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The Study on Countermeasures for Sedimentaionin The Wonogiri Multipurpose Dam Reservoirin The Republic of Indonesia
Workshop IV, Surakarta, January 18, 2007Master Plan on Sustainable Management of Wonogiri Reservoir
Japan International Cooperation Agency – JICAMinistry of Public Works The Republic of IndonesiaNippon Koei Co. Ltd. and Yachiyo Engineering Co. Ltd.
Page / 6
SCALE
0 15 30 45 60 75 90 km
N
BENGAWAN SOLO
Flushing
Present Sediment Present Sediment Discharge at Discharge at BabatBabatBarrageBarrage
Sediment Discharge Sediment Discharge from Wonogiri from Wonogiri to be to be 0.8 million 0.8 million m3/yearm3/year
22.9 million 22.9 million m3/yearm3/year
Increase of sediment Increase of sediment discharge to Solo River discharge to Solo River estuary will be approx. estuary will be approx. 5%5% SCALE
0 15 30 45 60 75 90 km
N
BENGAWAN SOLO
Monitoring in downstream reaches
Mitigation Measures of ImpactsMitigation Measures of Impacts
Q, Turbidity Allowable limit of concentration & duration shall be defined
Basic Policy“To minimize theImpact to the d/s”by careful gate operation
(Ex.) Operation Rule
Operable period shall be strictly prohibited in dry season
Combined operation between WonogiriDam and Colo Weir
Thank You very muchThank You very muchfor Your Kind Attention !for Your Kind Attention !
Estimating sediment volume into Brantas River
after eruption of Kelud volcano on 1990
Mr. Takeshi Shimizu
National Institute for Land and Infrastructure
Management
IEstimating Sediment volume into Brantas River after eruption of Kelud Voncano on 1990
Takeshi SHIMIZU1, Nobutomo OSANAI1 and Hideyuki ITOU1 1National Institute for Land and Infrastructure Management, Ministry of Land, Infrastructure
and Transport, Japan
The Brantas River that flows through East Java Province, the Republic of Indonesia, is the second largest river. It has 11,800km2 catchment areas and total length of the river approximately 320km. The Brantas River Basin has been developed based on the 1st to 4th master plans since the Second World War. The purpose of master plans was mainly dam constructions in the middle stream and upstream for flood control, water supply for agricultural and industrial use, and electricity generation. The each plan was almost successfully completed.
In the Brantas River Basin, several active volcanoes located, originally sediment production is intense. The Brantas River Basin now has two serious water and sediment related problems as followed as bellows.
(a) The decrease of reservoir’s effective capacity due to sediment inflow to the reservoirs in the middle stream and upstream.
(b) The riverbed degradation due to sand mining in the lower stream. Related to the decrease of reservoir’s effective capacity, a total annual average
3 million m3 of sediment has flowed into reservoirs, and already filled approximately 43% of the reservoirs in 2003.
The riverbed degradation has increased the risk of damage such as the flood disasters, lateral erosion, and constructions flow out. The main factor of the riverbed degradation is considered sand mining. More than 4 million m3 of sediment were excavated from the river bed in 2000.
Moreover, volcanic materials supply due to the eruption sometimes gives additional effect along the basin. Especially Kelud volcano (elevation: 1,731m) indicates high activity; it might give serious effects to the basin.
The aim of this study is to estimating the sediment volume into Brantas River Basin after Kelud volcano eruption on 1990 using numerical simulation.
Keywords: Water and Sediment Management, Brantas river, volcanic eruption
1
Estimating sediment volume into Brantas River after eruption of Kelud volcano on 1990
SHIMIZU Takeshi, OSANAI Nobutomo and KOGA Shozo
Erosion and Sediment Control Division,Nation Institute for Land and Infrastructure Management
The 2nd International Workshop on Water and Sediment Management Malang, Indonesia
22-23 November, 2007,
Investigation Area
> Brantas River(basin area : 11,800 km2, river length : 320 km ) is located on the Island of Java, Indonesia.
>There are active volcanoes such as Kelud.
> Development plan of the Brantas river basin have started since 1959. A lot of water facilities including reservoirs were constructed in the projects.
Kelud Volcano
Surabaya
Kelut Volcano
Location map of investigation area
History of development in Brantas River Basin K
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There are 4 master plan executed in the Brantas River Basin
> Time going, economic factors increasing
> The master plans were effective. But another problem occurs
> For example sedimentation in dam reservoirs and river bed degradation
Background of this study
Eruption of Kelud volcano is thought to be one of the biggest factors to makeing serious effect on both problems
Problem 1Problem 1Riverbed degradation
caused by sand mining
Problem 2Problem 2Dam sedimentation
For the water resources management in the Brantas river basin, it is important to clarify the effect of volcano-crust for the river.
The purpose of this study
� To clarify the effect of Volcanic activities on sediment conditions in Brantas Rivers
� Authors carried out numerical analysis applied to Kelut volcano eruption on 1990.
Volcanic Activities of Kelud Volcano> Kelud volcano ( 1,731m height ) is one of the high level active volcano located in Java Island.
> It has 4 eruptions records since 1919.
> Almost all of the scale of eruptions were VEI 3
> In each event, following phenomenon also occurred:
1) Lahar due to Phreatic explosion.
2) Plinian with pylocrastic flow
3) Lahar due to the breach of crater lake
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Table : scale of eruption of Mt. Kelud since 1919.
2
The latest eruption of active volcano ,Kelud
Jawa Pos , 5th of Nov. 2007
Jawa Pos , 21st of Nov. 2007
Numerical simulation carried out in this study
Considering the types of Kelud volcano eruption,we carried out following simulations to Kelut volcano eruption on 1990.
