Thank You Very Much for Your Kind Attention !

The Study on Countermeasures for Sedimentaion Workshop IV, Surakarta, January 18, 2007 in The Wonogiri Multipurpose Dam Reservoir Master Plan on Sustainable Management of Wonogiri Reservoir in The Republic of Indonesia

Mitigation Measures of Impacts Present Sediment

N Discharge at Babat Basic Policy BENGAWAN SOLO Barrage (Ex.) Operation Rule “To minimize the Q, Turbidity Allowable limit of 22.9 million Impact to the d/s” m3/year concentration & m3/year by careful gate operation duration shall be defined

N Combined operation BENGAWANbetween SOLO Wonogiri Dam and Colo Weir Sediment Discharge from Wonogiri Monitoring in Increase of sediment to be 0.8 million downstream reaches m3/year discharge to Solo River Operable period SCALE estuary will be approx. shall be strictly 5%0 15 30 45 60 75 90 km SCALE prohibited in dry 5% 0 15 30 45 60 75 90 km Flushing season

Thank You very much for Your Kind Attention !

Japan International Cooperation Agency – JICA Ministry of Public Works The Republic of Indonesia Nippon Koei Co. Ltd. and Yachiyo Engineering Co. Ltd. 䋭㩷㪈㪉㪋㩷䋭 Page / 6

Estimating sediment volume into Brantas River after eruption of Kelud volcano on 1990

Mr. Takeshi Shimizu National Institute for Land and Infrastructure Management

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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

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Investigation Area

Surabaya Estimating sediment volume into > Brantas River(basin area : 11,800 km2, river length : 320 km ) is located Brantas River after eruption of on the Island of Java, Indonesia. Kelud volcano on 1990 >There are active volcanoes such as Kelud. Kelud Volcano SHIMIZU Takeshi, OSANAI Nobutomo and KOGA Shozo Kelut Volcano > Development plan of the Brantas river basin have started since 1959. A Erosion and Sediment Control Division, lot of water facilities including Nation Institute for Land and Infrastructure Management reservoirs were constructed in the projects.

The 2nd International Workshop on Water and Sediment Management Malang, Indonesia Location map of investigation area 22-23 November, 2007,

2nd 3rd 4th ፸፻፷፷፷፷ ਈϊAgriculture ፸፹፷፷፷፷ 7ϊIndustry Background of this study History of ፸፷፷፷፷፷ ᎎᎋ᎗GDP

ᮖ᭿᭍ᯙ ፿፷፷፷፷ ᎀ 1st ፽፷፷፷፷

GDP ፻፷፷፷፷ development in ɢɥ໥ᯘ፸፷ ፹፷፷፷፷

፷ ፸ᎀ፼፷ ፸ᎀ፽፷ ፸ᎀ፾፷ ፸ᎀ፿፷ ፸ᎀᎀ፷ ፹፷፷፷ Eruption of Kelud volcano is Brantas River Basin ፺፷፷፷ ፻፷፷ ̀ᬡɢɥ୲Paddy production Problem 1 ፹፼፷፷ Żɰ้ƥPaddy field area thought to be one of the biggest Riverbed degradation

፹፷፷፷ ፺፼፷ ᎯᎨᯙ ፺ factors to makeing serious effect There are 4 master plan executed in ፸፼፷፷ caused by sand mining ፸፷፷፷ ፺፷፷ on both problems ̀ᬡɢɥ୲ᯘᎻᯙ the Brantas River Basin Żɰ้ƥᯘ፸፷ ፼፷፷ Paddy field

፷ ፹፼፷ ፸ᎀ፼፷ ፸ᎀ፽፷ ፸ᎀ፾፷ ፸ᎀ፿፷ ፸ᎀᎀ፷ ፹፷፷፷ ፸፿፷፷ > Time going, economic factors ፸፽፷፷ ፸፻፷፷

increasing ፸፹፷፷ > The master plans were effective. ʡɕᯘȱʡᯙ ፸፷፷፷ ፿፷፷

But another problem occurs population ፽፷፷ ፸ᎀ፼፷ ፸ᎀ፽፷ ፸ᎀ፾፷ ፸ᎀ፿፷ ፸ᎀᎀ፷ ፹፷፷፷ ፽፷፷ ࡲŻ୲ ፼፷፷ ØV୲

> For example sedimentation in dam ᯙ ፺ Ꮄ ፽ reservoirs and river bed ፻፷፷ V5ᬊᬡðɯᬡØV୲ Problem 2 ፺፷፷ Dam sedimentation degradation ፹፷፷ ࡲŻ୲ᮦ ØV୲ᯘ፸፷ ፸፷፷ For the water resources management in the Brantas river basin, it is Storage ፷ ፸ᎀ፼፷ ፸ᎀ፽፷ ፸ᎀ፾፷ ፸ᎀ፿፷ ፸ᎀᎀ፷ ፹፷፷፷ important to clarify the effect of volcano-crust for the river.

Volcanic Activities of Kelud Volcano The purpose of this study > Kelud volcano ( 1,731m height ) is one of the high level active volcano located in Java Island. > It has 4 eruptions records since 1919.

To clarify the effect of Volcanic activities on > Almost all of the scale of eruptions were VEI 3 sediment conditions in Brantas Rivers > In each event, following phenomenon also occurred: 1) Lahar due to Phreatic explosion. 2) Plinian with pylocrastic flow Authors carried out numerical analysis applied to Kelut volcano eruption on 1990. 3) Lahar due to the breach of crater lake Table : scale of eruption of Mt. Kelud since 1919. ᎠᎬᎨᎹ ᎝ᎶᎳᎼᎴᎬ፯፸፷፽፧Ꮄ፺፰ ᎕ᎼᎴᎩᎬᎹ፧ᎶᎭ፧ᎫᎬᎨᎻᎯᎺ ፸ᎀ፸ᎀ ፺፹፺ ፼፸፸፷ ፸ᎀ፼፸ ፸ᎀ፷ ፾ ፸ᎀ፽፽ ᎀ፷ ፹፿፺ ፸ᎀᎀ፷ ፸፹፼ ፺፼

䋭㩷㪈㪉㪐㩷䋭 1 Numerical simulation carried out in this The latest eruption of active volcano ,Kelud 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)፧ > Pyroclastic flow simiulation( 2-D analysis)፧ > Pumice fall distribution calculation(1-D analysis)፧ Jawa Pos , 21st of Nov. 2007

Jawa Pos , 5th of Nov. 2007

Simulation model for lahar Input of Hydrograph

This calculation assumes that crater wall collapse triggering lahars. We calculate the hydrograph according to the volume of crater lake on 1990 eruption. ፧

Total discharge of Water is about

4,000,000 m3 Discharge(m3/s) Sediment supplied by M.P.M Time(s)፧ Red relief map around crater of Kelut volcano formula Relationship between time and discharge

Results of lahar calculation

ȸƂȡƏɻąK1 ȡȵƸശŬǃ ፯Ꮄ፰ minutes፯ą፰ ፸፷፵፷ᰮ ፷ᰮ፸ ፼፵፷ᰮ፸፷፵፷ ፸ᰮ፼ ፺፵፷ᰮ፼፵፷ ፼ᰮ፸፷ ፸፵፷ᰮ፺፵፷ ፷፵፼ᰮ፸፵፷ ፸፷ᰮ፸፿ ፷ᰮ፷፵፼ ፸፿ᰮ፻፿ ፻፿ᰮ፾፿

•․…‣ •․…‣ Kilometers Kilometers

Arrival time distribution of Lahar Distribution of depth of the flow

䋭㩷㪈㪊㪇㩷䋭 2 This figure shows sediment volume inflows into Brantas River within about 3 hours. ȸ΋OVØƥɻ ፯Ꮄ፰ ፸፷፵፷ᰮ ፼፵፷ᰮ፸፷፵፷ So the more time going, ፺፵፷ᰮ፼፵፷ the more volume flows ፸፵፷ᰮ፺፵፷ ፷፵፼ᰮ፸፵፷ into Brantas River. ፷ᰮ፷፵፼

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. Kilometers So, Lahar has serious effect on the conditions of Brantas Distribution of sediment depth after lahar flow down River.

Simulation model for pyroclastic flow Result of calculation of pyroclastic flow

ȸ΋OVØƥɻ ȡȵƸശŬǃhours ፯Ꮄ፰ ፯Ƹശ፰ ፸፷፵፷ᰮ ፷ᰮ፹ ፼፵፷ᰮ፸፷፵፷ Pyroclastic flow divided to two ፺፵፷ᰮ፼፵፷ ፹ᰮ፸፷ ፸፵፷ᰮ፺፵፷ layers; Surge and main body. ፸፷ᰮ፹፷ ፷፵፼ᰮ፸፵፷ ፹፷ᰮ፻፷ ፷ᰮ፷፵፼ Main body is dragged to surge. ፻፷ᰮ፽፷ ፽፷ᰮ፿፷ So, it is important to know the behavior of main body.

We followed Yamashita &

Miyamoto(1991)’s model in •․…‣ which the main body behavior Kilometers is treated as the dry particle Distribution of arrival time of Distribution of pyroclastic thickness flow. Schematic model of a pyroclastic flow pyroclastic flow of deposition፧

Numerical analysis model of pumice fall distribution It is difficult to model behavior of pumice fall precisely, because pumice fall has complex factors to simulate. This results show Pyroclastic flow doesn't have serious effect on Brantas River in short term. We use the geometrical model following Miyamoto(1993). 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.

Distribution of pumice fall is calculated Schematic model of volcanic plume by hight of plumes and wind direction.

䋭㩷㪈㪊㪈㩷䋭 3 Result of calculation of pumice fall distribution

A lot of pumice fall does not directly fall in the Brantas River. But After the heavy 10 cm rainfall, pumice fall is possible to flow down, changing forms to concentrated flow. 5 cm Because gradient of hillside over a wide range on Kelud volcano Distribution of pumice fall is determined by wind direction. is greater than 2 degree. In Brantas River Basin, everywhere is possible to damage by Distribution of gradient more than 2 degree pumice fall. about Kelud volcano

Summary and conclusion Summary and conclusion Lahar reach the main river course. Lahar is possible to make severe impact on the We can recognize the impact of eruptions on the sediment conditions in Brantas river basin. river is not so big in short term.

Pyroclastic flow does not reach the main course. However unstable sediment on the mountain slope is But it is considered the potential of sediment increased, so that the sediment yield will be increased. movement is increased after eruptions.

Pumice fall reach the main river course. But in short term the effect on changing sediment condition in Because these sediment is easy to move if heavy Brantas River Basin is not so large. rain falls. But pumice fall yields unstable sediments in Brantas River Basin.

Future studies of our plan Upper Reach Lower Reach After the execution of the previous simulation, We How much volume of sediment from upper estimate how much volume of sediment is necessary reach is necessary for lower reach to ? for lower reach. become equilibrium river bed condition? Then we can consider how much volume is allowed to flow down into dam reservoirs from upper reach. ?

