passing = 26,000 m3
35
,00
0 m
3
![Page 16: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/16.jpg)
I.S.RIVERS 2018Hydromorphological evolution
THE DOWNSTREAM REACH – Travel distance from berms erosion
n = 148
Recovery rate = 68%
Mean travel distance =1,150
Max = 3,240 m
Only informations upstream the dam
0
5000
10000
15000
20000
25000
30000
35000
0 500 1000 1500 2000
Vo
lum
e (m
3)
Distance (m)
Cumulative sediment budget
Bermserosion
20,000 m3
Distance travel from berms erosion: [0; 1600] m
![Page 17: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/17.jpg)
I.S.RIVERS 2018Feedback and prospects
In one year: Hydromorphological objectives are achieved
• Great erosion of initial berms ➔ sediment input to the downstream
reach
• Net aggradation on the 6 km downstream reach (main channel and
active channel)
• Change are more important in the upper part (2.5 km) o Aggradation is greater
o Main channel erosion
Real impact of hydraulic transparency which permits a net gain of the
sedimentary budget
![Page 18: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/18.jpg)
I.S.RIVERS 2018Feedback and prospects
Exploitation feedback
Positive
• Monitoring show the efficiency of the replenishment operation
• Efficiency is link to ideal conditions (hydrology and exploitation)
• New knowledge about the area of influence of hydraulic transparency
Negative
• Shaping of a secondary channel is not a good solution in this site
• Left berm are now non erodable for frequent flood
Prospects 2018-2020
• Distinguish impact of frequent flood with or without hydraulic
transparency
• Monitoring of the channel degradation
• Monitoring of the left berm pushing in the active channel (september
2018)
![Page 19: Monitoring of a sediment replenishment operation · 18/08/16 26/11/16 06/03/17 14/06/17 22/09/17 31/12/17 10/04/18 19/07/18 m 3) Time Monitoring device Q 10 Q 2 REPETITIVE DATA ACQUISITION](https://reader034.vdocument.in/reader034/viewer/2022042301/5ecc892f4a9a387d8744ff4f/html5/thumbnails/19.jpg)
I.S.RIVERS 2018
Thank you for your attention
UFR GEOGRAPHIE HISTOIRE ECONOMIE ET SOCIETES (GHES)
UMR 8586 PRODIG
Guillaume BrousseDoctorant en Géographie
Bâtiment Olympe de Gouges – Case courrier 70015 rue Thomas Mann – F – 75205 Paris Cedex 13+33 (0)6 77 18 97 98www.univ-paris-diderot.fr | www.prodig.cnrs.frguillaume.brousse@[email protected]