hydropeaking and minimum flow : the french approach. p. baran cis ecostat - hydromorpholgy workshop...
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Hydropeaking and minimum flow : the French approach.
P. Baran
CIS ECOSTAT - HYDROMORPHOLGY WORKSHOP
12th and 13th June 2012 - Brussels
Pôle Ecohydraulique
Total amount of water per year in stream : 200 billion m3 In 2009, 33,4 billion m3 in total collected :
64% for the production of electricity 17% for drinking water 10% for the industry 9% for irrigation
The water storage has been developed for : irrigation, hydropower generation drinking water
126 000 samples of water whose 80,000 for agricultural use
French context of water storage
Production : Between 60 to 70 TWh for hydroelectricity (550 TWh of total
production), 50% of the production by hydropower plants managed by hydropeak
with to type of schemes : organized in line (eg: Durance, Dordogne, Truyère).
organized with high-head storage (Alpine and Pyrenean mountains)
French context for hydroelectricity
French approach
Identification and quantification of changes of flow regime with two priorities : Low flow Hydropeaking
Mitigation measures to increase low flow value (large scale (2014)) and/or to change locally the hydropeaking management.
Garonne - Saint-Béat - 2006
0.0
23.6
47.2
70.8
94.4
1/1 1/2 4/3 4/4 5/5 5/6 6/7 6/8 6/9 7/10 7/11 8/12Date
Débi
t (m
3/s
)
Hydropeaking
Focus on hydropeaking
More than 150 hydroelectric schemes managed by hydropeaking in France.
≈ 3000 kms of streams concerned by hydropeaking.
7
Garonne - Saint-Béat - 2006
0.0
23.6
47.2
70.8
94.4
1/1 1/2 4/3 4/4 5/5 5/6 6/7 6/8 6/9 7/10 7/11 8/12Date
Débi
t (m
3 /s)
Corrèze - Corrèze - 2006Hydrologie naturelle
0.0
5.6
11.2
16.8
22.4
1/1 1/2 4/3 4/4 5/5 5/6 6/7 6/8 6/9 7/10 7/11 8/12Date
Déb
it (
m3 /s
)
Comparaison des débit moyens journaliers (QMJ) et des débits à pas de temps variable (QTVAR) à Argentat.
Comparaison des débit moyens journaliers (QMJ) et des débits à pas de temps variable (QTVAR) à Argentat.
Analysis of flow regime
The French approach
1. Identifications of flow modifications induced by hydropeaking
8
Characterization of fish habitats by hydraulic models and habitat preference curves of species and life-stages
89
90
91
92
93
94
95
96
97
98
99
0 500 1000 1500 2000 2500 3000
Distance à partir de l'aval (m)
Alt
itu
de
rela
tive
(m
)
Thalweg
Modèle 20 m3/s
Mesure 20 m3/s
Modèle 30 m3/s
Mesure 30 m3/s
Modèle 117 m3/s
Mesure 117 m3/s
Modèle 200 m3/s
Mesure 200 m3/s
Modèle 303 m3/s
Mesure 303 m3/s
2. Identifications of habitat alterations related to the flow modifications induced by hydropeaking
The French approach
9
Surface en eau des 7 frayères
15000
17000
19000
21000
23000
0 50 100 150 200 250 300
Débit (m3/s)
Sur
face
(m²)
Dordogne - Argentat - 2008
0
50
100
150
200
250
300
350
400
1/1 16/1 31/1 15/2 1/3 16/3 31/3 15/4 30/4 15/5 30/5
DateD
ébit
(m
3 /s)
The French approach
3. Proposal of mitigation measures and assessment
Approach based on hydraulic models and habitat mapping
Index of hydrological perturbation
Method to characterize the hydrological disturbance
Data base : gauging stations Hourly flow analysis
Identification of each flow variations
Differentiation between the hydropeak and natural variations
Garonne - Saint-Béat - 2006Affected by hydropeaking
0.0
23.6
47.2
70.8
94.4
1/1 1/2 4/3 4/4 5/5 5/6 6/7 6/8 6/9 7/10 7/11 8/12Date
Dis
char
ge
(m3 /s
)
Method to characterize the hydrological disturbance
number of hydropeaks, Each hydropeak is
characterized by : base flow, maximum flow, range, rate of change,
Method to characterize the hydrological disturbance
For each year : Number of hydropeaks Statistical characteristics of :
base flow, maximum flow, range, rate of change,
Base flowRangeRate of change
Nu
mb
er o
f h
ydro
pea
ks
Maronne - Basteyroux - 2006
0.0
20.3
40.6
60.9
81.2
1/1 1/2 4/3 4/4 5/5 5/6 6/7 6/8 6/9 7/10 7/11 8/12
Date
Dic
har
ge
(m3 /s
)
Garonne - Saint-Béat - 2006
0.0
23.6
47.2
70.8
94.4
1/1 1/2 4/3 4/4 5/5 5/6 6/7 6/8 6/9 7/10 7/11 8/12Date
Dis
char
ge
(m3/s
)
Dordogne - Argentat - 2006
0
107
214
321
428
1/1 1/2 4/3 4/4 5/5 5/6 6/7 6/8 6/9 7/10 7/11 8/12Date
Dis
char
ge
(m3 /s
)
Daily hydropeaks
Hourly hydropeaks
Weekly hydropeaks
Characterization of hydrologic perturbation: Construction underway of an indicator of hydrologic
perturbation due to hydropeaking events.