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)

䋭㩷㪈㪊㪉㩷䋭 4 Thank you! Terima kasih!

䋭㩷㪈㪊㪊㩷䋭 5

A Bed-Porosity Variation Model - as a tool for integrated sediment management-

Prof. Masaharu Fujita DPRI, Kyoto University

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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. z 1 Q O 1 dz s 0 (1) t zo B x

Input data

Flow analysis

Temporal analysis of change Identification of grain size of grain size distribution and distribution type porosity Geometric parameters of Bed variation analysis grain size distribution

Analysis of change of grain Estimation of the porosity size distribution and porosity

Fig. 1 Flow chart of the presented bed-porosity variation model

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Line-2 where = porosity of bed material, 1.0 AT1 AT2 AT3 AT4 z = bed level, zo = a reference level, Anti-Talbot Area N3 Qs = sediment discharge and B2 N2 B=channel width. D3 Border-4 Border-2 N1 Porosity is dependent on the D2 D1 grain size distribution of bed Lognormal Area 0.5 Q material and its compaction degree. P2 P1 LN 1 Q2

In this paper, the compaction M3 Border-1 Border-3 C1 degree is considered empirically M2 C2 B3 and the porosity is assumed to be a M1 Talbot Area C3 function of geometric parameters of B1 T4 T3 T2 T1 0.0 grain size distribution. Line-1 0.0 0.5 1.0 fn 1 , 2, 3,...... (2) Fig.2 Diagram indicating Talbot, anti-Talbot and lognormal region 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. logd logd log d log d max peak (3) max 50 (4) logdmax logdmin log dmax log dmin

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The indices of Talbot and 0.4 anti-Talbot distributions are on Line-1 ( =0 and 0<<0.5) and Line-2 ( =1.0 and 0.5<<1.0) 0.3 in Fig.2. The indices of lognormal distribution are Porosity plotted just on the center point 0.2 (0.5, 0.5). The indices of the Measured other distribution are plotted Simulated (Tsutsumi et al, 2006) on the area of 0< <1 and 0.1 -0.1 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0<<1, apart from Line-1, Standard deviation Line-2 and the center point. L However, there is an area Fig. 3 Comparison between the measured porosity where no unimodal and the simulated one for lognormal distribution exists. From a distribution geometric analysis, an area 0.4 where unimodal distribution exists is surrounded by 0.3 Border-1, Border-2, =0 and =1.0 as shown in Fig.2. 0.2

It seems reasonable that Porosity the grain size distribution type 0.1 measured : dmax/dmin=1129 measured : dmax/dmin=201 is identified with the distance measured : dmax/dmin=53 simulated : dmax/dmin=10 (Sulaiman et.al., 2007) simulated: dmax/dmin=100 (Sulaiman, et.al., 2007) to the point ( , ) from Line-1, 0.0 Line-2 or the center point. 024681012 According to this criterion, the n T border line between Talbot Fig.4 Comparison between the measured porosity and distribution and lognormal the simulated one for Talbot distribution 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: (0.5 )2 0.25 (5) Border-4: (0.5 )2 0.75 (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

䋭㩷㪈㪊㪐㩷䋭

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.

0.01 ND001NS ND001NS

10 0.008

0.006

Bed level (m) 9.9 0 min 0 min 30 min 0.004 30 min 60 min 60 min 240 min 240 min 600 min Mean diameter of surface layer (m) 600 min 9.8 0.002 051015051015 Distance (m) Distance (m) (a) Bed variation (b) Mean diameter of surface layer

0.4 ND001NS

Lognormal Talbot 600 0.3 240

Porosity 0 min 30 min 60 60 min 240 min Time (min) 30 600 min 0 0.2 0 5 10 15 Disatance (m) 051015 Distance (m) (c) Porosity of surface layer (d) Type of grain size distribution

Fig.5 Simulation result on bed and porosity variation

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.

䋭㩷㪈㪋㪇㩷䋭 Background

Targets of sediment management • Disaster prevention A Bed-Porosity Variation Model • Reduction of bad influence of sediment on rivers • Effective utilization of sediment resources - as a tool for integrated sediment management- • Environment conservation

Tools • Software …… bed variation models Dr. Masaharu Fujita • Hardware ….. sabo dams, sediment flush gates, sediment bypass tunnel Mr. Muhammad Sulaiman Dr. Daizo Tsutsumi Ecological aspects • Habitat conservation • Disturbance to riverbeds DPRI, Kyoto University • Void of bed material

Reservoir sedimentation management Situation of bed material

Before flushing Impact of sediment flushing from Dashidaira dam and

Unazuki dam Shizumi ishi situation Uki ishi situation Fine sand densely packed No fine sand packed Lognormal type distribution Talbot type distribution Low porosity High porosity Just after flushing 1 year after flushing Lognormal type Talbot type

f f

d d

Grain size distribution type Void of bed material

Bimodal distribution Unimodal distribution Porosity Bed variation

f f Infiltration system in riverbeds f f Spaces among particles

log d log d log d log d Habitat

p p p p A bed variation model providing the information log(d) log d log d log d on the changes in porosity and grain size Talbot type Lognormal Anti Talbot distribution type of bed material type type

䋭㩷㪈㪋㪈㩷䋭 Basic equations ᎗ᎹᎬᎽᎰᎶᎼᎺ፧ᎩᎬᎫ፧ᎽᎨᎹᎰᎨᎻᎰᎶᎵ፧ᎴᎶᎫᎬᎳ ᎄᎪᎶᎵᎺᎻᎨᎵᎻ Bh Q 0 Continuity equation of water t x Continuity equation of sediment

C 2 S z Q D 1 2 Q T 1 Qs z qS gBh gBh ib i f 1 dz 0 1 0 Energy equation for flows t x D 2 Bh T O E U t zo B x t x

z 1 Qs Continuity equation of sediment O 1 dz 0 Continuity equation of sediment with grain size dj t zo B x z 1 Qsj 1 p dz 0 z Q O j Continuity equation of sediment with 1 sj t zo B x O 1 p j dz 0 t z B x grain size dj o f B q f ! j 1 s Sj j0 z z t 0 B = channel width, h = water depth, Q = water discharge, t = time, x = distance in t 1 aBs x a t stream wise direction, = porosity of bed material, z = bed level, zo = a reference level, Qs = sediment discharge, g = gravity acceleration, ib = bed slope, if = friction f j 1 BsqSj f j z slope, j = grain size grade, p = mixing ratio of a grade j in bed material and Q = z t 0 j sj sediment discharge of a grain size grade j t 1 aBs x a t

A proposed model Porosity estimation

Compaction degree ់ᎪᎶᎵᎺᎻᎨᎵᎻ Grain size distribution zb 1 Q z 1 Qsj "# S f n , 2 , 3,...... O0 1 dz 0 O 1 p j dz 0 1 t B x t zo B x 1, 2, 3….= characteristic parameters of Ꮑ ᎍᎳᎶᎾ grain size distribution Lognormal distribution: 1 Bed surface z =zb Sediment discharge QS ᎗ᎶᎹᎶᎺᎰᎻᏀ፧ t,x,z Talbot distribution: 1 d max / d min 2 nT Ꮏ Bottom z=0 Particle packing simulation and measurement method

A bed variation model A bed-porosity variation model

Water discharge Water discharge

Sediment Grain size distribution Sediment Grain size distribution Flow analysis transport of bed material Flow analysis transport of bed material

Constant porosity Porosity Implicit equations Geometric Geometric parameters Bed elevation parameters Bed elevation

䋭㩷㪈㪋㪉㩷䋭 t+$t Main routine and subroutine Temporally calculation of pj

Input data

t Flow analysis Subroutine Bqs, j pt 1 t aB$x $x$t $ j 1 pt t x Identification of grain j t Temporal analysis of change of Bq size distribution type 1 t aB$x s $x$t grain size distribution and porosity 1 x

Characteristic parameters Bed variation analysis of grain size distribution Sediment balance within the surface layer at time t Analysis of change of grain size Estimation of distribution and porosity the porosity

MacCormack scheme Water depth, water discharge and bed level h U1 / B Q U 2 U C t x z z U3 O 1 dz z zo O dz z R z zo zo C S D T C S z Q D T R z zo O dz D T Bh C 0 S where z 1 Q 2 D T D T o D 2 T D T E D gBh T U Q C D gBh ib i f T 2 Bh D z T D T D T Qs DO 1 dzT E 0 U $ $ $ D T E z U z U 3 R E B U o where

$ z$z z $R R z t t R(z t ) O dz O dz zo zo

$ t$t t t $ z t ! 0 R 1 1 a 2 z Change in bed elevation

t$t t t t$t t $ z t 0 $R a $z a U 3 1 1 1 z t ! 0 $z 1 1 t 1 2

$ t t t a $U Bed degradation Bed aggradation z t 0 $z 1 1 3 1 t $z 1 t t+$t a t+$t t $ t $ t t+ t t+ t t t+$t $ $ $ % t+$t t % z from t to t+ t t+ t % % 1

A layer bed model Grain size distribution at t+$t

䋭㩷㪈㪋㪊㩷䋭 Change in grain size distribution Classification of grain size distribution type z 1 Qsj Lognormal type p t, x, z dz 0 O j F 2 V t zo B 1 x 1 ln d ln d p ln d expG mg W , G 2 W 1 L 2 L H 2 L X A layer bed model p1 j p1 j 1 Bqsj 1 p2 j z Talbot and anti Talbot types z t ! 0 1 2 t 1 t 1 aB x 1 a t n 1 1 1 C d S f d D T E dmax U p1j p1 j 1 Bqsj p1 j z z t 0 1 Modified Talbot and anti Talbot types t 1 t 1 aB x a t 1 1 n C S T 1 d max / dmin D logd logdmin T f d D T E log d logd U max min 2 nT

Identification Indices for lognormal distribution Geometric parameter of grain size distribution f

Line-2 1.0 AT1 AT2 AT3 AT4 50% Anti-Talbot Area N3 log dmax log d50 B2 N2 D3 Lognormal type log dmax log dmin Border-4 Border-2 N1 D2 dmin d50 dmax d D1 Lognormal Area 0.5 100 P2 P1 LN Q1 Q2 P -. logd logd 80 LN1 M3 max peak Border-1 -./ Border-3 C1 M 2 60 .- logd logd C2 max min B3 M1 Talbot Area 40 C3

B1 (%) finer Percent

T4 T3 T2 T1 0.0 20 Line-1 LN LN2 0.0 0.5 1.0 3 0 d 0.01 0.1 1 10 100 1000 dmin peak dmax d d (mm)

Indices for Talbot distribution Indices for anti-Talbot distribution

Line-2 Line-2 1.0 1.0 AT1 AT2 AT3 AT4 AT1 AT2 AT3 AT4 Anti-Talbot Area Anti-Talbot Area N3 N3

B2 N2 B2 N2 D3 Talbot type D3 Anti-Talbot type Border-4 Border-4 Border-2 N1 Border-2 N1 D2 D2

