Transcript Diapositive 1

Flow Measurements Instruments and Techniques
Technical and metrological needs and efforts:
The case of France
Ouvèze River – Vaison-la-Romaine, South-East France – 22th September 1992
WMO – Exploratory Meeting
Assessment of the Performance of Flow Measurements
Instruments and Techniques
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Summary
1. River flow measurements in France
1. floods, rivers and uses
2. hydrometric services
3. needs for methodology and metrology
2. Assessment of the instruments and techniques performance
1. uncertainties associated with various gauging methods
2. field tests and aDcp regattas
3. rating curves: uncertainty assessment and extension
3. Research on innovating methods
1. acoustic Doppler current profilers (aDcp, Groupe Doppler)
2. discharge monitoring systems
3. projects for video-based field measurements (LS-PIV)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Flow Measurements Instruments and Techniques
1. River flow measurements in France
1. floods, rivers and uses
2. hydrometric services
3. needs for methodology and metrology
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Floods, rivers and uses in France
• Floods = the most
damaging natural
hazard in France
• River habitats:
min. flow rates and
max. water
temperature (EU
WFD 2000)
• Most of the large
rivers are
regulated
(excepted the
Allier-Loire rivers)
Lyon flooded by the Saône river in 1856
• Uses: water supply, industry, agriculture (irrigation), power generation
(hydropower, cooling of nuclear power plants), navigation, tourism...
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Floods, rivers and uses in France
Gard River, St-Nicolas
Bridge, September 2002
• Specific technical challenges:
• Influenced reaches (tides, shipping...)
• Flash floods:
• Mediterranean belt
• French tropical islands
(Martinique, Guadeloupe, La Réunion…)
Borne river (Ardèche catchment)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
27 m
The French galaxy of flow measurement
•
National hydrometric network
Regional Environment Agencies
(DIREN), Flood Forecast Services
(SPC and SCHAPI), Ministry of
Environment (MEDD), MétéoFrance
•
Hydropower industry
Electricité de France (EDF),
Compagnie Nationale du Rhône
(CNR)
•
Waterways office
Voies Navigables de France (VNF),
Ministry of Infrastructure
•
Research institutes and
laboratories
Cemagref, IRD (Brazil, Africa...),
LTHE, CEREGE, universities...
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Source:
MEDD/DE/SCHAPI 2006
The French galaxy of flow measurement
Real-Time Flood Forecast (SPC/SCHAPI/MEDD)
www.vigicrues.ecologie.gouv.fr
4 warning levels
Source: MEDD/DE/SCHAPI 2007
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Needs for methodology and metrology
• Accurate river flow measurements are requested for
• hydrological research and studies
• human uses (water supply, power plants, agriculture, …)
• river management (flood risk, habitats…)
• Technical and metrological difficulties
• field deployment conditions (floods, night…)
• rating curves: uncertainty assessment and extension
• uncertainties associated with various gauging methods
Source Cemagref Lyon
• Innovating methods bring new solutions… and new problems!
• need for standard procedures (field operations and data processing)
• comparison with classical methods (and subsidiarity)
• performance, limitations and uncertainty assessment
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Flow Measurements Instruments and Techniques
2. Assessment of the instruments and techniques performance
1. uncertainties associated with various gauging methods
2. field tests and aDcp regattas
3. rating curves: uncertainty assessment and extension
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Uncertainties associated with various gauging methods
• U(Q)=5-7% for current-meter discharges (ISO 748 & NF ENV 13005 “GUM”)
• Current-meter and aDcp gauging comparison (CNR/Cetiat)
Olivier et al. 2006, CNR/Cetiat
Estimation des incertitude sur les débits des écoulements à surface libre déterminés par jaugeage à l'ADCP ou au moulinet 13ème Congrès International de Métrologie (Lille, France)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Uncertainties associated with various gauging methods
• QADCP uncertainty from comparison with current-meter (QCM )
(CNR/Cetiat, NF ENV 13005)
(k=2)
UADCP / QADCP
U = bias + k * reproducibility = 7.9 %
UADCP = 4-6 %
UCM / QCM
Olivier et al. 2006, CNR/Cetiat
Estimation des incertitude sur les débits des écoulements à surface libre déterminés par jaugeage à l'ADCP ou au moulinet 13ème Congrès International de Métrologie (Lille, France)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Field tests and aDcp regattas
• Comparison tests performed by the different
services (EDF/CNR/MEDD…)
• Results for aDcp’s are being collected by the
Groupe Doppler
• Wide and open diffusion of the results
(Internet?)
•
Source EDF-DTG Grenoble
Need for accepted protocols and comparison standards
• suitable site (gauging requirements, logistics, safety…)
• reference discharge values and hydrodynamical conditions
• parameter configuration and deployment procedures (Ntransect = 6)
• interpretation of the results
Vignon 2006, EDF-DTG
Comparaison des mesures avec divers ADCP: Broad-Band, Rio-Grande, Streampro (rapport technique)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Rating curves: uncertainty assessment
Uncertainty assessment based on
standard NF ENV 13005 "Guide for the
expression of the Uncertainty of Measurement" (1999)
Rhône at Beaucaire
(1994-2003, 54
gauging values)
U(Q) = 8-10%
Olivier et al. 2006, CNR
Incertitude sur les débits calculés à
partir des courbes de
transformation hauteur/débit
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Rating curves: extension
•
A review of a set of 327 rating curves (Cemagref/MEDD, 2005-2006)
T < 1 yr
(53%)
1 < T < 2 yr
(7%)
2 < T < 10 yr
(31%)
10 < T < 100 yr
(8%)
T > 100 yr
(1%)
Lang et al. 2006, Cemagref
Review on the rating curves of the
national French database
(HYDRO) for flood discharge – 5th
FRIEND World Conference
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Rating curves: extension
High-discharge extension based on hydraulic modelling (1D/2D)
Hérault river at
Ganges-Laroque
Relative error :
dQ/Q=20 to 30%
Lang et al. 2006, Cemagref
Review on the rating curves of the
national French database
(HYDRO) for flood discharge
– 5th FRIEND World Conf.
