High-water Level River Discharge Measurement Method in Japan
High-water Level River Discharge Measurement Method in Japan High-water Level River Discharge Measurement Method in Japan
Flood River Discharge Measurement Method in Japan Hydrologic Engineering Research Team Hydraulic Engineering Research Group Public Work Research Institute (PWRI)
- Page 2 and 3: Contents 1. Overview of River Disch
- Page 4 and 5: River Discharge Observation framewo
- Page 6 and 7: Historical back ground of Flood Dis
- Page 8 and 9: Operational Problem of Measurement
- Page 10 and 11: Technical Problem of Measurement us
- Page 12 and 13: Technical Problem of Measurement us
- Page 14 and 15: Technical Problem of Measurement us
- Page 16 and 17: Non-Contact Surface Velocity Measur
- Page 18 and 19: Assortment of Non-Contact Surface C
- Page 20 and 21: Problem of Non-Contact Surface Velo
- Page 22 and 23: Out look of Non-Contact Surface Cur
- Page 24 and 25: Problem of Pressure-type Flood Curr
- Page 26 and 27: Problem of Measurement using ADCP(b
- Page 28: Our interest • How to rating curv
Flood <strong>River</strong> <strong>Discharge</strong><br />
<strong>Measurement</strong> <strong>Method</strong> <strong>in</strong> <strong>Japan</strong><br />
Hydrologic Eng<strong>in</strong>eer<strong>in</strong>g Research Team<br />
Hydraulic Eng<strong>in</strong>eer<strong>in</strong>g Research Group<br />
Public Work Research Institute (PWRI)
Contents<br />
1. Overview of <strong>River</strong> <strong>Discharge</strong><br />
Observation <strong>in</strong> <strong>Japan</strong><br />
2. Standard Flood <strong>Discharge</strong><br />
<strong>Measurement</strong> <strong>Method</strong> <strong>in</strong> <strong>Japan</strong><br />
3. Other Flood <strong>Discharge</strong> <strong>Measurement</strong><br />
<strong>Method</strong> <strong>in</strong> <strong>Japan</strong><br />
1. Non-Contact Surface Current meter<br />
2. Pressure-flood current meter<br />
3. <strong>Measurement</strong> us<strong>in</strong>g ADCP
Feature of <strong>River</strong> <strong>in</strong> <strong>Japan</strong><br />
• Catchment area is small<br />
• <strong>River</strong>s have very steep bed<br />
slope<br />
• Annual precipitation is big<br />
<strong>Japan</strong><br />
Annual precipitation[mm/year]<br />
Other countries<br />
Most of Floods are Flash Floods<br />
<strong>in</strong> <strong>Japan</strong>
<strong>River</strong> <strong>Discharge</strong> Observation<br />
framework <strong>in</strong> <strong>Japan</strong><br />
Oversee<br />
<strong>River</strong> Bureau,MLIT<br />
PWRI<br />
Technical Support<br />
Manual Preparation<br />
Regional Bureaus<br />
Check the data ,has responsibility <strong>in</strong><br />
the data.<br />
Local Work offices<br />
Order observation<br />
Local survey company<br />
Observed data<br />
<strong>River</strong><br />
<strong>Discharge</strong><br />
Observation<br />
Flood<br />
<strong>Discharge</strong><br />
<strong>Measurement</strong><br />
Low-flow<br />
discharge<br />
<strong>Measurement</strong>
Feature of Flood <strong>River</strong> <strong>Discharge</strong><br />
<strong>Measurement</strong> <strong>in</strong> <strong>Japan</strong><br />
Problem<br />
• There are a lot of debris flows.<br />
• Current velocity is high.<br />
Contact current meter is almost impossible<br />
<strong>Measurement</strong> us<strong>in</strong>g Floats has become<br />
standard <strong>in</strong> <strong>Japan</strong>.