> Lahar due to crater wall collapsed type simulaiton(2-D analysis)8> Pyroclastic flow simiulation( 2-D analysis)8> Pumice fall distribution calculation(1-D analysis)8
This calculation assumes that crater wall collapse triggering lahars.
Red relief map around crater of Kelut volcano
Simulation model for lahar Input of Hydrograph
Relationship between time and discharge
Time(s)8
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Total discharge of Water is about 4,000,000 m3
Sediment supplied by M.P.M formula
We calculate the hydrograph according to the volume of crater lake on 1990 eruption.
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Distribution of depth of the flow
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Distribution of sediment depth after lahar flow down
This figure shows sediment volume inflows into Brantas River within about 3 hours.
So the more time going, the more volume flows into Brantas River.
According to these figures, almost all of water and sediment from crater lake flows into Brantas River Basin. Total volume of water is about 4 million m3 in this case.
So, Lahar has serious effect on the conditions of Brantas River.
Simulation model for pyroclastic flow
We followed Yamashita & Miyamoto(1991)’s model in which the main body behavior is treated as the dry particle flow. Schematic model of a pyroclastic flow
Pyroclastic flow divided to two layers; Surge and main body.
Main body is dragged to surge. So, it is important to know the behavior of main body.
Result of calculation of pyroclastic flow
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Distribution of arrival time of pyroclastic flow
This results show Pyroclastic flow doesn't have serious effect on Brantas River in short term.
But pyroclastic flow supplies hillside area with a lot of unstable sediments.
So, In the long term, it becomes high potential to make debris flow or lahar generate as the secondary disasters.
Numerical analysis model of pumice fall distribution
Schematic model of volcanic plume
It is difficult to model behavior of pumice fall precisely, because pumice fall has complex factors to simulate.
We use the geometrical model following Miyamoto(1993).
Distribution of pumice fall is calculated by hight of plumes and wind direction.
4
Result of calculation of pumice fall distribution
10 cm
5 cm
Distribution of pumice fall is determined by wind direction. In Brantas River Basin, everywhere is possible to damage by pumice fall.
A lot of pumice fall does not directly fall in the Brantas River.
But After the heavy rainfall, pumice fall is possible to flow down, changing forms to concentrated flow.
Because gradient of hillside over a wide range on Kelud volcano is greater than 2 degree.
Distribution of gradient more than 2 degree about Kelud volcano
Summary and conclusion�Lahar reach the main river course. Lahar is possible to make severe impact on the sediment conditions in Brantas river basin.
�Pyroclastic flow does not reach the main course. However unstable sediment on the mountain slope is increased, so that the sediment yield will be increased.
�Pumice fall reach the main river course. But in short term the effect on changing sediment condition in Brantas River Basin is not so large.But pumice fall yields unstable sediments in Brantas River Basin.
Summary and conclusion
�We can recognize the impact of eruptions on the river is not so big in short term.
�But it is considered the potential of sediment movement is increased after eruptions.
�Because these sediment is easy to move if heavy rain falls.
Future studies of our plan
How much volume of sediment from upper reach is necessary for lower reach to become equilibrium river bed condition?
River bed degradation by sand mining
?
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We have plans to execute simulation of the river bed variation;case 1) in normal condition.case 2) in volcanic activities took place.
-> results of this presentation is preliminary studies for case 2)
Lower ReachLower ReachUpper ReachUpper Reach
After the execution of the previous simulation, We estimate how much volume of sediment is necessary for lower reach.
Then we can consider how much volume is allowed to flow down into dam reservoirs from upper reach.
5
Thank you!Terima kasih!
A Bed-Porosity Variation Model
- as a tool for integrated sediment management-
Prof. Masaharu Fujita
DPRI, Kyoto University
A Bed-Porosity Variation Model - As a tool for integrated sediment management -
Masaharu FUJITA1, Muhammad Sulaiman2 and Daizo Tsutsumi1 1Disaster Prevention Research Institute, Kyoto University
2Graduate School of Engineering, Kyoto University
Keywords: bed variation, porosity, grain size distribution, sediment management, Talbot distribution,
As the void of bed material plays an important role in fluvial geomorphology, infiltration system in riverbeds and river ecosystem, a structural change of the void with bed variation is one of the concerned issues in river management as well as bed variation. Thus, a bed-porosity variation model is strongly required and it is expected that such a model contributes the analysis of those problems as a tool for integrated sediment management.
A flow chart of the presented numerical simulation of bed and porosity variation is shown in Fig.1. As the porosity is one of the variables in this model, we must solve the following equation as a continuity equation of sediment.
011 ���
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dzt
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Fig. 1 Flow chart of the presented bed-porosity variation model
Input data
Geometric parameters of grain size distribution
Estimation of the porosity
Flow analysis
Bed variation analysis
Temporal analysis of change of grain size distribution and
porosity
Identification of grain size distribution type
Analysis of change of grain size distribution and porosity
where � = porosity of bed material, z = bed level, zo = a reference level, Qs = sediment discharge and B=channel width.
Porosity is dependent on the grain size distribution of bed material and its compaction degree. In this paper, the compaction degree is considered empirically and the porosity is assumed to be a function of geometric parameters of grain size distribution.
,.......,, 321 ���� nf� (2)
where �1,��2, �3….= geometric parameters of grain size distribution.
As we assume that the porosity is not constant depending only on the grain size distribution, the time differential term on porosity can not be neglected in Eq.(1). According to the previous exchange model between bed material and transported sediment such as Hirano’s model, the change of grain size distribution in a time interval cannot be obtained without the change in bed elevation in the time interval. This means that Eq.(1) is an explicit equation. For this problem, we obtain temporally the change in the grain size distribution in the original mixing layer and then calculate the change in bed elevation using the temporal grain size distribution as shown in Fig.1.
