May 9-12
Kyoto-Japan2017

2nd International Workshop on

Organizers

Sediment Bypass Tunnels

Closing Remarks

Co-organizers

Sponsors

NaganoPrefecture

Tetsuya SUMI
Disaster Prevention Research Institute, Kyoto University

Session1(SBTsintheworld)

Pressure fluctuation

Diversion weir,Gate operation etc.
Session2(Predictingand
controllingsediment
inupstreamriverandreservoirs)

Upstream

Sediment
deposition, clogging

Abrasion

Riverbed morphology,
water quality, Ecology etc.

Session3 (TunnelͲ hydraulics,invertabrasion)

Session5 (DownstreamaspectsͲmorphologicalandecologicaleffects)

Session4 (Bedloadmonitoring)

Session6 (Operation/EIA)

TunnelDownstream• Three SBTs have been installed in Kobe more than 100 years ago for
sediment passage and clear water storage.
• Sediment bypass system is containing both tunnel and open channel.
(Indonesia)• Suspended high concentration fine sediment can be vented and diverted
by sluicing tunnels. (Taiwan)• Several methodologies to increase the tunnel performance are introduced.
– Combination with rainfall-runoff prediction (Asahi)– Sediment excavation and placing up/downstream SBTs during nonflooding time (Miwa, Shihmen)• High velocity flow, sediment transport and abrasion models have been
updated and calibrated by field data.
• Tunnel curvature and abrasion effects have been discussed by model andfield data.

••
•
•
•

Several bed load monitoring systems have revealed spatio-temporal sedimenttransport variation which will be useful to understand the abrasion mechanismand propose countermeasures.
We should discuss which sensor will be suitable based on target grain size,
sediment transport rate as well as target velocity.
Positive effects of SBTs can be evaluated by sediment budget, downstream
riverbed changes and aquatic lives such as invertebrates.
Various new methodologies are very much welcome such as Metabarcording
approach in order to evaluate environmental effects.
New SBTs are now in monitoring stages which will show good performances andthe monitoring guidelines should be prepared soon. (Solis, Koshibu, Matsukawa)Keyquestions: HowtofindsuitableexistingdamsforSBTs?
HowtoapplySBTfornewdams?(Sambor damintheMekongRiver)(KeymessagebyProf.G.Annandale)

TachigahataDam(1905)

JapanAsahi(1998)
Miwa(2005)

NunobikiDam(1908)

Koshibu(2016)

MukoͲnoͲike(1916)

Matsukawa(2016)

Pfaffensprung(1922)

Runcahez(1962)
Egshi(1976)

Switzerland

Palagnedra(1977)

Rempen(1986)
Solis(2012)

Sediment management to minimize aggradationin reservoirs is achieved with a variety oftechniques categorized in three main strategies(ICOLD 1989, 1999, 2009, Morris & Fan 1998,
Kantoush & Sumi 2010, Annandale 2011, 2013,
Kondolf et al. 2014, Auel et al. 2016).

Auel etal.2016••••

Inflow maximum sediment grain size is critically definedby upstream velocity and tractive force.
From deep reservoir, only fine sediment will betransported even in case of density current venting.
From upstream, both coarse and fine sediment can be
guided to the SBT.
From middle reach of reservoirs, normally only finesediment but coarse sediment can be transported withcombination of effective partial drawdown.

Pressureflow

Freeflowbypass

Submergedflowbypass(SluicingTunnel)

Tunneloropenchannel

BottomoutletSluicingTunnelFreeflowbypass

• Sluicing requires a partial water level drawdown to transport incoming
and to some extent accumulated sediments to the dam outlet structure,
whereas venting of turbidity density currents can be performed withoutlowering.
• Sluicing includes both bedload and suspended sediment, whereas venting isonly possible for the latter.

Two styles of Sediment bypass tunnels

Position A: Reservoir head

Source: Auel & Boes (2011)

Position B: Downstream of reservoir head

Bypass tunnel

WeirGradient 㸸1/34
Height 㸸3.8m
Width 㸸3.8m

Height 㸸13.5 m
Crest Length㸸45 m

Length : 2,350m
Max. discharge㸸140m3/s

OutletSBT Solis: Experiences
Sediment transport is sensitive to reservoir level• Ishibashi model (full set)
– Over estimate of abrasion volume and estimating too much
maintenance costs– Drawback for SBT• Ishibashi model (saltation part only) and Auelmodel
– More data for calibration– It is required to optimize project cost and hopefully increase
feasibility of SBTs• Collaboration with hydrological prediction of rainfall-runoff andsediment inflow– Optimize bypass operation with suitable gate operation– Solve conflict between water storage recovery for water user’s interest andbypassing high sediment-laden flow for minimizing sediment inflow to the mainreservoir• Combination with upstream and downstream dams, and othermethodologies in order to increase bypass efficiency– Additional water supply from upstream dams and/or local draw down
flushing– Combination with sediment replenishment upstream/downstream SBT andtrucking etc.