D1 D1 Lognormal Area Lognormal Area 0.5 100 0.5 100 P P LN Q1 Q P P LN Q1 Q 2 1 2 T1 (nT=1.1) 2 1 2 AT3 80 T2 (nT=2) 80 M3 Border-1 M3 Border-1 C1 C1 AT Border-3 T3 (nT=4) Border-3 4 M2 60 M2 60 C2 T4 (nT=16) C2 B3 B3 nT=0.2 M1 T1 M1 Talbot Area 40 Talbot Area 40 C3 C3

Percent finer (%) finer Percent nT=0.4 Percent finer (%) AT1 B1 T2 B1 AT T T 2 nT=0.6 T4 T3 T2 1 T T4 T3 T2 1 20 0.0 20 3 0.0 Line-1 T4 Line-1 nT=0.9 0.0 0.5 1.0 0.0 0.5 1.0 0 0 0.01 0.1 1 10 100 1000 0.01 0.1 1 10 100 1000 d (mm) d (mm)

䋭㩷㪈㪋㪋㩷䋭 Domain of each type Identification

Line-2 Line-2 1.0 1.0 AT1 AT2 AT3 AT4 AT1 AT2 AT3 AT4 Anti-Talbot Area Anti-Talbot Area N3 N3

B2 N2 B2 N2 D3 D3 Border-4 Border-4 Border-2 N1 Border-2 N1 D2 D2

D1 D1 Lognormal Area Lognormal Area 0.5 0.5 P P LN Q1 Q P P LN Q1 Q 2 1 2 2 1 2 100

M3 Border-1 M3 Border-1 Border-3 C1 Border-3 C1 80

M2 M2

C2 C2 B3 B3 60 M1 Talbot Area M1 Talbot Area C3 C3 40 B1 B1 Percent finer (%) finer Percent T4 T3 T2 T1 T4 T3 T2 T1 0.0 0.0 20 M Line-1 Line-1 1 M2 M3 0.0 0.5 1.0 0.0 0.5 1.0 0 0.1 1 10 100 1000 d (mm)

Identification Identification

Line-2 Line-2 1.0 1.0 AT1 AT2 AT3 AT4 AT1 AT2 AT3 AT4 Anti-Talbot Area Anti-Talbot Area N3 N3

B2 N2 B2 N2 D3 D3 Border-4 Border-4 Border-2 N1 Border-2 N1 D2 D2

D1 D1 Lognormal Area Lognormal Area

0.5 100 0.5 P P LN Q1 Q P P LN Q1 Q 100 2 1 2 N1 2 1 2

80 80 M3 Border-1 N3 M3 Border-1 Border-3 C1 Border-3 C1 M2 M2 60 60 N2 P1 C2 C2 B3 B3 Q2 M1 Talbot Area M1 Talbot Area 40 C3 40 C3 Q P Percent finerPercent (%) 1 2 B1 B1 Percent finer (%) finer Percent 20 T4 T3 T2 T1 T4 T3 T2 T1 0.0 20 0.0 Line-1 Line-1 0 0.0 0.5 1.0 0.0 0.5 1.0 0 0.01 0.1 1 10 100 1000 0.1 1 10 100 1000 d (mm) d (mm)

100 O-1 O-2 80 O-3 60 F-1 Identification F-2 Porosity and geometric parameter 40 F-3 Percent finer (%) finer Percent 20

0 1.0 0.001 0.01 0.1 1 10 100 d (mm) 0.9 Anti-Talbot Area Two size particle mixture 100 A-1 A-2 0.8 80 A-3 ፷፵፻ 0.7 H H 60 A-4 2 4 A-5 ፷፵፺፼ H 40 A-6 0.6 1 ፷፵፺ Percent finer (%) finer Percent 20 Lognormal Area ፷፵፹፼ 0.5 0 0.1 1 10 100 1000 ፷፵፹ 0.4 O3 d (mm) ǀ෇Ÿ ፷፵፸፼ 100 0.3 O2 H-1 A Talbot 3 H-2 Porosity ፷፵፸ H 80 0.2 A4 O1 5 Lognormal H-3 H3 A2 Talbot--Log-normal H-4 ፷፵፷፼ Talbot Area 60 0.1 Log-normal--Anti Talbot H-5 ፷ A1 A H Bimodal 40 H-6 6 6 ፷ ፷፵፹ ፷፵፻ ፷፵፽ ፷፵፿ ፸

0.0 (%) finer Percent A5 F3 F2 F1 20 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Ratio of;̐ʖňɯ finer particle 0 0.1 1 10 100 100 d (mm)

䋭㩷㪈㪋㪌㩷䋭 Porosity and geometric parameter Porosity and geometric parameter

Talbot distribution Lognormal distribution 0.4 0.4 0.3

0.3 0.2 Porosity

Porosity 0.2 0.1 measured : dmax/dmin=1129 measured : dmax/dmin=201 Measured measured : dmax/dmin=53 simulated : dmax/dmin=10 (Sulaiman et.al., 2007) Simulated (Tsutsumi et al, 2006) simulated: dmax/dmin=100 (Sulaiman, et.al., 2007) 0.1 0.0 -0.1 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 024681012 n T Standard deviation L

Sediment supply Bed variation ᎈᎷᎷᎳᎰᎪᎨᎻᎰᎶᎵ 10.0 Flow Case 1

፹ (m) level Bed 9.9 ᎘ᎄ፷፵፷፸፧Ꮄ ፶Ꮊ 0 min 30 min 60 min 240 min 600 min 9.8 051015 ፸፶፸፷፷ Disatance (m)

Nosediment supply ፸፼፧Ꮄ Flow 10.0 ᎊᎨᎺᎬ፧፸ ᎉᎬᎫ፧ᎴᎨᎻᎬᎹᎰᎨᎳᎁ፧᎛ᎨᎳᎩᎶᎻ፧ᎻᏀᎷᎬ

Bed level (m) 9.9 ᎚ᎼᎷᎷᎳᎰᎬᎫ፧ᎺᎬᎫᎰᎴᎬᎵᎻᎁ፧᎔ᎰᎫᎫᎳᎬ፧ᎺᎰᏁᎬ፧ᎶᎭ፧ᎩᎬᎫ፧ᎴᎨᎻᎬᎹᎰᎨᎳ፧ᎽᎬᎹᏀ፧ᎳᎰᎻᎻᎳᎬ 0 min Case 2 30 min ᎊᎨᎺᎬ፧፹ 60 min 240 min ᎉᎬᎫ፧ᎴᎨᎻᎬᎹᎰᎨᎳᎁ፧᎓ᎶᎮᎵᎶᎹᎴᎨᎳ፧ᎻᏀᎷᎬ 600 min 9.8 ᎕Ꮆ፧ᎺᎬᎫᎰᎴᎬᎵᎻ፧ᎺᎼᎷᎷᎳᏀ፧ 0 5 10 15 Disatance (m)

100 Lognormal Talbot Flow x=10m Grain size distribution Grain size 240 80 0 min of surface layer distribution type 30 min 60 min 60 60 240 min 600 min Case 1 Case 1 10 40 Percent finer (%) Percent finer

Talbot to lognormal (min) Time 5 20 Sediment supply 0 0 0.001 0.01 d (m) - / - / Disatance (m) 100 Lognormal Talbot Flow x=10m 600 80 0 min 30 min 60 min 240 60 240 min 600 min 60 Case 2 40 Percent (%) finer Case 2 Time (min) 30 20 Lognormal to Talbot No sediment supply 0 0 0.001 0.01 d (m) 0 5 10 15 Disatance (m)

䋭㩷㪈㪋㪍㩷䋭 0.4 Sediment supply Porosity of Case 1 surface layer ᎈᎷᎷᎳᎰᎪᎨᎻᎰᎶᎵ

0.3 100 x=10m ፹

Porosity ᎘ᎄ፷፵፷፹፧Ꮄ ፶Ꮊ 0 min 80 0 min 30 min 30 min 60 min 60 min 60 240 min Flow 600 min 240 min 600 min 40 ᎞ᎬᎰᎹ Percent finer (%) Percent finer 0.2 20 051015 No sediment supply Disatance (m) 0 0.001 0.01 ፸፶፸፷፷ ፷፵፼፧ᎪᎴ d (m)

100 x=10m 0.4 No sediment supply 80 0 min ፸፼፧Ꮄ 30 min 60 min 60 240 min 600 min 40 d1=2cm, d2=0.05cm Percent finer (%) finer Percent

20 Sediment supply 0 0.3 Case 3 0.001 0.01 d (m) Porosity Bed material d (90%), d (10%) Case 2 0 min 1 2 30 min Supplied sediment d very little Flow 60 min 2 240 min 600 min Case 4 0.2 0 5 10 15 Bed material d1(70%), d2(30%) Disatance (m) No sediment supply

0.06 Sediment supply Deposition depth Deposition depth 0.05 0 min 240 min 30 min 360 min 0.04 120 min 0.03 Flow Case 3

0.02

Deposition depth(m) 0.01 0.06 Constant porosity (Sediment supply) 0 Not constant porosity (Sediment supply) Not constant porosity (No sediment supply) -0.01 0.04 051015 Constant porosity (No sediment supply) Disatance (m)

0.02 0.06 No sediment supply

0.05 0 min 30 min 5 min 60 min Deposition depth (m) depth Deposition 0.04 10 min 120 min 0

0.03 Flow

0.02 -0.02

Deposition depth (m) 0.01 051015 Case 4 Distance (m) 0

-0.01 0 5 10 15 Disatance (m)

1 0.5 Sediment supply Sediment Supply 0 min 60 min Ratio of finer 10 min 120 min Porosity of 0 min 60 min 30 min 240 min 0.8 10 min 120 min 0.4 30 min 240 min particle surface layer

0.6 Flow Case 3 0.3 Case 3

0.4 Porosity 0.2 Ratio of finer sediment 0.2 0.1 Flow 0 0 051015 051015 Disatance (m) Disatance (m)

1 No sediment supply 0.5 0 min 30 min No sediment supply 5 min 60 min 0 min 30 min 10 min 120 min 0.8 5 min 60 min 0.4 10 min 120 min

0.6 Flow 0.3

0.4 Porosity 0.2

Case 4 Ratio of sediment finer Case 4 0.2 0.1 Flow

0 0 0 5 10 15 051015 Disatance (m) Disatance (m)

䋭㩷㪈㪋㪎㩷䋭 Sediment supply Sediment supply x=14.5m x=14.5m x= 5.0m x= 5.0m 0 0 Vertical Case 3 distribution of 2 Conclusions 2 ratio of finer Conclusions

4 4 particle and porosity Identification method for grain size distribution

Layer No. 6 Layer No. Layer 6 type 8 8 T=360min T=360min The relation between the geometric parameter 10 10 of grain size distribution and the porosity 0 0.1 0.2 0.3 0.4 0.5 No sediment supply No sediment supply 0 0.2 0.4 0.6 0.8 1 x=14.5m Ratio of finer sediment Porosity x= 14.5m 0 x= 5.0m 0 x= 5.0m Development of a bed-void variation model