There are some types of grain size distribution such as lognormal distribution and Talbot distribution. Therefore, we need a method for identifying the distribution type and obtaining the relation between the geometric parameters and the porosity for each type. For example, lognormal distribution has a parameter of �����and Talbot distribution has two parameters of ���dmax/dmin, ���nt, where �=standard deviation of lnd, dmax=maximum grain size, dmin=minimum grain size and nt=Talbot number.�
A type of grain size distribution can be identified visually by the shape of grain size distribution and the probability density distribution. However, this visual identification method is not available for riverbed variation models. Thus, Sulaiman et al. (2007a) have introduced the geometric indices � and �� to identify the distribution type. The indices � and ���are defined as Eq.(3) and Eq.(4) respectively, designating the relative locations of the grain size dpeak for the peak probability density and the median grain size d50 between the minimum size dmin and the maximum size dmax.
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and lognormal region
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Fig. 3 Comparison between the measured porosity
and the simulated one for lognormal distribution
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Fig.4 Comparison between the measured porosity and the simulated one for Talbot distribution
The indices of Talbot and anti-Talbot distributions are on Line-1 (�=0 and 0<�<0.5) and Line-2 (�=1.0 and 0.5<�<1.0) in Fig.2. The indices of lognormal distribution are plotted just on the center point (0.5, 0.5). The indices of the other distribution are plotted on the area of 0<�<1 and 0<�<1, apart from Line-1, Line-2 and the center point. However, there is an area where no unimodal distribution exists. From a geometric analysis, an area where unimodal distribution exists is surrounded by Border-1, Border-2, �=0 and �=1.0 as shown in Fig.2.
It seems reasonable that the grain size distribution type is identified with the distance to the point (�, �) from Line-1, Line-2 or the center point. According to this criterion, the border line between Talbot distribution and lognormal distribution (Border-3) is written as Eq.(5) and the border line between anti-Talbot and lognormal distribution (Border-4) is expressed as Eq.(6). Fig.2 shows the domain for lognormal, Talbot and anti-Talbot distributions.
Border-3: 25.0)5.0( 2 ��� �� � (5) Border-4: 75.0)5.0( 2 ���� �� (6)
The porosity of various kind of grain size distribution can be obtained by means of a packing simulation model and an experimental method. As a result, the relation between the geometric parameter and the porosity is obtained as shown in Fig.3 and Fig.4 for lognormal distribution and Talbot distribution, respectively. The presented bed-porosity variation model was applied to the bed variation on a channel with a length of 15m and a width of 0.5m. The initial channel slope is 0.01. The end of the channel is fixed. The initial bed material has a lognormal type of grain size distribution ranging from 0.1mm to 10mm. The water is supplied at a rate of 0.02m3/s and no sediment is supplied. Under this condition, the maximum grain
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Fig.5 Simulation result on bed and porosity variation
could not be transported. Fig.5 (a), (b), (c) and (d) show the bed variation, the time and longitudinal variations of the mean grain size of surface layer and the porosity and the change in grain size distribution type. No sediment supply causes the bed degradation and the increase in porosity and mean grain size of the surface layer. Finally, the bed material had a Talbot type of grain size distribution.
The validity of this model has not been verified yet, but it is believed that this model has a good performance for the analysis of bed and porosity variation. It could be applied for the problems on bed variation and ecosystem in the downstream of dam.
References [1] Sulaiman, M., Tsutsumi, D., and Fujita, M. (2007a): Porosity of Sediment
Mixtures with Different Type of Grain Size Distribution, Annual Journal of Hydraulic Engineering, JSCE, Vol.51, pp. 133-138.
[2] Tsutsumi, D., Fujita, M., and Sulaiman, M. (2006): Changes in the void ratio and void structure of riverbed material with particle size distribution. River, Coastal and Estuarine Morphodynamics, Vol. 2, Parker, G., Garcia, M.H., eds., Taylor & Francis, pp. 1059-1065.
A A BBeded--PPorosity orosity VVariation ariation MModelodel-- as a tool for integrated sediment managementas a tool for integrated sediment management--
Dr. Masaharu FujitaDr. Masaharu FujitaMr. Muhammad SulaimanMr. Muhammad SulaimanDr. Daizo TsutsumiDr. Daizo Tsutsumi
DPRI, Kyoto UniversityDPRI, Kyoto University
BackgroundBackgroundTargets of sediment management
• Disaster prevention• Reduction of bad influence of sediment on rivers • Effective utilization of sediment resources• Environment conservation
Tools• Software …… bed variation models• Hardware ….. sabo dams, sediment flush gates,
sediment bypass tunnel
� Ecological aspects• Habitat conservation• Disturbance to riverbeds• Void of bed material
Before flushing
Just after flushing 1 year after flushing
Reservoir sedimentation managementReservoir sedimentation management
Impact of sediment flushing from Dashidaira dam and Unazuki dam ��Uki ishi situationUki ishi situation
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Spaces among particlesSpaces among particlesHabitatHabitat
