flow measurements instruments and techniques n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Flow Measurements Instruments and Techniques PowerPoint Presentation
Download Presentation
Flow Measurements Instruments and Techniques

Loading in 2 Seconds...

play fullscreen
1 / 29

Flow Measurements Instruments and Techniques - PowerPoint PPT Presentation


  • 233 Views
  • Uploaded on

Flow Measurements Instruments and Techniques. Technical and metrological needs and efforts: The case of France. Ouvèze River – Vaison-la-Romaine, South-East France – 22 th September 1992. WMO – Exploratory Meeting Assessment of the Performance of Flow Measurements Instruments and Techniques.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Flow Measurements Instruments and Techniques' - farren


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
flow measurements instruments and techniques
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

slide2

Summary

  • River flow measurements in France
    • floods, rivers and uses
    • hydrometric services
    • needs for methodology and metrology
  • Assessment of the instruments and techniques performance
    • uncertainties associated with various gauging methods
    • field tests and aDcp regattas
    • rating curves: uncertainty assessment and extension
  • Research on innovating methods
    • acoustic Doppler current profilers (aDcp, Groupe Doppler)
    • discharge monitoring systems
    • projects for video-based field measurements (LS-PIV)
slide3

Flow Measurements Instruments and Techniques

  • River flow measurements in France
    • floods, rivers and uses
    • hydrometric services
    • needs for methodology and metrology
slide4

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...
slide5

Gard River, St-Nicolas Bridge, September 2002

Floods, rivers and uses in France

  • Specific technical challenges:
    • Influenced reaches (tides, shipping...)
    • Flash floods:
      • Mediterranean belt
      • French tropical islands
      • (Martinique, Guadeloupe, La Réunion…)

27 m

Borne river (Ardèche catchment)

slide6

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...

Source: MEDD/DE/SCHAPI 2006

slide7

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

slide8

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
  • 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

Source Cemagref Lyon

slide9

Flow Measurements Instruments and Techniques

  • 2. Assessment of the instruments and techniques performance
    • uncertainties associated with various gauging methods
    • field tests and aDcp regattas
    • rating curves: uncertainty assessment and extension
slide10

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)

slide11

UADCP / QADCP

UCM / QCM

Uncertainties associated with various gauging methods

  • QADCP uncertainty from comparison with current-meter (QCM ) (CNR/Cetiat, NF ENV 13005)

U = bias + k * reproducibility = 7.9 % (k=2)

UADCP = 4-6 %

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)

slide12

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)

slide13

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

slide14

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

slide15

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.

slide16

Flow Measurements Instruments and Techniques

  • 3. Research on innovating methods
    • acoustic Doppler current profilers (aDcp, Groupe Doppler)
    • discharge monitoring systems
    • projects for video-based field measurements (LS-PIV)
slide17

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

slide18

VLSPIV

Water level

Bathymetry profile

Discharge monitoring systems

  • From continuous velocity sampling to discharge time series:
  • Transit time ultrasonic systems
  • Doppler flow-meters (small streams)
  • Horizontal aDcp (H-aDcp)
  • Radar Bragg diffraction
  • Video-based velocimetry (LS-PIV)
  • Quality of velocity estimates
  • Assumptions on the velocity field structure
slide19

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)

slide20

Uncertainty u(S) in %

Water depth h [metres]

Doppler flow-meters (small streams)

Estimation of the section area uncertainty for sections with different batter slopes:

<23° (A&B) vs. 40° (C&D)

slide21

Doppler flow-meters (small streams)

Relative discharge error (%)

at 4 Doppler flow-meter stations

(against standard stream discharge measurements)

st georges h adcp cnr sa ne river lyon

Streamwise velocity

Width 75 m

24h (time step = 1 min)

St-Georges H-aDcp (CNR, Saône river, Lyon)

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)

st georges h adcp adcp dataset postprocessing
St-Georges H-aDcp: aDcp dataset postprocessing

z/h0

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)

slide24

St-Georges H-aDcp: performance evaluation

uaH-aDcp/uaDcp

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)

slide25

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.
slide26

LS-PIV : tests during a dam release (Arc 2006)

LS-PIV surface velocities & gauging transect

Artificial tracers (cornstarch chips)

10-m high mast & remotely controlled video camera

slide27

77 m3/s

113 m3/s

LS-PIV : tests during a dam release (Arc 2006)

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)