2 2

4 4

Layer No. Layer 6 Layer No. Layer 6 Case 4 8 8 T=120min T=120min

10 10 0 0.2 0.4 0.6 0.8 1 0 0.1 0.2 0.3 0.4 0.5 Ratio of finer sediment Porosity

䋭㩷㪈㪋㪏㩷䋭

Reservoir Sediment Management Measures in Japan and those appropriate selection strategy

Dr. Tetsuya Sumi Kyoto University

䋭㩷㪈㪋㪐㩷䋭

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

䋭㩷㪈㪌㪈㩷䋭

Classification Place Details of sediment control measures Examples in Japan

Reduction of sediment production by hillside and valley works Upstream Regulation of reservoirs and sediment by erosion control dams Sabo area, Changing from sediment check dams to reservoirs and slit dams sediment control dams (slit dams) Reducing sediment Reduction of discharged sediment and river course stabilization flowing into by channel works reservoirs Regurally excavating and recycling for End of Sediment check Miwa Dam, Koshibu Dam, Nagashima Dam, aggregate or sediment supply to reservoirs dam Matsukawa Dam, Yokoyama Dam downstream river End of Asahi Dam, Miwa Dam, Koshibu Dam, Matsukawa Sediment bypass reservoirs Dam, Yokoyama Dam Sediment Sabaishigawa Dam Sediment routing sluicing Dashidaira Dam-Unazuki DamᯘCoordinated sluicingᯙ Sediment Inside Non-gate botom outlets Masudagawa Dam management reservoirs ᯘnatural flushingᯙ Density current Botom outlets for flood control Koshibu Dam, Futase Dam, Kigawa Dam venting Non-gate conduits with curtain wall Katagiri Dam

Selective withdrawal works Yahagi Dam

Drawdown Sediment flushing outlet Dashidaira Dam-Unazuki DamᯘCoordinated flushingᯙ flushing Partial flushing Inside Sediment flushing without Sediment scoring gate Senzu Dam, Yasuoka Dam reservoirs drawdown

Sediment scoring pipe Ikawa Dam

Excavating & Miwa Dam, Koshibu Dam, Sakuma Dam, Hiraoka Dam, Recycling for concrete aggregate Dreging Yasuoka Dam Soil improving material, Farm Land Miwa Dam, Yanase Dam filling, Banking material Sediment replacing inside reservoir Sakuma Dam Akiba Dam, Futase Dam, Miharu Dam, Nagayasuguchi Sediment supplying to downstream rive Dam, Nagashima Dam

Figure 1. Classification of Reservoir Sedimentation management in Japan

፸Ƃʇ ᎖Ꮀ ᎋ፳፧᎚᎗ ᎊᎨᎷᎨᎪᎰᎻᏀ፴ᎰᎵᎭᎳᎶᎾ፧ᎹᎨᎻᎰᎶ፧ᎨᎵᎫ፧᎙ᎬᎺᎬᎹᎽᎶᎰᎹ፧᎓ᎰᎭᎬ ፹ Ǫ໑ ᎚ᎬᎵᏁᎼ ᎚ᎎ ፺ Ƿ൲ ᎠᎨᎺᎼᎶᎲᎨ ᎚ᎎ፳፧ᎋ፳፧᎗ᎍ ፻ Ȩ¾ ᎒ᎨᎺᎨᎮᎰ ᎚ᎎ፳፧᎗ᎍ ፸፷፷፷፷፷ ፼Ƃശ ᎖ᎶᎴᎨ ᎚ᎎ፳፧᎗ᎍ No measures (from inner factors) ፽iΚ ᎛ᎶᎲᎰᎾᎨ ᎚ᎎ ᎊᎯᎬᎪᎲ፧ᎫᎨᎴ ፾ȳȮ ᎔ᎰᎼᎹᎨ ᎚᎗ ፿Ϳ ᎏᎰᎹᎨᎶᎲᎨ ᎋ፳፧᎗ᎍ ᎍᎳᎼᎺᎯᎰᎵᎮ ᎀ ̂ɝശ ᎚ᎨᎲᎼᎴᎨ ᎋ ፸፷ ɝ˂ ᎏᎨᎲᎼᎾᎨ ᎌ፳፧ᎋ ፸፷፷፷፷ ᎚ᎪᎶᎹᎰᎵᎮ፧ᎮᎨᎻᎬ ፸፸ ʇ1 ᎐ᎲᎨᎾᎨ ᎚᎗፳፧ᎌ፳፧ᎋ፳፧᎗ᎍ ፸፹ ͪɕ ᎠᎨᎴᎨᎮᎼᎪᎯᎰ ᎚ᎎ፳፧᎗ᎍ ᎚ᎪᎶᎹᎰᎵᎮ፧ᎷᎰᎷᎬ ፸፺ Œ΢ ᎈᎲᎰᎩᎨ ᎌ፳፧ᎋ፳፧᎗ᎍ ፸፻ Ô˂ ᎔ᎰᎾᎨ ᎉ፳፧ᎌ፳፧ᎋ፳፧ᎊᎋ ᎉᏀᎷᎨᎺᎺᎰᎵᎮ ፸፼ Ù͈ ᎔ᎨᎲᎰᎶ ᎌ፳፧ᎋ፳፧ᎊᎋ ፸፷፷፷ ፸፽ ̪ʎ ᎒ᎶᎺᎯᎰᎩᎼ ᎌ፳፧ᎊᎋ ᎌᎿᎪᎨᎽᎨᎻᎰᎵᎮ ᡳ ፸፾ ʋ1᎔ᎨᎻᎺᎼᎲᎨᎾᎨ ᎉ፳፧ᎌ፳፧ᎊᎋ ᡨ ፸፿ Ź ᎈᎺᎨᎯᎰ ᎉ ᡫ ᎋᎹᎬᎫᎮᎰᎵᎮ ፸ᎀ üᬊ ᎋᎨᎺᎯᎰᎫᎨᎰᎹᎨ ᎍ ᡰ ᡧ ᡥ ፹፷ ʽƙȼ ᎜ᎵᎨᏁᎼᎲᎰ ᎍ ᡯ ᡬ ᡢ ᡪ ᡱSediment check dam, ᎙ᎬᎺᎬᎹᎽᎶᎰᎹ፧᎓ᎰᎭᎬᎄᎊᎈ᎗፶᎔ᎈ᎚ ፸፷፷ ᡮ ᡣ ᡲ Sediment replenishment ᎊᎋ፧ᯪ᫝ᎊᎯᎬᎪᎲ፧ᎫᎨᎴ ᡦ ᎍ፧ ᯪ᫝ᎍᎳᎼᎺᎯᎰᎵᎮ፧፯ᎋᎹᎨᎾ፧ᎫᎶᎾᎵ፰ ᡭ ᡤ ᡩ ᡵ Sediment bypass, Sluicing ᎗ᎍ ᯪ᫝ᎍᎳᎼᎺᎯᎰᎵᎮ፧፯᎗ᎨᎹᎻᎰᎨᎳ፧ᎫᎹᎨᎾ፧ᎫᎶᎾᎵ፰ ᡴ ᎚ᎎ ᯪ᫝᎚ᎪᎶᎹᎰᎵᎮ፧ᎮᎨᎻᎬ Sediment flushing, Sediment scoring gate ᎚᎗ ᯪ᫝᎚ᎪᎶᎹᎰᎵᎮ፧ᎷᎰᎷᎬ ፸፷ ᎉ ᯪ᫝ᎉᏀᎷᎨᎺᎺᎰᎵᎮ ፷፵፷፷፸ ፷፵፷፸ ፷፵፸ ፸ ፸፷ ᎌ ᯪ᫝ᎌᎿᎪᎨᎽᎨᎻᎰᎵᎮ ᎋ ᯪ᫝ᎋᎹᎬᎫᎮᎰᎵᎮ ᎊᎨᎷᎨᎪᎰᎻᏀ፴ᎰᎵᎭᎳᎶᎾ፧ᎹᎨᎻᎰᎶᎄᎊᎈ᎗፶᎔ᎈ᎙

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).

䋭㩷㪈㪌㪉㩷䋭 Contents of presentation

• Reservoir sedimentation in Japan Reservoir Sediment Management Measures • Reservoir sediment management in Japan and those appropriate selection strategy measures in Japan • Sediment bypassing • Sediment flushing and environmental Kyoto University issues • Promotion strategy of reservoir sediment Tetsuya SUMI management • Conclusions

•ReservoirNational Inventory of reservoir sedimentation Total sedimentation losses 3 sedimentation2730 dams (>15m high) with 23 billion m capacity. ፸፷፷ ᎔ᎼᎳᎻᎰ፴ᎷᎼᎹᎷᎶᎺᎬ፯᎔፵᎖፵᎓፵᎐፵᎛፰ 3 ᎔ᎼᎳᎻᎰ፴ᎷᎼᎹᎷᎶᎺᎬ፯᎗፵ᎎ፵፰ inSedimentation Japan progress of all reservoirs over 1 million m ᎔ᎼᎳᎻᎰ፴ᎷᎼᎹᎷᎶᎺᎬ፯᎞፵᎙፵ᎋ፵᎗፵ᎊ፵፰ ፿፷ ᎞ᎨᎻᎬᎹ፧ᎷᎶᎾᎬᎹ have been reported annually to the government from 1980s. ᎐ᎹᎹᎰᎮᎨᎻᎰᎶᎵ ፽፷ ᎔ᎼᎵᎰᎪᎰᎷᎨᎳ፧ᎾᎨᎻᎬᎹ 3 In 922 dams of 18 billion m volume, ፻፷ ᜒ total sedimentation 7.4% ፹፷

total sedimentation 7.4% ᎚ᎬᎫᎰᎴᎬᎵᎻᎨᎻᎰᎶᎵ፧ᎳᎶᎺᎺ፯፬፰ ፷ annual loss 0.24%/yr ፷ ፸፷፹፷፺፷፻፷፼፷፽፷፾፷፿፷ᎀ፷፸፷፷ ᎠᎬᎨᎹᎺ፧ᎨᎭᎻᎬᎹ፧ᎫᎨᎴ፧ᎪᎶᎴᎷᎳᎬᎻᎰᎶᎵ

Itoigawa-Shizuoka – Some hydroelectric dams constructed before World War II more than Tectonic Line 50 years old D 60 to 80 %, but problems are depend on the cases. – Many cases from 1950 and 1960 through the high economic growth Sediment yield period more than 30 years old D beyond 40 %. Median Tectonic Line potential map – From 1960s, large numbers of multi-purpose dams D 10 to 30 % of Japan Maintaining effective storage capacity is critical for flood control and water supply.

mǹ˿3/kmǓ4ǐ2/yr4 Total average sedimentation rate 7.4% (1.35 /18.3 billion m3)