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Flow Measurements Instruments and Techniques
3. Research on innovating methods
1. acoustic Doppler current profilers (aDcp, Groupe Doppler)
2. discharge monitoring systems
3. projects for video-based field measurements (LS-PIV)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
The “Groupe Doppler”
• A forum for French aDcp users
(2005, CNR/MEDD/EDF)
• Technical solutions, mobile bed!
• Metrological tests and comparisons
• aDcp methodological guide (2007?)
Photos: DIREN RA & CNR
Le Coz et al. 2007, Cemagref
Uses of aDcp in rivers: a review (in French) – La Houille Blanche
ADcp river discharge measurement: sharing experience (in French) – La Houille Blanche
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Discharge monitoring systems
From continuous velocity sampling to discharge time series:
VLSPIV
•
Transit time ultrasonic systems
•
Doppler flow-meters (small streams)
•
Horizontal aDcp (H-aDcp)
•
Radar Bragg diffraction
•
Video-based velocimetry (LS-PIV)
Water
level
Quality of velocity estimates
Assumptions on the velocity field structure
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Bathymetry
profile
Doppler flow-meters (small streams)
Birgand, Benoist et al. 2005, Cemagref
Mesure des débits à l’aide de débitmètres
ultrasoniques Doppler - Cas des petits cours
d’eau ruraux, Ingénieries – EAT, 41, 23-38
Correlation between the mean velocity
(Vm=Q/S) and the flow-meter velocity (Vc)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Uncertainty u(S) in %
Doppler flow-meters (small streams)
Water depth h [metres]
Estimation of the section area
uncertainty for sections with
different batter slopes:
<23° (A&B) vs. 40° (C&D)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Doppler flow-meters (small streams)
Relative discharge
error (%)
at 4 Doppler flowmeter stations
(against standard
stream
discharge
measurements)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
St-Georges H-aDcp (CNR, Saône river, Lyon)
Width 75 m
Streamwise velocity
Influence of downstream dam (backwater)
3 beam H-aDcp 300 kHz (TRDI)
Q computed from point velocity
measurements through a theoretical
vertical profile
Parameters : z0 and A1 (VISEA-H; Van
Rijn, 1986)
24h (time
step = 1 min)
WMO CHy – Flow Measurements – Geneva, 2007/04/25
– J. LE COZ
z/h0
St-Georges H-aDcp: aDcp dataset postprocessing
u/<uref>
Experimental unit profile ( z0 , A1 )
Surface coefficient (α=0.91±0,04)
H-aDcp vs. aDcp: DQ/Q <3%
Le Coz et al. 2007, Cemagref/CNR
Mean vertical velocity profiles from aDcp river discharge measurement
datasets – 32nd Congress of IAHR (Venice, Italy)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
uaH-aDcp/uaDcp
St-Georges H-aDcp: performance evaluation
Distance from H-aDcp [m]
Problems: far-field, low flows…
Empirical regressions (index velocity)
Metrological analysis in progress
Le Coz et al. 2007, Cemagref/CNR
Experimental evaluation of a horizontal Doppler profiler (H-aDcp) – HMEM07 (Lake Placid, USA)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Projects for video-based field measurements (LS-PIV)
• Principle of operation: tracking surface movements by image analysis
• Geometric correction of images: surface velocities from [pixels/s] to [m/s]
• Discharge computation from bathymetry profile and hydrodynamical
assumptions on the velocity field structure
• Performance assessment and potential error sources
• Non-contact discharge monitoring (flash-floods!)
• Collaboration: IIHR (Iowa City), LTHE (Grenoble) and Cemagref (Lyon)
• Iowa City LS-PIV station (IIHR, M. Muste, A. Hauet...)
• Tests in 2005-2006 (LTHE/Cemagref) : Arc river
• The Ardèche river project 2007-2008 (LTHE/Cemagref/CNR/SPC-GD)
• Other application opportunities in France: Ain river, Guadeloupe Island,
etc.
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
LS-PIV : tests during a dam release (Arc 2006)
10-m high mast &
remotely controlled video
camera
LS-PIV surface
velocities & gauging
transect
Artificial tracers
(cornstarch chips)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
LS-PIV : tests during a dam release (Arc 2006)
77 m3/s
113 m3/s
LS-PIV and
simulated
(Rubar20 code)
velocities
Q_currentmeter (blue dots)
Q_LSPIV (red dots)
Q_rating curve (solid line)
Jodeau, Hauet et al. 2007, Cemagref/LTHE/IIHR
LSPIV technique to measure surface flow velocities during a
reservoir flushing – HMEM07 (Lake Placid, USA)
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Flow Measurements Instruments and Techniques
Thanks for your attention.
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ
Flow Measurements Instruments and Techniques
WMO CHy – Flow Measurements – Geneva, 2007/04/25 – J. LE COZ