Historical back ground of Flood <strong>Discharge</strong><br />
<strong>Measurement</strong> <strong>in</strong> <strong>Japan</strong><br />
M<strong>in</strong>istry of construction staffs observed by themselves often<br />
us<strong>in</strong>g bamboo which grow naturally around observatory at its<br />
early period<br />
Increased observatory(about 1400<br />
place <strong>in</strong> <strong>Japan</strong> for MLIT)<br />
Decreased staffs<br />
Local construction office can’t<br />
observe discharge by itself<br />
S<strong>in</strong>ce an office cannot apply a large<br />
amount of cost, the quality of data<br />
may have fallen off.<br />
ex:<strong>Discharge</strong> and WL observatory<br />
relevant to Tone <strong>River</strong> bas<strong>in</strong> (We<br />
can see a lot of observatory )
<strong>Measurement</strong> us<strong>in</strong>g Floats<br />
• Characteristic<br />
1. Standard method of Flood <strong>River</strong> <strong>Discharge</strong><br />
<strong>Measurement</strong> to make rat<strong>in</strong>g curve<br />
2. Plunge floats from a bridge
Operational Problem of <strong>Measurement</strong><br />
us<strong>in</strong>g Floats.1<br />
• It is difficult to observe the WL rais<strong>in</strong>g time or peak time.<br />
• Decreas<strong>in</strong>g expert observers (It became impossible to contract with<br />
one contractor who have know-how for long time,because bid system<br />
was changed)<br />
The example by<br />
which the data of a<br />
rise term is not<br />
observed
Technical Problem of <strong>Measurement</strong><br />
us<strong>in</strong>g Floats.1<br />
• Now averaged (max.&m<strong>in</strong>.) conversion factor<br />
for each type of float is as follows:<br />
1) Surface float: 0.85 ( valid for h 0.7m )<br />
2) 0.5 m float: 0.88 ( valid for h = 0.7 1.3m )<br />
3) 1 m float: 0.91 ( valid for h = 1.3 2.6m )<br />
4) 2 m float: 0.94 ( valid for h = 2.6 5.2m )<br />
5) 4 m float: 0.94 ( valid for h 5.2m )<br />
This standard was decided about 40 years ago, Then, research was<br />
progressed and the problems mentioned later was po<strong>in</strong>ted out. So,we<br />
should re-check these factors.<br />
We are go<strong>in</strong>g to check these factors<br />
from this year to next year
Technical Problem of <strong>Measurement</strong> us<strong>in</strong>g<br />
Floats.2(Hypothesis on Disturbed flow <strong>in</strong> the downstream of bridge piers)<br />
Actual discharge value:Q<br />
Q<br />
<br />
<br />
Non-back flow field<br />
Back flow field<br />
<strong>Discharge</strong> observed value based on the current standard Q’<br />
Q 1 =A 1 <br />
Q 2 =A 2 V 2<br />
Non-back flow field<br />
Q 1 <strong>Discharge</strong> of non-back flow field ,A 1 river area of non-back flow field,<br />
V 1 average velocity of non-back flow field,<br />
Q 2 <strong>Discharge</strong> of back flow field,A 2 river area of back flow field,<br />
V 2 average velocity of back flow field<br />
V 1<br />
Q=Q 1 +Q 2<br />
=A 1 V 1 +A 2 V 2<br />
Q 1 =A 1 V 1<br />
Q<br />
<br />
<br />
Non-back flow field<br />
Q 1<br />
=A 1<br />
(V 1<br />
+V <br />
)<br />
Back flow field Q 2<br />
=A 2<br />
(V 1<br />
+V <br />
)<br />
Q’= Q 1<br />
+Q 2<br />
=(V 1<br />
+V <br />
)(A 1<br />
+A 2<br />
)<br />
Non-back flow field Q 1<br />
=A 1<br />
(V 1<br />
+V <br />
)<br />
Q 1 <strong>Discharge</strong> of non-back flow field,A 1 river area of non-back flow field,V 1 average velocity of non-back flow field,<br />
V acceleration by aboideau ris<strong>in</strong>g effect,Q 2 <strong>Discharge</strong> of back flow field,A 2 river area of back flow field<br />
comparison of <strong>Discharge</strong> observed value of current standard and Actual discharge observed value<br />
Q’=Q+(V 1 -V )A 2 +V (A 1 +A 2 )<br />