Need for reservoir sedimentation management Comprehensive Management of Sediment Routing System 3 points in a River Basin and Connected Shoreline Scale Safety Management for Dams and Rivers Check dam Balancing of sediment Sedimentation To prevent the siltation of intake and other hydraulic transport from the facilities and aggradations of upstream rivers source of the river to the Storage coast reservoir Sustainability of Water Storage Volume Riverbed Lack of Comprehensive Management of Sediment Routing degradation Comprehensive Management of Sediment Routing sediment supply System in a River Basin and Connected Shoreline Scale Sediment flow River monitoring To prevent riverbed degradation, river morphology change environment Coastal erosion Bed load and coastal erosion caused by shortage of necessary change Suspended load sediment supply from upstream including dams Wash load

䋭㩷㪈㪌㪊㩷䋭 1 Yasuoka dam(1936,11MCM) Miwa dam(1959,30MCM) Hiraoka dam(1951,43MCM) Koshibu dam(1969,58MCM) Tenryu River Mouth Sediment Sakuma suppy dam(1956,327MCM) Yasuoka dam (1936)

Akiba dam(1958,35MCM) 1946 Hiraoka dam (1951) Sakuma dam (1956) Akiba dam (1958) Miwa dam (1959) 1961 Dicrease Koshibu dam (1969) Tenryu River, A=5,090km2 2001

Reservoir sedimentation in Sakuma dam Future estimation of reservoir sedimentation in Sakuma dam

፺፹፷

Ϳ᭫ᮋ ፯ᎌ᎓Ꮄ፰

፺፷፷ ဎ I Œ࠮˾͒ช̪ČŻɕ ፹፿፷

201yr ፹፽፷ ᭚ᮗ᭤᭳ĭဎ 101yr ᎌ᎓፹፻፽፵፼Ꮄ ፹፻፷ ࠮1ɪŻ ɊŻɕ ፹፹፷

̂ɝശ᭫ᮋâܣİᬡǉဎ ፹፷፷

፸፿፷ ̂ɝശ͒ช̪ ɽČȡŻ˿ ɊŻɕ iƸˑŻ˿ ØV፸፷፸ŗ ፸፽፷ ØV፹፷፸ŗ âܣİǉưଙᬡ፸፶፹ưଙᬚØVᯘǷ൲᭫ᮋᬡ˓SΟᯙ ፸፻፷ ƨ˂፼፼ªȸɻǉဎ âܣİǉưଙᬡ፸፶፺፵፹ưଙᬚØVᯘͿ᭫ᮋᬡ˓SΟᯙ Ϳ^ǡࠄΏဎ ፸፹፷ Ƅǽɋʧˮ¥ Ϳ᎗᎚ČŻ˿ J-Power (EPDC) ፸፷፷ ፷ ፼ ፸፷ ፸፼ ፹፷ ፹፼ ፺፷ ፺፼ 1956 Power generation ᭫ᮋ᫾ᬼᬡं෼፯ᎲᎴ፰ Gravity concrete Height=155.5 m

Tenryu River Dam Reservoir sediment management measures in Japan Sakuma dam Redevelopment Project Excavating Sediment check dam

HSRS: Hydro-suction Diversion weir Sediment Removal System Akiba dam Afforestation Sediment Transport: Sediment bypass tunnel Transport sediment in reservoir by dredging or other methods ᡤĲ˲ªȡü ᡥ ᮦ ̂ɝശc Density Current Venting ĳ\SluicingZS Sakuma dam Dredging Trucking FlushingxfZS ŒAkiba΢c dam Reducing Density current venting Sediment Inflow Sediment scoring gate ĴᡦHSRS+Sedimentʎùŗô ᡢİSedimentVsGt Bypass\k pTunnel ˲ªȡü bypass+Sediment዇Vkp Sediment Routing ዇ʻ¥৓਽ Transport ᡣHSRS+Sedimentıʎùŗ Bypass+Sedimentô዇Vkp዇ Transportʻ¥৓਽ ᡨĶHSRS+Sedimentʎùŗô዇Vk bypass+Sedimentp዇ʻ¥৓਽ ǉ1OVદx Sediment Removal ĵᡧSedimentVsGt Bypass\kp Tunnel Sediment supply Transport (Twoዄ cdams)ਗ਼χዅ (Two ዄdams) cਗ਼χዅ

䋭㩷㪈㪌㪋㩷䋭 2 Reservoir sediment management measures in Japan Excavating Sediment check dam Typical sediment management Diversion weir dams in Japan

Afforestation Sediment bypass tunnel New project Unazuki dam Matsukawa dam Flushing Dashidaira dam Dredging Trucking Yahagi dam

Miwa dam Bypassing Reducing Density current venting Sediment Inflow Koshibu dam Sediment scoring gate ˲ªȡü Sediment Routing Asahi dam Sakuma and Akiba dams Nunobiki dam Sediment Removal Bypassing ǉ1OVદx Sediment supply

Nagano Outline of Miwa dam Sediment bypassing dams in the Tenryu river Tokyo Sediment trap weir (H=15.0m) world Nagoya Dam 1959, H=69m Tunnel Tunnel General Design Design Tunnel Tunnel Cross Operation V=29.95 MCM No Name of Dam Country Length Slope Discharge Velocity Completion Shape Section Frequency (m) (%) (m3/sᯙ (m/s) Diversion weir (H=20.5m) 2 (B×H(m)ᯙ A=311km

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 Sediment bypass tunnel 3 Miwa Japan 2004 Horseshoe 2r = 7.8 4,300 1 300 10.8 - 2 Under 2005, A=50m L=4300m 4 Matsukawa Japan construction Hood 5.2×5.2 1,417 4 200 15 - Bed and suspended load 180,000 m3 Purpose: 5 Egshi Switzerland 1976 Circular r = 2.8 360 2.6 74 9 10days/yr Wash load 535,000m3 6 Palagnedra Switzerland 1974 Horseshoe 2r = 6.2 1,800 2 110 9 2ᰮ5days/yr Multipurpose A= ᰮ Flood control 7 Pfaffensprung Switzerland 1922 Horseshoe 21.0m2 280 3 220 10ᰮ15 200days/yr Irrigation 8 Rempen Switzerland 1983 Horseshoe 3.5×3.3 450 4 80 ᰮ14 1ᰮ5days/yr 9 Runcahez Switzerland 1961 Horseshoe 3.8×4.5 572 1.4 110 9 4days/yr Water power