Level Colour Levels of hydrologic perturbation
due to hydropeaking events
0 Hydrology natural or hardly disturbed.
1 BlueNoticeable hydrologic perturbation.
2 Green Hydrologic perturbation marked.
3 YellowHydrologic perturbation very marked.
4 Orange Severe hydrologic perturbation.
5 RedVery severe hydrologic perturbation.
Based on discriminant analysis :
-base flow,-maximum flow,-range,-rate of change,- number of hydropeaks
Characterization of hydrologic perturbation:
The index just evaluate the hydrological perturbations and not ecological effects
The index allow to analyse the evolution of the perturbation along a stream or between years.
Saint-Béat - 2006
Chaum - 2006
Valentine - 2006Upstream
Downstream
Global situation in France:
80 stations were analysed in 50 french streams. 58% of stations with strong alterations of flow regime
Impact of hydrological perturbations on fish habitat
Two types of impacts on fish habitat depending on morphology of stream.
Impacts on fish habitat
Mountain steep stream : hydraulic conditions during
high flow
Effects of hydropeaking management during life-stages of fish
Impacts on fish habitat
Lez river (MD : 1 m3/s)
Hydrologic perturbation very marked, maximum discharge 4 m3/s (≈4 times MD), between 150 and 300
hydropeaks per year.
Two types of impacts on fish habitat depending on morphology of stream.
Impacts on fish habitat
Braided streams : Hourly variations on wetted perimeter dewatering fish habitats on shallow shoreline areas and trapping fry in disconnected
secondary channels
Impacts on fish habitat
Monitoring two streams (MD :107 m3/s; MD : 20 m3/s)
Hydrologic perturbation marked or very marked, maximum discharge 340 m3/s (≈3.2 times MD), between 100 and 240 hydropeaks per year.
La Dordogne à Argentat en 2006
0.0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
Débit de base (proportion du module)
Am
plit
ud
e (
pro
po
rtio
n d
u m
od
ule
)
> 1
0.25 - 0.5
0 - 0.25
Gradient (module/heure)
Line of lakes and hydropower plants
La Maronne à Basteyroux en 2006
0.0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
Débit de base (proportion du module)
Am
plit
ud
e (
pro
po
rtio
n d
u m
od
ule
)
0.5 - 1
0.25 - 0.5
0 - 0.25
Gradient (module/heure)
Hydrologic perturbation very marked, maximum discharge 35 m3/s (≈1,8 times MD), between 150 and 300 hydropeaks per year.
Impacts on fish habitat
Monitoring ecological effecfs of hydropeaks Dewatering of salmonid redds and mortality of eggs (30% of the total
redds). Trapping of fry in disconnected secondary channels and mortality
(6000 fry/year on 6 kms of stream).
During a hydropeak Back to base flow
Mitigation measures
Two types : Changes on hydropeaking management :
Number of hydropeaks during specific biological periods, Base flow, range, maximum flow, rate of change
Changes on stream morphology : Connectivity of secondary channels, River banks Topography of gravel bar
Mitigation measures
Base flow increased : from 0.5 m3/s to and 4 m3/s (5-20% of MD) in winter and spring, 1 m3/s the rest of the
year From 10 m3/s to 30 m3/s (28% of MD) in winter and spring (15/11-15/06), 10 m3/s the
rest of the year.
Maximum discharge limited : to 35 m3/s (less than 2 times MD), if possible, in spring (15/03-15/06). to 190 m3/s (less than 2 times MD), if possible, in spring (15/03-15/06).
Discharge downramping rate of change limited : to 20 m3/s/h in spring (15/03-15/06). to 30 m3/s/h all year round.
Work on morphology to ensure permanent supply of secondary channels.
Mitigation measures
Efficiency: Only ≈ 5% salmonid redds dewatered, instead of 30% without base
flow increase.
Significant decrease of fry mortality in connected secondary channels.
MaronneBras RD de l'Hospital
0
86.4
44.8
66.1
123.1
0
20
40
60
80
100
120
140
≤ 2005 2006 2007 2008 2009
Den
sit
és d
e 0
+p
ou
r 1
00 m
²
Effects on electricity production
There were compensations for the losses of electricity production. In general, losses of production varied between 0,5 % to 2% of the total potential of peak production.
They remained quite limited because of the line organization. Only the production of the last hydropower plant is really affected.
All decisions of flow changes were made in consultation with the electricity company
Minimum flow
Evolution of low flow Analysis of the evolution of low flow at large scale
during the 3 last decades (Guintoli and Renard, 2010). Volume Duration Time (begining and end)
Evolution of low flow Significant evolution of low flow conditions.
Fish communities and low flow
Changes in fish communities in relation to
low flow conditions
Fish communities and low flow
Fish communities and low flow
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
QMNA (m3/s)
Bio
mas
ses
de
TR
F (e
n g
)
0
500
1000
1500
2000
2500
3000
3500
0 0.1 0.2 0.3 0.4 0.5
QMNA (en m3/s)
Bio
ma
ss
es
de
TR
F (
en
g)
French approach
The French Water Law impose minimum values of flow : 5% to 10% of mean annual flow in 2014 for all dams and
weirs
Locally, for each dams or weirs, the value of minimum flow can be increased based on study using microhabitat methodology.
Conclusions
Modifications of flow regime are very important in France for a large part of water bodies.
A focus was made on hydroelectricity use with : an evaluation at large scale for hydropeaking effects
on flow regime, the definition of mitigation measures at small scale
No direct relationships were established with biological index related to ecological status assessment of water bodies.