<strong>Discharge</strong> observed value based on the current<br />
standard has overestimates the river discharge<br />
The part become exorbitance<br />
caused bythe underl<strong>in</strong>e part<br />
Tone <strong>River</strong> downstream construction office<br />
Tone <strong>River</strong> downstream part river bed and discharge observation research report <strong>in</strong> 1999
Hypothesis on Disturbed flow <strong>in</strong> the downstream of<br />
bridge pies<br />
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vertically averaged current velocity [m/s]<br />
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It is shown that current velocity become low around the<br />
bridge piers.<br />
<br />
transverse direction distance [m]<br />
Vertically averaged current velocity observation data by<br />
ADCP (10/3/2003 at Isikariohasi observatory)
Technical Problem of <strong>Measurement</strong> us<strong>in</strong>g<br />
Floats.3<br />
(Hypothesis on parallel spiral flow)<br />
<br />
‘Parallel spiral flow’<br />
is created <strong>in</strong> the<br />
downstream of bridge<br />
basements. Floats are<br />
apt to be concentrated<br />
<strong>in</strong> the l<strong>in</strong>es. Velocity<br />
is about +10% more<br />
than the average.”<br />
Accord<strong>in</strong>g to Dr. Ryosaku<br />
KINOSHITA (1998) A<br />
discussion on the flood<br />
discharge measurement <strong>in</strong> the<br />
downstream of river, Journal of<br />
<strong>Japan</strong> Society of Hydrology &<br />
Water Resources, vol.11, No.5,<br />
pp.460-471 471 (<strong>in</strong> <strong>Japan</strong>ese).
The observation by ADCP (19/12/2000,Mashimo discharge observatory)<br />
Hypothesis of parallel spiral flow<br />
The figure which changed the depth to<br />
width <strong>in</strong>to 1 to 1<br />
:uv component Contour diagram<br />
:w component Contour diagram<br />
Upstream<br />
Downstream<br />
From upstream and downstream the periodic structure<br />
appeared regularly.<br />
we can guess the existence of a parallel spiral flow.
Technical Problem of <strong>Measurement</strong><br />
us<strong>in</strong>g Floats.4(other problem)<br />
When vegetation flourish on flood channel, floats don’t<br />
run properly<br />
• It is difficult to use floats <strong>in</strong> the middle<br />
<strong>water</strong> level or on the river terrace.<br />
Not flow floats<br />
these area
Other flood <strong>River</strong> <strong>Discharge</strong> <strong>Measurement</strong><br />
<strong>Method</strong>s<br />
In order to supplement the drawback of float observation,<br />
we need to develop and put other techniques <strong>in</strong> operational.<br />
Development of other flood <strong>River</strong> <strong>Discharge</strong><br />
<strong>Measurement</strong> <strong>Method</strong>s <strong>in</strong> <strong>Japan</strong><br />
. Non-Contact Surface Velocity <strong>Measurement</strong><br />
(supplement method for <strong>Measurement</strong> us<strong>in</strong>g floats)<br />
. Pressure-type Flood Current Meter<br />
( for <strong>in</strong>vestigation use only)<br />
. ADCP<br />
(under <strong>in</strong>vestigation for high <strong>water</strong>)
Non-Contact Surface Velocity<br />
<strong>Measurement</strong><br />
Characteristic<br />
1. Measure river surface velocity (estimate cross-sectional<br />
total discharge by summ<strong>in</strong>g up each of the cross-sectional areas.<br />
Vertically averaged velocity is calculated us<strong>in</strong>g a conversion factor )<br />
2. 4 types of Non-Contact Surface current meter<br />
were developed(The PWRI and other six private<br />
companies developed them for four years. The current<br />
meters are attached on bridge or bank of river,<br />
and we can observe automatically even from a<br />
remote office.
