thank you very much for your kind attention · 2009. 3. 23. · thank you very much for your kind...

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

Dis

char

ge(m

3/s)8

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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Results of lahar calculation

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

?

?

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 ��

�� x

QB

dzt

sz

oz� (1)

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.

minmax

peakmax

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50max

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Fig.2 Diagram indicating Talbot, anti-Talbot

and lognormal region

0.1

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Poro

sity

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Simulated (Tsutsumi et al, 2006)

Fig. 3 Comparison between the measured porosity

and the simulated one for lognormal distribution

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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)

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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Continuity equation of sediment

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Porosity estimation

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Particle packing simulation and measurement method

A bed variation modelA bed variation model

Flow analysisSediment transport

Bed elevation

Grain size distribution of bed material

Constant Constant porosityporosity

Water discharge

Geometric parameters

A bedA bed--porosityporosity variation modelvariation model

Flow analysisSediment transport

Bed elevation

Grain size distribution of bed material

Porosity

Water discharge

Geometric parameters

Implicit equations

Main routine and subroutineMain routine and subroutineInput data

Characteristic 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

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0.2

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Poro

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Measured

Simulated (Tsutsumi et al, 2006)

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0.0

0.1

0.2

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9.8

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)

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0 5 10 15

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leve

l (m

)

Disatance (m)

Flow

Case 1

Case 2

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0

20

40

60

80

100

0.001 0.01

No sediment supply


Perc

ent f

iner

(%)

d (m)

x=10m

0

20

40

60

80

100

0.001 0.01

Sediment supply


Perc

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(%)

d (m)

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Case 2

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10

60

240

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0

30

60

240

600

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Tim

e (m

in)

Disatance (m)

Flow

Case 1

Case 2

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0.3

0.4

0 5 10 15

No sediment supply


Poro

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Disatance (m)

Flow

0.2

0.3

0.4

0 5 10 15

Sediment supply


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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


Perc

ent f

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(%)

d (m)

x=10m

0

20

40

60

80

100

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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

on d

epth

(m)

Disatance (m)

Flow Case 3

Case 4

Deposition depth

-0.02

0

0.02

0.04

0.06

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Constant porosity (No sediment supply)Not constant porosity (No sediment supply)

Constant porosity (Sediment supply)Not constant porosity (Sediment supply)

Dep

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


Rat

io o

f fin

er se

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


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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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

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Dredging


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Sediment Removal

3

Reservoir sediment management measures in JapanReservoir sediment management measures in Japan

Sediment bypass tunnel

Dredging


Sediment check dam

Diversion weir

Afforestation

Sediment supply

Excavating

Trucking

Density current ventingMy�×�

±�åºNO

Sediment Routing

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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Flushing

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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

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Dashidaira dam

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2000

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4000

5000

6000

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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

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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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Sediment bypass, SluicingSediment flushing, Sediment scoring gate

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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Recycling infeasible

Flood discharge

Sediment replenishment

Sediment recycling for construction materials and so on

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

men

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oper

ty

Grain size content(%)

Gravel=0, Sand=10, Clay=50, Silt=40



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

thank you very much for your kind attention · 2009. 3. 23. · thank you very much for your kind...

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