A bed variation model providing the information A bed variation model providing the information on the changes in on the changes in porosityporosity and and grain size grain size distribution typedistribution type of bed materialof bed material
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T4 T3 T2 T1
C1
C2
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D1
D2
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M2
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N1
N2
N3
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20
40
60
80
100
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Perc
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N2
N3
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B3
B2
0
20
40
60
80
100
0.01 0.1 1 10 100 1000d (mm)
Perc
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nT=0.2
nT=0.4
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40
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N2
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B3
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20
40
60
80
100
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Border-1
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Border-3
Border-4
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T4 T3 T2 T1
C1
C2
C3
D1
D2
D3
M1
M2
M3
N1
N2
N3
B1
B3
B2
0
20
40
60
80
100
0.01 0.1 1 10 100 1000d (mm)
Perc
ent f
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(%)
P1Q2Q1 P2
0
20
40
60
80
100
0.1 1 10 100 100d (mm)
Perc
ent f
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(%)
H-1H-2H-3H-4H-5H-6
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
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O3
O1
F1 F3 F2 A5
A1
H4
H1
H3 A2
A3 A4 H5
0
20
40
60
80
100
0.1 1 10 100 1000d (mm)
Perc
ent f
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(%)
A-1A-2A-3A-4A-5A-6
0
20
40
60
80
100
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ent f
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(%)
O-1O-2O-3F-1F-2F-3
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Porosity and geometric parameterPorosity and geometric parameter
0.1
0.2
0.3
0.4
-0.1 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Standard deviation � L
Poro
sity
Measured
Simulated (Tsutsumi et al, 2006)
Lognormal distribution
Porosity and geometric parameterPorosity and geometric parameter
0.0
0.1
0.2
0.3
0.4
0 2 4 6 8 10 12n T
Poro
sity
measured : dmax/dmin=1129measured : dmax/dmin=201measured : dmax/dmin=53simulated : dmax/dmin=10 (Sulaiman et.al., 2007)simulated: dmax/dmin=100 (Sulaiman, et.al., 2007)
Talbot distribution
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9.9
10.0
0 5 10 15
Sediment supply
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Bed
leve
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)
Disatance (m)
Flow
9.8
9.9
10.0
0 5 10 15
Nosediment supply
0 min 30 min 60 min240 min600 min
Bed
leve
l (m
)
Disatance (m)
Flow
Case 1
Case 2
Bed variation
0
20
40
60
80
100
0.001 0.01
No sediment supply
0 min 30 min 60 min240 min600 min
Perc
ent f
iner
(%)
d (m)
x=10m
0
20
40
60
80
100
0.001 0.01
Sediment supply
0 min 30 min 60 min240 min600 min
Perc
ent f
iner
(%)
d (m)
x=10m
Case 1
Case 2
Grain size distribution of surface layer
Talbot to lognormal
Lognormal to Talbot
- / �- �/
0
5
10
60
240
TalbotLognormal
Tim
e (m
in)
Disatance (m)
Flow
0 5 10 15
0
30
60
240
600
Lognormal Talbot
Tim
e (m
in)
Disatance (m)
Flow
Case 1
Case 2
Grain size distribution type
0.2
0.3
0.4
0 5 10 15
No sediment supply
0 min 30 min 60 min240 min600 min
Poro
sity
Disatance (m)
Flow
0.2
0.3
0.4
0 5 10 15
Sediment supply
0 min 30 min 60 min240 min600 min
�
Poro
sity
Disatance (m)
Flow
Case 1
Case 2
Porosity of surface layer
0
20
40
60
80
100
0.001 0.01
Sediment supply
0 min 30 min 60 min240 min600 min
Perc
ent f
iner
(%)
d (m)
x=10m
0
20
40
60
80
100
0.001 0.01
No sediment supply
0 min 30 min 60 min240 min600 min
Perc
ent f
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(%)
d (m)
x=10m
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-0.01
0
0.01
0.02
0.03
0.04
0.05
0.06
0 5 10 15
No sediment supply
0 min 5 min 10 min
30 min 60 min120 min
Dep
ositi
on d
epth
(m)
Disatance (m)
Flow
-0.01
0
0.01
0.02
0.03
0.04
0.05
0.06
0 5 10 15
Sediment supply
0 min 30 min120 min
240 min360 min
Dep
ositi
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epth
(m)
Disatance (m)
Flow Case 3
Case 4
Deposition depth
-0.02
0
0.02
0.04
0.06
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ositi
on d
epth
(m)
Distance (m)
Deposition depth
0
0.2
0.4
0.6
0.8
1
0 5 10 15
No sediment supply
0 min 5 min 10 min
30 min 60 min120 min
Rat
io o
f fin
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dim
ent
Disatance (m)
Flow
0
0.2
0.4
0.6
0.8
1
0 5 10 15
Sediment supply
0 min10 min30 min
60 min120 min240 min
Disatance (m)
Rat
io o
f fin
er se
dim
ent
Flow Case 3
Case 4
Ratio of finer particle
0
0.1
0.2
0.3
0.4
0.5
0 5 10 15
Sediment Supply 0 min10 min30 min
60 min120 min240 min
Disatance (m)
Poro
sity
Flow
0
0.1
0.2
0.3
0.4
0.5
0 5 10 15
No sediment supply 0 min 5 min 10 min
30 min 60 min120 min
Poro
sity
Disatance (m)
Flow
Case 3
Case 4
Porosity of surface layer
0 0.2 0.4 0.6 0.8 1
0
2
4
6
8
10
No sediment supplyx=14.5mx= 5.0m
Ratio of finer sediment
Lay
er N
o.
T=120min
0 0.2 0.4 0.6 0.8 1
0
2
4
6
8
10
Sediment supplyx=14.5mx= 5.0m
Ratio of finer sediment
Lay
er N
o.
T=360min
0 0.1 0.2 0.3 0.4 0.5
0
2
4
6
8
10
No sediment supplyx= 14.5mx= 5.0m
Porosity
Lay
er N
o.
T=120min
0 0.1 0.2 0.3 0.4 0.5
0
2
4
6
8
10
x=14.5mx= 5.0m
Sediment supply
Lay
er N
o.