(Five bypass tunnels in Switzerland by Visher et al., 1997) Wash load Miwa dam

Sediment bypass (Miwa dam) Diversion weir Bypass operation in 2006

Sediment check dam

Bypass discharge

Sediment check dam Diversion weir

7.5m

L=4,300m

Tunnel outlet 7.5m

䋭㩷㪈㪌㪌㩷䋭 3 Sediment flushing in the Kurobe River Sediment flushing dams in the World ᎐ᎵᎰᎻᎰᎨᎳ ᎔ᎬᎨᎵ፧ᎈᎵᎵᎼᎨᎳ ᯡᯟ፯᎔ᎬᎨᎵ ᎙ᎬᎺᎬᎹᎽᎶᎰ ᎈᎽᎬᎹᎨᎮᎬ ᎋᎨᎴ ᎚ᎻᎶᎹᎨᎮᎬ ᎍᎳᎼᎺᎯᎰᎵᎮ ᎍᎳᎼᎺᎯᎰᎵᎮ ᎋᎨᎴ ᎚ᎬᎫᎰᎴᎬᎵᎻ ᎈᎵᎵᎼᎨᎳ Ꮉ፧᎓ᎰᎭᎬ ᎍᎳᎼᎺᎯᎰᎵᎮ Kurobe river ᎕ᎨᎴᎬ፧ᎶᎭ፧ᎋᎨᎴ ᎊᎶᎼᎵᎻᎹᏀ ᎏᎬᎰᎮᎯᎻ ᎊᎨᎷᎨᎪᎰᎻᏀ ᎋᎼᎹᎨᎻᎰᎶᎵ ᎍᎹᎬᎸᎼᎬᎵᎪᏀ Kurobe river ᎪᎶᎴᎷᎳᎬᎻᎬᎫ ᎐ᎵᎭᎳᎶᎾ፧፯᎔ᎈ᎚፰ ᎙ᎼᎵᎶᎭᎭ፰ ፯ᎄᎊᎈ᎗፶ ᎋᎰᎺᎪᎯᎨᎹᎮᎬ ፯Ꮄ፰ ፯ᎊᎈ᎗፰ ᯘᎯᎹᎺᯙ ፯፸፶፧ᏀᎹ፰ 2 ፯ᎴᎰᎳᎳᎰᎶᎵ፧Ꮄ፺፰ᯡᯙ ᯘᎄᎊᎈ᎗፶᎔ᎈ᎙፰ ᎔ᎈ᎚፰ ፯Ꮄ፺፶Ꮊᯙ Catchment area = 682km ፯ᎴᎰᎳᎳᎰᎶᎵ፧Ꮄ፺፰ River length = 85km ᎋᎨᎺᎯᎰᎫᎨᎰᎹᎨ᫝ ᎑ᎨᎷᎨᎵ ፸ᎀ፿፼ ፾፽፵፾ ᎀ፵፷፸ ፷፵፽፹ ፷፵፷፷፽፾፻ ፸፻፵፼ ፹፷፷ ፸፹ ፸ ᎜ᎵᎨᏁᎼᎲᎰ ᎑ᎨᎷᎨᎵ ፹፷፷፸ ᎀ፾ ፹፻፵፾ ፷፵ᎀ፽ ፷፵፷፸፻ ፹፼፵፾ ፺፷፷ ፸፹ ፸ ᎎᎬᎩᎰᎫᎬᎴ ᎚ᎾᎰᎻᏁᎬᎹᎳᎨᎵᎫ ፸ᎀ፽፿ ፸፸፺ ᎀ ፷፵፼ ፷፵፷፹፸ ፸፿፵፷ ፸፼ ፾፷ ፸ ᎝ᎬᎹᎩᎶᎰᎺ ᎚ᎾᎰᎻᏁᎬᎹᎳᎨᎵᎫ ፸ᎀ፻፺ ፺፹ ፸፼ ፷፵፺፺ ፷፵፷፷፸፻፻ ፻፼፵፼ ፽፷፷ ፺፷ ፺ ᎉᎨᎹᎬᎵᎩᎼᎹᎮ ᎚ᎾᎰᎻᏁᎬᎹᎳᎨᎵᎫ ፸ᎀ፽፷ ፽፻ ፸፵፾ ፷፵፷፹ ፷፵፷፷፷፻፾፺ ፿፼፵፷ ᎀ፷ ፹፷ ፼ ᎐ᎵᎵᎬᎹᎭᎬᎹᎹᎬᎹᎨ ᎚ᎾᎰᎻᏁᎬᎹᎳᎨᎵᎫ ፸ᎀ፽፸ ፹፿ ፷፵፹፺ ፷፵፷፷፿ ፷፵፷፷፷፸፿ ፹፿፵፿ ፿፷ ፸፹ ፼ ᎎᎬᎵᎰᎺᎺᎰᎨᎻ ᎍᎹᎨᎵᎪᎬ ፸ᎀ፻፿ ፸፷፻ ፼፺ ፷፵፾፺ ፷፵፷፷፻፽፾ ፾፹፵፽ ፽፷፷ ፺፽ ፺ Dashidaira dam (1985) H=76.7m, V=9 MCM ᎉᎨᎰᎹᎨ ᎐ᎵᎫᎰᎨ ፸ᎀ፿፸ ፼፸ ᎀ፵፽ ፷፵፺ ፷፵፷፷፻፿ᎀ ፺፹፵፷ ᎀ፷ ፻፷ ፸ ᎎᎴᎼᎵᎫ ᎈᎼᎺᎻᎹᎰᎨ ፸ᎀ፻፼ ፺፾ ፷፵ᎀ፺ ፷፵፷፾ ፷፵፷፷፻፽፼ ፸፺፵፺ ፽ ፸፽፿ ᎕፵ᎈ፵ ᎏᎬᎵᎮᎺᎯᎨᎵᯢᯙ ᎊᎯᎰᎵᎨ ፸ᎀ፽፽ ፽፼ ፸፺፵፺ ፸፵፸፿ ፷፵፿፻፹ ፸፸፵፺ ፹ ፽፾፹ ፹ᰮ፺ ᎚ᎨᎵᎻᎶ፧ᎋᎶᎴᎰᎵᎮᎶ ᎝ᎬᎵᎬᏁᎼᎬᎳᎨ ፸ᎀ፾፻ ፻፾ ፺ ፷፵፷፿ ፷፵፷፷፽፽፾ ፺፾፵፼ ፼ ፾፹ ᎕፵ᎈ፵ ᎑ᎬᎵ፴ᎺᎯᎨᎵ፴ᎷᎬᎰᯢᯙ ᎛ᎨᎰᎾᎨᎵ ፸ᎀ፺፿ ፺፷ ፾ ፷፵፹፺ ᎕፵ᎈ፵ ፺፷፵፻ ፸፹፵፹ ፸፹፾፹ ፸ ᎎᎼᎨᎵᎻᎰᎵᎮ ᎊᎯᎰᎵᎨ ፸ᎀ፼፺ ፻፺ ፹፹፾፷ ፽፷ ፸፵፼ ፺፾፵፿ ፿፷ ፸፹፷ ᎕፵ᎈ፵ ᎎᎼᎬᎹᎵᎺᎬᏀ ᎜᎚ᎈ ፸ᎀ፹፾ ፹፿፵፽ ᎀ፸ ፸፵፾ ፷፵፷፻፺፺ ፼፺፵፼ ፸፹፼ ፸፹፷ ᎕፵ᎈ፵ ᎏᎬᎰᎺᎶᎵᎮᎳᎰᎵ ᎊᎯᎰᎵᎨ ፸ᎀ፼ᎀ ፺፷ ፿፵፽ ፷፵፾ ፷፵፽ ፸፹፵፺ ፷፵፿ ፾፹ ᎕፵ᎈ፵ ᎐ᎪᎯᎨᎹᎰ ᎐ᎵᎫᎰᎨ ፸ᎀ፾፼ ፺፽፵፿ ፸፸፵፽ ፼፵፾ ፷፵፷፷፹፸፿ ፹፵፷ ፹፵፸፽ ፹፻ ᎕፵ᎈ፵ ᯢᯙ H=185m ᎖ᎼᎪᎯᎰ፴᎒ᎼᎹᎮᎨᎵ ᎍᎶᎹᎴᎬᎹ፧᎜᎚᎚᎙ ፸ᎀ፽፸ ፺፼ ፼፽ ፸፺ ፷፵፷፷፺፾፽ ፻፵፺ ፸፷፷፷ ፹፻፷፷ ᎕፵ᎈ፵ ᎚ᎨᎵᎴᎬᎵᎿᎰᎨᯢᯙ ᎊᎯᎰᎵᎨ ፸ᎀ፽፷ ፻፼ ᎀ፽፻፷ ፸፽፷፷ ፷፵፹፹፻ ፽፵፷ ፹፷፷፷ ፹ᎀ፷፷ ᎕፵ᎈ፵ ᎚ᎬᎭᎰᎫ፴᎙ᎼᎫᯢᯙ ᎐ᎹᎨᎵ ፸ᎀ፽፹ ፿፹ ፸፾፽፷ ፼፷ ፷፵፺፼፹ ፺፼፵፹ ፸፷፷ ፹ᎀ፷፷ ᎕፵ᎈ፵ ᎚ᎯᎼᎰᎪᎨᎶᏁᎰ ᎊᎯᎰᎵᎨ ፸ᎀ፼፿ ፹፿ ᎀ፵፽ ፷፵፽፺ ፷፵፷፸፿፽ ፸፼፵፹ ፼፷ ፺፽ ᎕፵ᎈ፵ High mountains >3000m Unazuki dam (2001) H=97m, V= 24.7 MCM ᯡᯙᎈᎽᎬᎹᎨᎮᎬ፧ᎨᎭᎻᎬᎹ፧ᎫᎨᎴ፧ᎪᎶᎴᎷᎳᎬᎻᎰᎶᎵᯜ᫝᫝ᯢᯙ᎚ᎳᎼᎰᎪᎰᎵᎮ፧ᎫᎨᎴᎺ

Application of Sediment Flushing from the view point of water use Coordinated sediment flushing in Kurobe river

፸፷፷፷፷፷ ᡢ ፧ ᎔ᎬᎺᎯᎰᎨᎵ 'DVKLGDLUD (/ ፧ ᎚ᎬᎫᎰᎴᎬᎵᎻ፧ᎍᎳᎼᎺᎯᎰᎵᎮ፧ᎫᎨᎴᎺ ᎋᎶᎵᎮᎱᎰᎨᎵᎮ ᡣ ᡤ ፸፷፷፷፷ ᎟ᎰᎵᎨᎵᎱᎰᎨᎵᎮ ᔽᯭ፹፵፻፼ᏽ፸፷፺ 7ุKUV ᎚ᎼᎪᎪᎬᎺᎺ ᎍᎨᎰᎳᎼᎹᎬ ᎍᎬᎵᎮᎴᎨᎵ ᎚ᎯᎨᎵᎮ፧ᏀᎶᏀ፧ᎱᎰᎨᎵᎮ ᎉᎨᎰᎳᎰᎨᎵᎯᎬ KU KU KU KU ᎈᎺᎾᎨᎵ 29hrKU ᎡᎯᎨᎿᎰ KU ᡢ ᡥ ፸፷፷፷ Flushing 53hr ᎚ᎯᎼᎰᎲᎶᎼ ᎏᎶᎶᎽᎬᎹ 8QD]XNL ᎔ᎈ᎚ ᎏᎼᎨᎵᎻᎨᎵᎲᎶᎼ ᎋᎨᎯᎼᎶᎭᎨᎵ ᡦ ᎞ᎼᎸᎰᎨᎵᎮᎿᎰ ᎒ᎼᎹᎶᎩᎬ ᡥ፧ᎌ᎓፵፹፺፼Ꮄ ᯟ ᎏᎼᎨᎵᎮᎳᎨᎵᎮᎻᎨᎵ ᎉᎶᎼᎳᎫᎬᎹ ᡣ (/ ᎚ᎨᎲᎼᎴᎨ ᡤ ᡣ ᎍᎼᎪᎯᎼᎵᎱᎰᎨᎵᎮ ᎔ᎨᎵᎮᎳᎨ ᎋᎨᎵᎱᎰᎨᎵᎲᎶ ᎎᎨᎵᎮᎵᎨᎵ ᎌᎳᎬᎷᎯᎨᎵᎻ፧ᎉᎼᎻᎻᎬ ፸፷፷ ᎎᎬᎵᎰᎺᎺᎰᎨᎻ ᎍᎬᎵᎮᎱᎰᎨᎺᎯᎨᎵ ᎊᎈ᎗ ᎛ᎯᎹᎬᎬ፧ᎎᎶᎹᎮᎬᎺ ᎎᎼᎬᎹᎵᎺᎬᏀ ᎛ᎨᎹᎩᎬᎳᎨ ᎉᎨᎰᎹᎨ ᎓ᎰᎼᎱᎰᎨᎿᎰᎨ ᎎᎼᎨᎵᎻᎰᎵᎮ ᎝ᎬᎹᎩᎶᎰᎺ ᎈᎴᎨᎳᎨᏁᎨ ᎚ᎬᎭᎰᎫ፴᎙ᎼᎫ ᎟ᎰᎴᎨᎳᎰᎵ ᎚ᎨᎵᎻᎶ፧ᎋᎶᎴᎰᎵᎮᎶ ᎓ᎨᎮᎶ፧ᎳᎶᎰᏁᎨ ᎜ᎵᎨᏁᎼᎲᎰ ᎎᎬᎩᎰᎫᎬᎴ ᎏᎬᎰᎺᎶᎵᎮᎳᎰᎵ ᎍᎬᎵᎯᎬ KU KU KU KU ᡤ ᡦ ᎉᎰᎲᎶᎼ ᎏᎶᎵᎮᎳᎰᎵᎮᎱᎰ ᡢ ᡣ ᡤKU ᡥ ᡦ ᎙ᎶᎪᎲ፧ᎊᎹᎬᎬᎲ ᎋᎨᎺᎯᎰᎫᎨᎰᎹᎨ ᎏᎬᎵᎮᎺᎯᎨᎵ ᎟ᎰᎵᎸᎰᎨᎶ ᎚ᎼᎰᎪᎨᎶᏁᎰ ᎚ᎯᎰᎴᎨᎵ ᎉᎨᏁᎱᎨᏁᎼᎰ 44hr K ፸፷ ᎎᎴᎼᎵᎫ ᎎᎶᎵᎮᏁᎼᎰ ᎚ᎨᎵᎴᎬᎵᎿᎰᎨ ᎟ᎰᎨᎶᎳᎨᎵᎮᎨᎰ 68hr ᎡᎯᎰᏀᎼ ᎖ᎼᎪᎯᎰ፴᎒ᎼᎹᎮᎨᎵ ᎞ᎨᎹᎺᎨᎲ ᎘ᎰᎵᎮᎻᎶᎵᎮᎿᎰᎨ ᎡᎯᎬᎵᏁᎰᎳᎰᎨᎵᎮ ᎐ᎪᎯᎨᎹᎰ ᎠᎨᎵᎮᎼᎶᎿᎰᎨ ᎍᎰᎹᎺᎻ፧ᎍᎨᎳᎳᎺ ᎞ᎬᎳᎳᎩᎬᎫᎨᎪᎯᎻ Sediment flushing rule by the river committee: ፸ ፷፵፷፷፸ ፷፵፷፸ ፷፵፸ ፸ ፸፷ During rainy season from June to July 3 ᎊᎈ᎗ᯟ᎔ᎈ᎙ Timing of natural floods exceed discharges 300m /s