Assortment of Non-Contact Surface<br />
Current Meter1<br />
• Doppler type<br />
1. Radio wave-type current meter<br />
2. Ultrasonic-type current meter
Assortment of Non-Contact Surface<br />
Current Meter2<br />
• Image process<strong>in</strong>g type<br />
1. PIV current meter<br />
2. Optical Flow current meter
Problem of Non-Contact Surface<br />
Velocity <strong>Measurement</strong><br />
1. Conversion factor is subject to change<br />
We decided conversion factor from observed<br />
data at Uono-<strong>River</strong> and Tone-<strong>River</strong>,<br />
We must get more data and verify the factor<br />
us<strong>in</strong>g the data.<br />
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<strong>Discharge</strong> by Non-Contact<br />
Surface Current Meter [m3/s]<br />
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<strong>Discharge</strong> by float observation[m3/s]<br />
The <strong>Discharge</strong> by Non-contact<br />
Surface Current Meter us<strong>in</strong>g the<br />
conversion factor made from<br />
Uono-<strong>River</strong> and Tone-<strong>River</strong> data<br />
are settled <strong>in</strong> less than about 5%<br />
of float observation discharge.
Problem of Non-Contact Surface<br />
Velocity <strong>Measurement</strong><br />
1. Correction of W<strong>in</strong>d Effect.<br />
We made the algorithm to elim<strong>in</strong>ate w<strong>in</strong>d current and<br />
tested the effect <strong>in</strong> an <strong>in</strong>door experiment, but we haven’t<br />
developed method to elim<strong>in</strong>ate the effect of w<strong>in</strong>dswell.<br />
The relative error of discharge measured<br />
value[%]<br />
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Radio<br />
wave<br />
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Ultra<br />
Sonic<br />
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PIV<br />
<br />
Optical<br />
flow<br />
With no <strong>in</strong>fluence<br />
compensation of a<br />
w<strong>in</strong>d<br />
With <strong>in</strong>fluence<br />
<br />
compensation of a<br />
w<strong>in</strong>d
Problem of Non-Contact Surface<br />
Velocity <strong>Measurement</strong> 3<br />
1. Cost is expensive
Out look of Non-Contact Surface Current<br />
Meter<br />
We will get data from new 6 sites <strong>in</strong> this year
Pressure-type Flood Current Meter<br />
• Characteristics<br />
1. Used for turbulence 2D constitution research<br />
ma<strong>in</strong>ly<br />
2. hanged from a bridge<br />
3. Measure vertical <strong>water</strong> velocity profile
Problem of Pressure-type Flood<br />
Current Meter<br />
1. Cost is expensive<br />
(about ¥100,000,000$850,000)<br />
2. Possibility of miss by flow<strong>in</strong>g objects<br />
or when current velocity is fast (more<br />
4m/s)
<strong>Measurement</strong> us<strong>in</strong>g ADCP(by radiocontrolled<br />
boat)<br />
• Characteristics<br />
1. Used for turbulence 3D structure of turbulence <strong>in</strong><br />
river flow<br />
2. Measure vertical <strong>water</strong> velocity profile precisely<br />
3. We can use it if current velocity is not so fast (less<br />
than 34m/s)
Problem of <strong>Measurement</strong> us<strong>in</strong>g<br />
ADCP(by radio-controlled boat)<br />
1. Steer<strong>in</strong>g of radio-controlled boat is difficult.<br />
(Substantially only one company has the operation<br />
technology.)<br />
2. It is difficult to use if current velocity is high
Conclusion<br />
• Float observation is standard <strong>in</strong> <strong>Japan</strong><br />
• In order to supplement the drawback of float<br />
observationNon-Contact Surface Velocity<br />
<strong>Measurement</strong>, Pressure-type Flood Current<br />
Meter, <strong>Measurement</strong> us<strong>in</strong>g ADCP are now<br />
be<strong>in</strong>g developed.
Our <strong>in</strong>terest<br />
• How to rat<strong>in</strong>g curve management<br />
• The other possibility of us<strong>in</strong>g Non-Contact<br />
Surface Velocity <strong>Measurement</strong><br />
• The other possibility of us<strong>in</strong>g ADCP