Densitometric probe based on non-differential pressure the technique allowing to follow suspended matter loads at very high concentrations Department of Water Pollution Control D. Petrovic, A. Marescaux, J-P. Vanderborght & M. A. Verbanck IT4water project
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Densitometric probe based on non-differential pressure the technique allowing to follow suspended matter loads at very high concentrations
Department of Water Pollution Control
D. Petrovic, A. Marescaux, J-P. Vanderborght & M. A. Verbanck
IT4water project
Suspended sediment monitoring: no universal technique
FIT
LISST
WTW ViSolid
Advanced optical probes
Gamma
Alpha
Nuclear probes
UHCM
aDcp
Densitune
Vibrating device
Acoustic methods Remote Sensing Densitometry
(760 - 900 nm)
Manual
Differential pressure
Rapid changes in water depth and suspended sediment concentrations (10 to 30 g/L). Surveillance bridge in
Caojiaquan, Lower Yellow River, Northern China.
Rapid changes in water depth and SSC (10 - 30 g/l) Caojiaquan, Lower Yellow River, Northern China
St Donat-sur-Herbasse, France, 6 Sep 2008
Which sensing method is available to monitor SSC at these high concentrations ?
T°
p
p0
H’
pressure sensor in air
radar limnimeter
H
pressure sensor & thermometer
Densitometric probe – based of absolute pressure measurements
Proxy method based on combination of four sensors
M. A. Verbanck, D. Petrovic & J-P. Vanderborght
International patent application N° PCT/EP2012/054135
5
rw(T) =
rw(T
0)
1+ b(T - T0)
Cv =r
w(T)
rs- r
w(T)
p- p0
rw(T)gH
-1æ
èçç
ö
ø÷÷
suspended sediment volumetric concentration
Densitometric probe – basic principles
p= rLgH
rL
= (1-Cv)rW
(T)+Cvrs
Observed suspended sediment volumetric concentration versus known suspended sediment volumetric concentration (relative error less than 9%)
Test in static conditions
2,5 m deep cylindrical tank
water level at 2 m
water temperature & atm
pressure constant
test of various sensors
Amazon river plume data: - campaign to test DensiTune instrument (acoustic characterization of sediments) - Lab "Acoustics and environmental Hydroacoustics”, ULB , June 2012 , led by Prof. Hermand
Cv =r
w(T)
rs- r
w(T)
p- p0
rw(T)gH
-Cvsalt
rsalt
- rw(T)
rw(T)
-1æ
èçç
ö
ø÷÷
Test in environment with non negligible salt presence
Densitometric probe – validation in natural environment
Ecuador – Jadan river (SSC up to 25g/l) Jan-Apr 2014 – expected rain season
Results application in complex geometry use of sensors with regular sensitivity
Difficulties: unexpected weather conditions influence of air bubbles & floatables water level measurement problems
Ecuador – Jadan river (Jan-Apr 2014 )
Densitometric probe – validation in natural environment
Densitometric probe – (potential) new test site
Laval, Draix – French Southern Alps
Monitoring since 1984
water level: before 1997: bulle-à-bulle,
US, ellan & pressure sensor presently: US &
conductivity based method
SSC – sampling + optical device
Hyperconcentrated black marly slurry 800 g/l on Aug 13, 1997
Densitometric probe concept applied on historical data at Laval maximal SSC in g/l