CrossVŏ้ sectionPô1

፻፷፷ Sedimentation volume Elevation400 (m) Sedimentation volume 380፺፿፷ change in Dashidaira dam 2004 2004 ϕΏ༙͊ Sedimentation ፺፽፷ ᡫ Side bank Sedimentation 360 BF ᡪ AF 1995ᡩ ᡤ erosion ፺፻፷ 340 Degradationǉ̀ȵ profiles ᡥ ᡢ 320፺፹፷ ᡧ ᡦ ᡨ 300፺፷፷ Original bed 1994 1985 280፹፿፷ ፴፼፷፷ ፴፷ ፼፷፷ ፸፳፷፷፷ ፸፳፼፷፷ ፹፳፷፷፷ ፹፳፼፷፷ ፺፳፷፷፷ 0 500 1,000 1,500 2,000 2,500 3,000 :7 ᡣ Elevation97 (m) 9000 6 3 Gross storage: 9410 m ĳ 17204103 m3 7 8000 3 3 ዅ Ĵ 800410 m 87 2003 3 ᡪ m ᡭ ᏽ 3 3 Dashidaira dam 3 7000 280 10 m 7 The biggest flood in 1995 ᡤ 2004 ᡬAF 10 ķ 7004103 m3 ᡩ 4 6000 ዄ 4 3 3ዅ 7 3450 10 m Ĺ 4 3 3 ዄ 60 10 m ᡢ ᡥ 7 ᡧ ᡨ 5000 ᡦ ı 4 3 3 7 Original bed 80 10 m 4000 ᡫ 7 2004 BF 2001 3000 ĸ 5904103 m3 77 BF: Before flushing ;<777 ; <777 <777 <777 <777 <777 Ķ 3404103 m3 ϐW0 1,000 2,000 3,000 4,000 5,000 2000 Ĳ 204103 m3 ᡣ 3 3 Sedimentation Amount Amount Sedimentation ĵ 460410 m AF: After flushing 1000 İ 4604103 m3 ĺ 904103 m3

0 '96 '97 '98 '99 '00 '01 '02 '03 '85 '86 '87 '88 '89 '90 '91 '92 '93 '94 ‘04

Unazuki dam '95.6 '95.7 '95.11

䋭㩷㪈㪌㪍㩷䋭 4 Subjects of sediment flushing Total water use and flushed sediment volume in sediment flushing dams Flushing efficiency ፸፷፷፷፷ Flushing efficiency ᎋᎨᎺᎯᎰᎫᎨᎰᎹᎨ᫝ ᯙ =scoured sediment volume / water use ፺ ᎝ᎬᎹᎩᎶᎰᎺ Ꮄ ᎍᎬᎄ፷፵፸ ፺ ᎎᎬᎩᎰᎫᎬᎴ ᎍᎬᎄ፷፵፷፼ ᎉᎨᎰᎹᎨ Flushing effect ᎍᎬᎄ፷፵፷፹ = scoured sediment volume / total deposited 95 sediment volume before flushing ፸፷፷፷ 99 96

01 Environmental impacts 98 97 ᰮ ᎍᎬᎄ፷፵፷፸ the influences of SS rising and DO dropping - 04

duration time etc. SS: Suspended solid concentration 03

DO: Dissolved oxygen ᎛ᎶᎻᎨᎳ፧ᎍᎳᎼᎺᎯᎬᎫ፧᎚ᎬᎫᎰᎴᎬᎵᎻ፧᎝ᎶᎳᎼᎴᎬᯘ᎚ᯙᯘ፸፷ 02 ፸፷፷ ፸፵፷ ፸፷፵፷ ፸፷፷፵፷ Study on sediment discharge process during flushing ᎛ᎶᎻᎨᎳ፧᎞ᎨᎻᎬᎹ፧᎝ᎶᎳᎼᎴᎬᯘ᎞ᯙᯘ፸፷፽Ꮄ፺ᯙ operations from quantity and quality point of view is

very important. Fe: Flushing efficiency =Total flushed sediment volume/ Total water volume

Environmental monitoring during sediment flushing Flushing efficiency of Sediment flushing dams Sea Water quality N -250 ᎚ᎯᎼᎰᎪᎨᎶᏁᎰ (DO, SS etc.) -150 ᎚ᎬᎭᎰᎫ፴᎙ᎼᎫ Mud quality -50 ᎑ ᎬᎵ፴Ꮊ ᎯᎨᎵ፴ᎷᎬᎰ Aquatic species ᎚ᎨᎵᎻᎶ፧ᎋᎶᎴᎰ ᎵᎮ Ꮆ Cross sections ᎍᎬᎹᎹᎬᎹᎨ Shimokurobe ᎉᎨᎹᎬᎵᎩᎼᎹᎮ 0 5 10 km River ᎉᎨᎰᎹᎨ Water quality ᎝ᎬᎹᎩᎶᎰ Ꮊ (DO, SS etc.) ᎎᎬᎩᎰ ᎫᎬᎴ Mud quality Unazuki dam Aquatic species ᎋᎨᎺ ᎯᎰ ᎫᎨᎰ ᎹᎨ᫝ Cross sections ፷ ፷፵፷፼ ፷፵፸ ፷፵፸፼ ፷፵፹ Dashidaira dam Reservoir ᎍᎳᎼᎺᎯᎰᎵᎮ፧ᎬᎭᎭᎰᎪᎰᎬᎵᎪᏀ᫝ᎍᎬ Water quality (DO, SS etc.) F : Flushing efficiency =Total flushed sediment volume/ Total water volume Mud quality e Cross sections

፷ ፼ ፸፷ Average hourly ፸፼ ᎈᎽᎬᎹᎨᎮᎬ፧ᎯᎶᎼᎹᎳᏀ፧ᎹᎨᎰᎵᎭᎨᎳᎳ፧ᎰᎵ፧ᎋᎨᎺᎯᎰᎫᎨᎰᎹᎨ፧ᎩᎨᎺᎰᎵ፧ᎢᎴᎴᎤ ፹፷ rainfall (mm) Measurement values of DO and SS during flushing ፹፼ Amount of DOዄmg/lዅ SSዄmg/lዅ ፸፳፹፷፷ ᎐ᎵᎭᎳᎶᎾ፧ᎫᎰᎺᎪᎯᎨᎹᎮᎬ፧ᎢᎴ፺፶ᰣᎤ ፺፻፼ ዄ ዄ ዅ ᎖ᎼᎻᎭᎳᎶᎾ፧ᎫᎰᎺᎪᎯᎨᎹᎮᎬ፧ᎢᎴ፺፶ᰣᎤ ፺፻፷ Sediment flushing Dashidaira Minimum value) Maximum value ፸፳፷፷፷ ᎞ᎨᎻᎬᎹ፧ᎳᎬᎽᎬᎳ፧ᎢᎴᎤ ፺፺፼ sediment Shimo- Shimo- Dashidaira Unazuki Dashidaira Unazuki ፿፷፷ ፺፺፷ Water level Year Event flushing kurobe kurobe Discharge ፺፹፼ ፽፷፷ Jul-95 Flood ᯝᯝ11.3 10.5 ᯝ 3,700 1,800 ፺፹፷ (EL.m) (m3/s) Oct-95 Flushing 1.72MCM 8.8 9.7 8.9 103,500 29,400 26,000 ፻፷፷ ፺፸፼ ፺፸፷ Jun-96 Flushing 0.8MCM 10.7 10.3 9.8 56,800 9,470 6,770 ፹፷፷ ፺፷፼ Jul-97 Flushing 0.46MCM 9.8 9.2 9.3 93,200 28,900 4,330 ፷ ፺፷፷ Jun-98 Flushing 0.34MCM 8.2 7.0 7.3 44,700 9,400 6,750 ፸፳፽፷፷ ᎐ᎵᎭᎳᎶᎾ፧ᎫᎰᎺᎪᎯᎨᎹᎮᎬ፧ᎢᎴ፺፶ᰣᎤ ፹፼፼ Jul-98 Flood ᯝᯝ10.5 9.5 ᯝ 6,090 5,260 ፸፳፻፷፷ ᎖ᎼᎻᎭᎳᎶᎾ፧ᎫᎰᎺᎪᎯᎨᎹᎮᎬ፧ᎢᎴ፺፶ᰣᎤ ፹፼፷ Sep-99 Flushing 0.7MCM 6.0 5.8 6.5 161,000 52,100 25,700 Discharge ᎞ᎨᎻᎬᎹ፧ᎳᎬᎽᎬᎳ፧ᎢᎴᎤ ፸፳፹፷፷ ፹፻፼ Coordinated Water level Jun-01 0.59MCM 7.2 11.4 10.2 90,000 2,500 1,500 (m3/s) ፸፳፷፷፷ ፹፻፷ flushing ፿፷፷ ፹፺፼ (EL.m) Coordinated Jul-01 ዉ 11.1 10.6 9.6 29,000 3,700 2,200 ፽፷፷ ፹፺፷ sluicing ፻፷፷ ፹፹፼ Coordinated Jul-02 0.06MCM 9.5 10.5 9.5 22,000 5,400 2,800 ፹፷፷ ፹፹፷ flushing ፷ ፹፸፼ Coordinated 11.8 11.3 9.6 69,000 17,000 10,000 ፸፷፷፳፷፷፷ Jun-03 flushing 0.09MCM ᰃᰃᯘᎋᎨᎺᎯᎰᎫᎨᎰᎹᎨ፧ᎫᎨᎴᯙ፧ᎢᎴᎮ፶ᎳᎤ Coordinated Jul-04 0.28MCM ᰃᰃᯘ᎜ᎵᎨᏁᎼᎲᎰ፧ᎫᎨᎴᯙ፧ᎢᎴᎮ፶ᎳᎤ flushing 9.3 10.2 9.8 42,000 6,800 11,000 ᰃᰃᯘ᎚ᎯᎰᎴᎶᎲᎼᎹᎶᎩᎬᯙ፧ᎢᎴᎮ፶ᎳᎤ SS ፸፷፳፷፷፷ Jul-04 Flood ᯝ 10.8 11.2 10.3 30,000 12,000 14,000 Coordinated ᯝ (mg/l) Sediment Jul-04 sluicing 10.6 11.2 9.6 16,000 17,000 21,000 ፸፳፷፷፷ flushing in July 2004 Manual sampling in every one hour ፸፷፷ ፸፹ ፸፿ ፷ ፽ ፸፹ ፸፿ ፷ ፽ ፸፹ ፸፿ ፷ ፽ ፸፹ ፸፿ ፷ ፽ ፸፹ Continuous monitoring method for DO and SS is necessary 2004/7/16 7/17 7/18 7/19 7/20 Development of new techniques for high SS monitoring

䋭㩷㪈㪌㪎㩷䋭 5 Balancing of Flushing efficiency and environmental Promotion strategy of reservoir sediment impacts management

A) Priority evaluation of reservoirs where sediment management should be introduced

Flushing naturally = Much water Flushing efficiently = Little water B) Appropriate selection of reservoir sediment Low sediment management strategy High sediment concentration management strategy concentration C) Development of efficient and environmentally Reservoir draw down compatible sediment management techniques Water use Enough flushing discharge water Rinsing discharge after flushing, etc.