Porosity
T=360min
Case 3
Case 4
Vertical distribution of ratio of finer particle and
porosity
ConclusionsConclusions
Identification method forIdentification method for grain size distribution grain size distribution typetypeThe relation between the geometric parameter The relation between the geometric parameter of grain size distribution and the porosityof grain size distribution and the porosityDevelopment of a bedDevelopment of a bed--void variation modelvoid variation model
Reservoir Sediment Management Measures in Japan
and those appropriate selection strategy
Dr. Tetsuya Sumi
Kyoto University
Reservoir Sediment Management Measures in Japan and those appropriate selection strategy
TETSUYA SUMI1 1 Associate Professor, Department of Civil and Earth Resources Engineering,
Graduate School of Engineering, Kyoto University
The Japanese rivers are characterized by high sediment yield due to the topographical, geological and hydrological conditions. This has consequently caused sedimentation problems to many reservoirs constructed for water resource development or flood control purposes. The necessity for the reservoir sediment management in Japan can be summarized in the following three points: 1) to prevent the siltation of intake facilities and aggradations of upstream river bed in order to secure the safety of dam and river channel, 2) to maintain the storage function of reservoirs, and realize sustainable water resources management for the next generation, and 3) to release sediment from dams with an aim to conduct comprehensive sediment management in a sediment routing system. Sediment management approaches are largely classified into the following techniques: 1) to reduce sediment transported into reservoirs, 2) to bypass inflowing sediment and 3) to remove sediment accumulated in reservoirs. In Japan, in addition to conventional techniques such as excavation or dredging, sediment flushing and sediment bypass techniques are adopted at some dams: e.g. at Unazuki and Dashidaira dams in the Kurobe river, and at Miwa dam in the Tenryu river and Asahi dam in the Shingu river as shown in Figure 1, respectively. These dams practically using such techniques are focused on as advanced cases aiming for long life of dams. In addition to these dams, larger scale sediment bypass systems are now under studying at Sakuma and Akiba dams in the Tenryu river, and Yahagi dam. The problems to promote such reservoir sediment management in future are 1)Priority evaluation of reservoirs where sediment management should be introduced, 2)Appropriate selection of reservoir sediment management strategies and 3)Development of efficient and environmental compatible sediment management technique. In order to decide priority and appropriate sediment management measures, Capacity-inflow ratio and Reservoir life indices are useful for guidance as shown in Figure 2. When the sediment management measures are selected, it is also necessary to consider those environmental influences in the downstream river and coastal areas both from positive and negative point of views. � In this paper, state of the art of reservoir sediment management measures in Japan and future challenges are discussed.
Keywords: Reservoir sediment management, sediment routing system, sediment bypassing, sediment flushing, environmental impact assessment, Tenryu river, Yahagi river
Classification Place
Upstreamreservoirs
End ofreservoirs
Sediment checkdam
End ofreservoirs Sediment bypass
Sediment routing Sedimentsluicing
Sedimentmanagement
Insidereservoirs
Density currentventing
Drawdownflushing Sediment flushing outlet
Sediment flushing Insidereservoirs
Partial flushingwithoutdrawdown
Sediment scoring gate
Sediment scoring pipe
Excavating &Dreging
Regulation of reservoirs and sediment by erosion control damsand slit dams
Reduction of sediment production by hillside and valley works
Details of sediment control measures Examples in Japan
Sabo area, Changing from sediment check dams tosediment control dams (slit dams)
Reducing sedimentflowing intoreservoirs
Regurally excavating and recycling foraggregate or sediment supply todownstream river
Reduction of discharged sediment and river course stabilizationby channel works
Miwa Dam, Koshibu Dam, Nagashima Dam,Matsukawa Dam, Yokoyama Dam
Asahi Dam, Miwa Dam, Koshibu Dam, MatsukawaDam, Yokoyama Dam
Sabaishigawa DamDashidaira Dam-Unazuki Dam(Coordinated sluicing.
Masudagawa DamNon-gate botom outlets(natural flushing.
Botom outlets for flood control
Non-gate conduits with curtain wall
Koshibu Dam, Futase Dam, Kigawa Dam
Katagiri Dam
Selective withdrawal works Yahagi Dam
Ikawa Dam
Recycling for concrete aggregate Miwa Dam, Koshibu Dam, Sakuma Dam, Hiraoka Dam,Yasuoka Dam
Dashidaira Dam-Unazuki Dam(Coordinated flushing.
Senzu Dam, Yasuoka Dam
Soil improving material, Farm Landfilling, Banking material
Miwa Dam, Yanase Dam
Sediment replacing inside reservoir
Sediment supplying to downstream rive Akiba Dam, Futase Dam, Miharu Dam, NagayasuguchiDam, Nagashima Dam
Sakuma Dam
Figure 1. Classification of Reservoir Sedimentation management in Japan
Figure 2. Appropriate selection of reservoir sediment management strategy
References
[1] T. Sumi, Baiyinbaoligao and S. Morita, 10th International Symposium on River Sedimentation, Moscow, CD-ROM, (2007).
[2] T. Sumi and H. Kanazawa, 22nd International Congress on Large Dams, Barcelona, Q.85-R.16, (2006).
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1
Reservoir Sediment Management Measures Reservoir Sediment Management Measures in Japan and those appropriate selection strategyin Japan and those appropriate selection strategy
Kyoto University Kyoto University Tetsuya SUMITetsuya SUMI
Contents of presentationContents of presentation
•• Reservoir sedimentation in JapanReservoir sedimentation in Japan•• Reservoir sediment management Reservoir sediment management
measures in Japanmeasures in Japan•• Sediment bypassingSediment bypassing•• Sediment flushing and environmental Sediment flushing and environmental
issuesissues•• Promotion strategy of reservoir sediment Promotion strategy of reservoir sediment
managementmanagement•• ConclusionsConclusions
12"34546m3/km2/yr
Reservoir Reservoir sedimentation sedimentation in Japanin Japan
Itoigawa-Shizuoka Tectonic Line
Median Tectonic Line
In 922 dams of 18 billion mIn 922 dams of 18 billion m3 3 volume,volume,
VV total sedimentation 7.4%total sedimentation 7.4%
annual loss 0.24%/yrannual loss 0.24%/yr
•• National Inventory of reservoir sedimentationNational Inventory of reservoir sedimentation2730 dams (>15m high) with 23 billion m2730 dams (>15m high) with 23 billion m33 capacity.capacity.