A) Priority evaluation of reservoirs where sediment B) Appropriate selection of reservoir sediment management should be introduced management strategy

፸Ƃʇ ᎖Ꮀ ᎋ፳፧᎚᎗ ᎊᎨᎷᎨᎪᎰᎻᏀ፴ᎰᎵᎭᎳᎶᎾ፧ᎹᎨᎻᎰᎶ፧ᎨᎵᎫ፧᎙ᎬᎺᎬᎹᎽᎶᎰᎹ፧᎓ᎰᎭᎬ ፹Ǫ໑ ᎚ᎬᎵᏁᎼ ᎚ᎎ ፺Ƿ൲ ᎠᎨᎺᎼᎶᎲᎨ ᎚ᎎ፳፧ᎋ፳፧᎗ᎍ Reservoir sustainability factor ፻ Ȩ¾ ᎒ᎨᎺᎨᎮᎰ ᎚ᎎ፳፧᎗ᎍ CAP/MAS<100yrs, ፸፷፷፷፷፷ ፼Ƃശ ᎖ᎶᎴᎨ ᎚ᎎ፳፧᎗ᎍ No measures (from inner factors) ፽iΚ ᎛ᎶᎲᎰᎾᎨ ᎚ᎎ - Reservoir life = CAP/MAS 7% ᎊᎯᎬᎪᎲ፧ᎫᎨᎴ ፾ȳȮ ᎔ᎰᎼᎹᎨ ᎚᎗ ፿Ϳ ᎏᎰᎹᎨᎶᎲᎨ ᎋ፳፧᎗ᎍ ᎍᎳᎼᎺᎯᎰᎵᎮ ᎀ̂ɝശ᎚ᎨᎲᎼᎴᎨ ᎋ CAP/MAS ፸፷ ɝ˂ ᎏᎨᎲᎼᎾᎨ ᎌ፳፧ᎋ ፸፷፷፷፷ ᎚ᎪᎶᎹᎰᎵᎮ፧ᎮᎨᎻᎬ ፸፸ ʇ1 ᎐ᎲᎨᎾᎨ ᎚᎗፳፧ᎌ፳፧ᎋ፳፧᎗ᎍ <1000yrs, ፸፹ ͪɕ ᎠᎨᎴᎨᎮᎼᎪᎯᎰ ᎚ᎎ፳፧᎗ᎍ Comprehensive sediment ᎚ᎪᎶᎹᎰᎵᎮ፧ᎷᎰᎷᎬ ፸፺ Œ΢ ᎈᎲᎰᎩᎨ ᎌ፳፧ᎋ፳፧᎗ᎍ 34% CAP/MAS=100 ፸፻ Ô˂᎔ᎰᎾᎨᎉ፳፧ᎌ፳፧ᎋ፳፧ᎊᎋ management factor ᎉᏀᎷᎨᎺᎺᎰᎵᎮ ፸፼ Ù͈ ᎔ᎨᎲᎰᎶ ᎌ፳፧ᎋ፳፧ᎊᎋ -500yrs, 34% ፸፷፷፷ ፸፽ ̪ʎ ᎒ᎶᎺᎯᎰᎩᎼ ᎌ፳፧ᎊᎋ ᎌᎿᎪᎨᎽᎨᎻᎰᎵᎮ ᡳ ፸፾ ʋ1 ᎔ᎨᎻᎺᎼᎲᎨᎾᎨ ᎉ፳፧ᎌ፳፧ᎊᎋ - impacts to the downstream ᡨ ፸፿ Ź ᎈᎺᎨᎯᎰ ᎉ ᡫ ᎋᎹᎬᎫᎮᎰᎵᎮ ፸ᎀ üᬊ ᎋᎨᎺᎯᎰᎫᎨᎰᎹᎨ ᎍ ᡰ river and an actual ᡧ ᡥ ፹፷ ʽƙȼ ᎜ᎵᎨᏁᎼᎲᎰ ᎍ ᡯ ᡬ ᡢ ᡪ ᡱSediment check dam, environmental deterioration ᎙ᎬᎺᎬᎹᎽᎶᎰᎹ፧᎓ᎰᎭᎬᎄᎊᎈ᎗፶᎔ᎈ᎚ ፸፷፷ ᡮ ᡣ ᡲ Sediment replenishment ᎊᎋ፧ ᯪ᫝ᎊᎯᎬᎪᎲ፧ᎫᎨᎴ CAP/MAS= ᡦ ᎍ፧ ᯪ᫝ᎍᎳᎼᎺᎯᎰᎵᎮ፧፯ᎋᎹᎨᎾ፧ᎫᎶᎾᎵ፰ ᡭ ᡤ ᡩ degree 500-1000yrs, 25% ᡵ Sediment bypass, Sluicing ᎗ᎍ ᯪ᫝ᎍᎳᎼᎺᎯᎰᎵᎮ፧፯᎗ᎨᎹᎻᎰᎨᎳ፧ᎫᎹᎨᎾ፧ᎫᎶᎾᎵ፰ ᡴ ᎚ᎎ ᯪ᫝᎚ᎪᎶᎹᎰᎵᎮ፧ᎮᎨᎻᎬ Sediment flushing, Sediment scoring gate ᎚᎗ ᯪ᫝᎚ᎪᎶᎹᎰᎵᎮ፧ᎷᎰᎷᎬ ፸፷ ᎉ ᯪ᫝ᎉᏀᎷᎨᎺᎺᎰᎵᎮ ፷፵፷፷፸ ፷፵፷፸ ፷፵፸ ፸ ፸፷ ᎌ ᯪ᫝ᎌᎿᎪᎨᎽᎨᎻᎰᎵᎮ Technical difficulty factor Reservoir lives (CAP/MAS) of ᎋ ᯪ᫝ᎋᎹᎬᎫᎮᎰᎵᎮ multipurpose dams in Japan ᎊᎨᎷᎨᎪᎰᎻᏀ፴ᎰᎵᎭᎳᎶᎾ፧ᎹᎨᎻᎰᎶᎄᎊᎈ᎗፶᎔ᎈ᎙

C) Development of efficient and environmentally Sediment property and recycling compatible sediment management techniques

ȡV ᭑᭔᭮᭢ᮐWashload+Suspendedᮘᮧ᭴ᯛȳ੶V load Bedȳ੶V load+Suspendedᯛ ȡV load Bed load Sediment᭫ᮋ replenishmentç̅ ȳ੶V Suspendedᯘ᭑᭔᭮᭢ᮐ load ᯘİૡForeØƥ set bed͠ᯙ Wash ᮘᮧload᭴ᯙ "Take", "Transport" and "Discharge" ᯘBottom¡ૡØƥ set͠ bedᯙ ᯘາૡTop Øƥset bed͠ᯙ ᎏ፵᎞፵᎓ Sediment recycling for Flood discharge ØVᬡDeltaŻ construction materials and so on - Sediment flushing/sluicing and sediment bypassing ᎓፵᎞፵᎓ ᯘ᭑᭔᭮᭢ᮐWashloadᮘᮧ᭴ᯙ Downstream should be introduced more. ȵȡૡ Recycling feasible area Delta᭲ᮖ᭪ Middleɋȡૡ area Upstreamȴȡૡ area - The sediment trucking and supply, and the Recycling Hydro-suction Sediment Removal System (HSRS) are infeasible OSizeࢠǡą ̔OᮦClay,᭢ᮖ silt᭳ɕ̅ MainlyVɕ ̅sand SandíᮦV andɕ gravel̅ needs to be improved furthermore and introduced as Graink͛ᬝ size Gravel=0,íᎄ፷᫞Vᎄ፸፷ ᫞ Gravel=10,íᎄ፸፷᫞Vᯭ ፻፼᫞ Gravel=30,íᎄ፺፷᫞Vᯭ ፻፷᫞ ̐ªąK Sand=10,̔Oᯭ ፼፷᫞ Sand=45,̔Oᯭ ፺፷᫞ Sand=40,̔Oᯭ ፹፷᫞ content(%)ᯘǹ˿ᯪ፬ᯙ Clay=50,᭢ᮖ᭳ᯭ Silt=40፻፷ Clay=30,᭢ᮖ᭳ᯭ Silt=15፸፼ Clay=20,᭢ᮖ᭳ᯭ Silt=10፸፷ supplementary measures. Ø V Fine;̐ąᎍᎪ sediment ᎍᎪᎄᎀ፷፬ʿȴFc=over90% ᎍᎪᎄ፻፼ᰮ፼፷፬Fc=45-50%ŷ ª Fc=lower30%ᎍᎪᎄ፺፷፬ʿȵ ǀ ā ȴ<ʅWater contentŻŏᰧ Ꮎᎄ፸፷፷፬ʿȴw=over100% Ꮎᎄ፼፷ᰮ፽፷፬w=50-60%ŷ ª w=lower40%Ꮎᎄ፻፷፬ʿȵ Density,˲ªᮦശ෇ Porosityŏ ̪Small᫝᫝᫝᫝᫝᫝᫝᫝᫝ ᜐᜒ᫝᫝᫝᫝᫝᫝᫝᫝᫝᫝᫝᫝᫝ƂLarge Ignitionĕrʓ୲᎐Ꭾ loss Ig=over10%᎐Ꭾᎄ፸፷፬ŷª ᎐Ꭾᎄ፿፬Ig=ca.8%ŷª ᎐Ꭾᎄ፻፬Ig=ca.4%ŷª Sediment property ȽwNutrientsÛᮦ˥༳Ď LargeƂ᫝᫝᫝᫝᫝᫝᫝᫝᫝ ᜐᜒ᫝᫝᫝᫝᫝᫝᫝᫝᫝᫝᫝᫝Small̪

䋭㩷㪈㪌㪏㩷䋭 6 HSRS (Hydro-suction Sediment Removal System) Conclusion Current status of reservoir sedimentation in Japan are ; total sedimentation loss is 7.4%; annual loss is 0.24%/yr. Fixed type HYDRO PIPE - Vortex tube Reservoir sediment management is important from the view - Hydro pipe points of reservoir safety, sustainability and the - Multi-hole suction comprehensive management of sediment routing system. sediment removable Bypassing is suitable for sediment management of existing system MULTI HOLE SUCTION SEDIMENT dams. REMOVABLE SYSTEM Movable type Flushing is effective and ‘Flushing efficiency’, ‘Flushing effect’ - Hydro J and ‘Environmental impacts’ of sediment flushing are to be - SY system studied more and it is important to cause them a balance. Promotion strategy of reservoir sediment management should SY SYSTEM be established by the following points; HYDRO J - Priority evaluation of reservoirs where sediment management should be introduced - Appropriate selection of reservoir sediment management strategy - Development of efficient and environmentally compatible sediment management techniques.

Kurobe alluvial fan

Sediment discharge from Unazuki dam

Thank you for your attention!

䋭㩷㪈㪌㪐㩷䋭 7