Sedimentation progress of all reservoirs over 1 million mSedimentation progress of all reservoirs over 1 million m3 3
have been reported annually to the government from 1980s.have been reported annually to the government from 1980s.
Sediment yield Sediment yield potential map potential map of Japanof Japan
Total sedimentation lossesTotal sedimentation losses
–– Some Some hydroelectric damshydroelectric dams constructed before World War II more than constructed before World War II more than 50 years50 years oldold KK 60 to 80 %60 to 80 %, but problems are depend on the cases. , but problems are depend on the cases.
–– Many cases from 1950 and 1960 through the high economic growth Many cases from 1950 and 1960 through the high economic growth period more than period more than 30 years old30 years old KK beyond 40 %. beyond 40 %.
–– From 1960s, large numbers of From 1960s, large numbers of multimulti--purpose damspurpose dams KK 10 to 30 % 10 to 30 % Maintaining effective storage capacity is critical for flood conMaintaining effective storage capacity is critical for flood controltrol
and water supply.and water supply.
Total average sedimentation rate 7.4% (1.35 /18.3 billion m3)Total average sedimentation rate 7.4% (1.35 /18.3 billion m3)
K
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Need for reservoir sedimentation managementNeed for reservoir sedimentation management3 points3 points
�� Safety Management for Dams and RiversSafety Management for Dams and Rivers
To prevent the siltation of intake and other hydraulic To prevent the siltation of intake and other hydraulic facilities and aggradations of upstream riversfacilities and aggradations of upstream rivers
�� Sustainability of Water Storage VolumeSustainability of Water Storage Volume
�� Comprehensive Management of Sediment Routing Comprehensive Management of Sediment Routing System in a River Basin and Connected Shoreline System in a River Basin and Connected Shoreline ScaleScale
To prevent riverbed degradation, river morphology change To prevent riverbed degradation, river morphology change and coastal erosion caused by shortage of necessary and coastal erosion caused by shortage of necessary sediment supply from upstream including damssediment supply from upstream including dams
Comprehensive Management of Sediment Routing System Comprehensive Management of Sediment Routing System in a River Basin and Connected Shoreline Scalein a River Basin and Connected Shoreline Scale
Check dam
Storage reservoir
Riverbed degradation
Coastal erosion
Balancing of sediment transport from the source of the river to the coast
River environment change
Sedimentation
Lack of sediment supply
Sediment flow monitoring
Bed load Suspended load Wash load
2
Akibadam(1958,35MCM)
Sakuma dam(1956,327MCM)
Yasuoka dam(1936,11MCM)
Hiraoka dam(1951,43MCM)
Miwa dam(1959,30MCM)
Koshibu dam(1969,58MCM)
TenryuTenryu River, River, A=5,090kmA=5,090km22
TenryuTenryu River River MouthMouth
1946
1961
2001
Yasuoka dam (1936)
Hiraoka dam (1951)
Sakuma dam (1956)
Akiba dam (1958)
Miwa dam (1959)
Koshibu dam (1969)
Sediment Sediment suppysuppy
DicreaseDicrease
Reservoir sedimentation in Sakuma damReservoir sedimentation in Sakuma dam
JJ--Power (EPDC)Power (EPDC)19561956 Power generationPower generationGravity concreteGravity concrete Height=155.5 mHeight=155.5 m
Future estimation of reservoir Future estimation of reservoir sedimentation in Sakuma dam sedimentation in Sakuma dam
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Akiba dam
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"Sluicing WFlushing
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HSRS: Hydro-suction Sediment Removal System
Sediment Transport: Transport sediment in reservoir by dredging or other methods
Sakuma dam
Akiba dam
Reservoir sediment management measures in JapanReservoir sediment management measures in Japan
Sediment bypass tunnel
Dredging
Sediment scoring gate
Sediment check dam
Diversion weir
Afforestation
Sediment supply
Excavating
Trucking
Density current ventingMy��
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Sediment Routing
Reducing Sediment Inflow
Sediment Removal
3
Reservoir sediment management measures in JapanReservoir sediment management measures in Japan
Sediment bypass tunnel
Dredging
Sediment scoring gate
Sediment check dam
Diversion weir
Afforestation
Sediment supply
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Density current ventingMy��
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Reducing Sediment Inflow
Sediment Removal
Unazuki dam
Dashidaira dam
Miwa dam
Koshibu dam
Asahi dam
Typical sediment management Typical sediment management dams in Japandams in Japan
Flushing
Bypassing
Nunobiki dam Bypassing
Sakuma and Akiba dams
Yahagi dam
New project
Matsukawa dam
Sediment bypassing dams in the Sediment bypassing dams in the worldworld
No Name of Dam Country Tunnel Completion
Tunnel Shape
Tunnel Cross Section (B×H(m).
Tunnel Length (m)
General Slope (%)
Design Discharge (m3/s.
Design Velocity (m/s)
Operation Frequency
1 Nunobiki Japan 1908 Hood 2.9×2.9 258 1.3 39 - -
2 Asahi Japan 1998 Hood 3.8×3.8 2,350 2.9 140 11.4 13 times/yr
3 Miwa Japan 2004 Horseshoe 2r = 7.8 4,300 1 300 10.8 -
4 Matsukawa Japan Under
construction Hood 5.2×5.2 1,417 4 200 15 -
5 Egshi Switzerland 1976 Circular r = 2.8 360 2.6 74 9 10days/yr
6 Palagnedra Switzerland 1974 Horseshoe 2r = 6.2 1,800 2 110 9 2U5days/yr
7 Pfaffensprung Switzerland 1922 Horseshoe A=
21.0m2 280 3 220 10U15U
200days/yr
8 Rempen Switzerland 1983 Horseshoe 3.5×3.3 450 4 80 U14 1U5days/yr
9 Runcahez Switzerland 1961 Horseshoe 3.8×4.5 572 1.4 110 9 4days/yr
(Five bypass tunnels in Switzerland by Visher et al., 1997)
Outline of Miwa damOutline of Miwa dam
Bed and suspended load 180,000 m3
Wash load 535,000m3
Wash load
1959, H=69m 1959, H=69m V=V=29.95 MCM29.95 MCMA=A=311km311km22
Miwa dam
Diversion weir (H=20.5m)
Sediment trap weir (H=15.0m)Nagoya
Tokyo
Nagano
DamDam
Tenryuriver
Sediment bypass tunnel 2005, A=50m2 L=4300m
Purpose:MultipurposeFlood controlIrrigation
Water power
Sediment bypass (Miwa dam)Sediment bypass (Miwa dam)
7.5m
L=4,300m
7.5m
Sediment Sediment check damcheck dam
Diversion weirDiversion weir
Tunnel outletTunnel outlet
Sediment check dam
Diversion weir
Bypass operation in 2006Bypass operation in 2006
Bypass discharge
4
Sediment flushing in the Sediment flushing in the KurobeKurobe RiverRiverKurobeKurobe riverriverCatchment area = 682kmCatchment area = 682km22
River length = 85kmRiver length = 85km
Unazuki dam (2001) H=97m, V= 24.7 MCMH=97m, V= 24.7 MCM
Dashidaira dam (1985) H=76.7m, V=9 MCMH=76.7m, V=9 MCM
High mountains >3000m
H=185m
Sediment flushing dams in the World Sediment flushing dams in the World
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Sediment flushing rule by the river committee:During rainy season from June to JulyTiming of natural floods exceed discharges 300m3/s
Sedimentation Sedimentation profilesprofiles
Unazuki dam
Dashidaira dam
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AF: After flushing
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20032004 AF
2004 BF
Elevation (m)
1985
2001
Sedimentation volume Sedimentation volume change in change in DashidairaDashidaira dam dam
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
'85
'86
'87
'88
'89
'90
'91
'92
'93
'94
'95.
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'95.
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'95.
11 '96
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'98
'99
'00
'01
'02
'03
P 460e103 m3
V 80e103 m3
a 20e103 m3
S 1720e103 m3
d 800e103 m3
c 460e103 m3
_ 340e103 m3
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g 590e103 m3
h 60e103 m3
i 90e103 m3
Sedi
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Gross storage: 9e106m3
The biggest flood in 1995
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0
1000
2000
3000
4000
5000
6000
7000
8000
9000
'85
'86
'87
'88
'89
'90
'91
'92
'93
'94
'95.
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'95.
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'95.
11 '96
'97
'98
'99
'00
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'02
'03
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d 800e103 m3
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_ 340e103 m3
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g 590e103 m3
h 60e103 m3
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Sedi
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103 m
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Gross storage: 9e106m3
The biggest flood in 1995
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Degradation
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Cross section
5
�� Flushing efficiencyFlushing efficiency=scoured sediment volume / water use
�� Flushing effectFlushing effect= scoured sediment volume / total deposited
sediment volume before flushing
�� Environmental impactsEnvironmental impactsU the influences of SS rising and DO dropping -
duration time etc.
Subjects of sediment flushing
SS: Suspended solid concentration DO: Dissolved oxygen
Study on sediment discharge process during flushing operations from quantity and quality point of view is very important.
Total water use and flushed sediment volume in Total water use and flushed sediment volume in sediment flushing damssediment flushing dams
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Fe: Flushing efficiency =Total flushed sediment volume/ Total water volume
Flushing efficiency of Sediment flushing dams Flushing efficiency of Sediment flushing dams
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Environmental monitoring during sediment flushing
0 5 10 km
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Unazuki dam
Dashidaira dam
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Unazuki dam
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Shimokurobe
ReservoirReservoirWater quality(DO, SS etc.)Mud qualityCross sections
RiverRiverWater quality(DO, SS etc.)Mud qualityAquatic speciesCross sections
SeaSeaWater quality(DO, SS etc.)Mud qualityAquatic speciesCross sections
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Discharge (m3/s)
SS (mg/l)
Discharge (m3/s)
Average hourly rainfall (mm)
Water level (EL.m)
Water level (EL.m)
Sediment flushing in July 2004
Year EventFlood a a 11.3 10.5 a 3,700 1,800
Flushing 1.72MCM 8.8 9.7 8.9 103,500 29,400 26,000Flushing 0.8MCM 10.7 10.3 9.8 56,800 9,470 6,770Flushing 0.46MCM 9.8 9.2 9.3 93,200 28,900 4,330Flushing 0.34MCM 8.2 7.0 7.3 44,700 9,400 6,750
Flood a a 10.5 9.5 a 6,090 5,260Flushing 0.7MCM 6.0 5.8 6.5 161,000 52,100 25,700
Coordinatedflushing
0.59MCM 7.2 11.4 10.2 90,000 2,500 1,500
Coordinatedsluicing = 11.1 10.6 9.6 29,000 3,700 2,200
Coordinatedflushing
0.06MCM 9.5 10.5 9.5 22,000 5,400 2,800
Jun-03Coordinated
flushing 0.09MCM11.8 11.3 9.6 69,000 17,000 10,000
Jul-04 Coordinatedflushing
0.28MCM9.3 10.2 9.8 42,000 6,800 11,000
Jul-04 Flood a 10.8 11.2 10.3 30,000 12,000 14,000
Jul-04Coordinated
sluicing a 10.6 11.2 9.6 16,000 17,000 21,000
Jul-02
Unazuki
SS>mg/l?>Maximum value?
Jul-01
DO>mg/l?>Minimum value)
Dashidaira UnazukiShimo-kurobe
Jun-98Jul-98Sep-99
Jun-01
Jul-95Oct-95Jun-96Jul-97
Amount ofDashidairasedimentflushing Dashidaira
Shimo-kurobe
Sediment flushing
Measurement values of DO and SS during flushing
Manual sampling in every one hour Continuous monitoring method for DO and SS is necessaryDevelopment of new techniques for high SS monitoring
6
Balancing of Flushing efficiency and environmental Balancing of Flushing efficiency and environmental impacts impacts
Flushing efficiently = Little water
Flushing naturally = Much water
Reservoir draw downEnough flushing discharge waterRinsing discharge after flushing, etc.
Water useWater use
High sediment concentration
Low sediment concentration
Promotion strategy of reservoir sediment Promotion strategy of reservoir sediment managementmanagement
A)A) Priority evaluation of reservoirs where sediment Priority evaluation of reservoirs where sediment management should be introducedmanagement should be introduced
B)B) Appropriate selection of reservoir sediment Appropriate selection of reservoir sediment management strategymanagement strategy
C)C) Development of efficient and environmentally Development of efficient and environmentally compatible sediment management techniquescompatible sediment management techniques
A)A) Priority evaluation of reservoirs where sediment Priority evaluation of reservoirs where sediment management should be introducedmanagement should be introduced
� Reservoir sustainability factor- Reservoir life = CAP/MAS
� Comprehensive sediment management factor- impacts to the downstream
river and an actual environmental deterioration degree
� Technical difficulty factor
CAP/MAS<100yrs, 7%
CAP/MAS=100-500yrs, 34%
CAP/MAS= 500-1000yrs, 25%
CAP/MAS <1000yrs, 34%
Reservoir lives (CAP/MAS) of multipurpose dams in Japan
B)B) Appropriate selection of reservoir sediment Appropriate selection of reservoir sediment management strategymanagement strategy
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C)C) Development of efficient and environmentally Development of efficient and environmentally compatible sediment management techniquescompatible sediment management techniques
�� "Take", "Transport" and "Discharge""Take", "Transport" and "Discharge"
-- Sediment flushing/sluicing and sediment bypassing Sediment flushing/sluicing and sediment bypassing should be introduced more. should be introduced more.
-- The sediment trucking and supply, and the The sediment trucking and supply, and the HydroHydro--suction Sediment Removal System (HSRS)suction Sediment Removal System (HSRS) are are needs to be improved furthermore and introduced as needs to be improved furthermore and introduced as supplementary measures.supplementary measures.
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Sediment replenishment
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Clay, silt Mainly sand Sand and gravelSize
Water content
Ignition loss
Bed loadSuspended loadWash load
Bed load+Suspended loadWashload+Suspended load
Upstream areaMiddle area
Downstream area Delta
Bottom set bed Fore set bed Top set bed
Washload
Delta
Sedi
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Grain size content(%)
Gravel=0, Sand=10, Clay=50, Silt=40
Gravel=10, Sand=45, Clay=30, Silt=15
Gravel=30, Sand=40, Clay=20, Silt=10
Fine sediment
Small Large
Ig=over10% Ig=ca.8% Ig=ca.4%
Nutrients Small Large
Density, Porosity
w=over100% Fc=45-50% Fc=lower30% Fc=over90%
w=50-60% w=lower40%
Sediment property and recycling Sediment property and recycling
7
HSRS (HydroHSRS (Hydro--suction Sediment Removal System)suction Sediment Removal System)
�� Fixed typeFixed type-- Vortex tubeVortex tube-- Hydro pipeHydro pipe-- MultiMulti--hole suction hole suction
sediment removable sediment removable systemsystem
�� Movable typeMovable type-- Hydro JHydro J-- SY systemSY system
HYDRO PIPE
HYDRO J
SY SYSTEM
MULTI HOLE SUCTION SEDIMENT REMOVABLE SYSTEM
ConclusionConclusion�� Current status of reservoir sedimentation in Japan are ; total Current status of reservoir sedimentation in Japan are ; total
sedimentation loss is 7.4%; annual loss is 0.24%/yr.sedimentation loss is 7.4%; annual loss is 0.24%/yr.
�� Reservoir sediment management is important from the view Reservoir sediment management is important from the view points of reservoir safety, sustainability and the points of reservoir safety, sustainability and the comprehensive management of sediment routing system.comprehensive management of sediment routing system.
�� Bypassing is suitable for sediment management of existing Bypassing is suitable for sediment management of existing dams. dams.
�� Flushing is effective and Flushing is effective and ‘‘Flushing efficiencyFlushing efficiency’’, , ‘‘Flushing effectFlushing effect’’and and ‘‘Environmental impactsEnvironmental impacts’’ of sediment flushing are to be of sediment flushing are to be studied more and istudied more and it is important to cause them a balancet is important to cause them a balance. .
�� Promotion strategy of reservoir sediment management should Promotion strategy of reservoir sediment management should be established by the following points;be established by the following points;-- Priority evaluation of reservoirs where sediment management shouPriority evaluation of reservoirs where sediment management should ld
be introducedbe introduced-- Appropriate selection of reservoir sediment management strategyAppropriate selection of reservoir sediment management strategy-- Development of efficient and environmentally compatible sedimenDevelopment of efficient and environmentally compatible sediment t
management techniques.management techniques.
Thank you for your attention!Thank you for your attention!
Kurobe alluvial fan
Sediment discharge from Unazuki dam