• Economic evaluation of SBT projects– How to select suitable long-term discounting rate
– How to estimate value of existing structures and value of extending their lives

Weather
forecast:
heavy
rain isexpectedStartmeasuringReservoir isdrawn down.
2. decision:
operation:
yes or no,start-time

1. decision:reservoir draw
down, mobilize
staff, inform key
persons: energy
trader, fishingauthorities, etc.

Gate opens,flushing
startsHigh inflow inreservoir.
Manipulations
at upstream
intakes
Inflow decrease,first discussion,
when to close.
3. decision:
When and how
to stop theoperation

30 h

18 h

15 h

12 h

0h- 0.5 h-3h

- 16 h- 30 hSBT Solis.
Operation 1/2Gatecloses.
«Afterflushing»over thedam. End ofoperation
Postoperationalworks,
documentation
Startfilling thereservoir

Reservoir level

Inflow

Sediment transport
Flow SBT

Flow Bottom outlets

30 h18 h

15 h

12 h0h- 0.5 h-3h

- 16 h- 30 hSBT Solis.
Operation 2/2

Storagerecovery
SBToperation

SBToperation

How to utilize upstreamhydrological data to optimize
bypass operation

Diversion Weir in Reservoir

Kurokawa
Miwa Dam¾ Rainfall and turbidity aremonitored by real-timebasis to predict inflow
discharge and sedimentconcentrationsBypass
Prediction ofDischarge andSedimentconcentration

Takaiwa
Sugishima¾ Effective bypass operationby using sedimentconcentration predictions

Mibu River

JFE-Alec
INFINITY-Turbi

How to effectively
divert suspended
sediment and highturbid flow through thetunnel• Suspended Sediment
Concentration (SSC)
measurement byTurbidity(INFINITYTurbiditymeter (JFEAdvantech Company))

30,000009/09 00:00

Suspended Sediment Concentration [mg/l]• 2D surface velocity
measurement by LargeScale Particle Image
Velocimetry (LSPIV)

500600500

Inflow (m3/s)
Senario A (Real) (m3/s)

25,000400

Senario B 䠄Qin=Qout䠅 (m3/s)
Inflow SS (mg/l)

20,000300

15,000200

10,000

100

5,000

0
09/06 12:00

Suspended Sediment
Concentration [mg/l]

Turbid flow monitoring

Inflow discharge [m 3/s]

600

09/07 00:00

09/07 12:00

09/08 00:00

09/08 12:00

30,00025,00020,00015,00010,000
5,000
00

100

200
300
400
Inflow discharge [m3/s]

Source:MLIT

Nagayasuguchi dam(MLIT)(Twoconveyerbeltswilltransport
excavatedsedimentfromonetributarytodownstream)

Sediment
Replenishment

conveyerbelt

Sakumadam(JͲPower/MLIT)(Bargeandconveyerbeltwilltransport
excavated/dredgedsedimentfrom
reservoirtodownstream)

Amahata Dam(Conveyingtunnel)

Barge
conveyerbelt26thCongress&86thAnnualMeeting,1Ͳ7July2018,Vienna(Austria)
Question100isnowcallforpapers.
1.

Best practice of storage design including sediment release structures, reservoir
operation and sedimentation management techniques including dredging,sediment removal and debris removal.
ሁ◁䜢ୗὶ䛻ὶ䛩タഛ䚸㈓Ỉụ᧯స䚸ཬ䜃䚸ὼ 䚸ሁ◁୪䜃䛻ṧ⁦㝖ཤ䜢ྵ䜐ሁ◁⟶⌮ᢏ⾡➼䛾᭱㐺䛺㈓Ỉụ㐠⏝ᡭἲ

2.

Sediment replenishment techniques downstream of dams for river regime andmorphology restoration.
Ἑᕝ䛾ὶἣཬ䜃⏕ែ⣔ಖ඲䛾䛯䜑䛾䝎䝮ୗὶ䜈䛾ᅵ◁౪⤥ᢏ⾡

3.

Experiences with turbidity current discharge by bottom outlets and theperformance of sediment bypass tunnels.
ᗏ㒊ᨺὶ⟶䛛䜙䛾⃮Ỉ䛾ᨺὶ⤒㦂䛸᤼◁䝞䜲䝟䝇䛾ᐇ⦼

4.

Effect of climate change on reservoir sedimentation and consequences onsustainable storage use.
Ẽೃኚື䛜ሁ◁䛸ᣢ⥆ྍ⬟䛺㈓Ỉụ౑⏝䛻୚䛘䜛ᙳ㡪• Suitable application environment (necessary inflow yield, reservoir
size, CAP/MAR-CAP/MAS ratio)– CAP: Reservoir capacity, MAR: Mean annual runoff volume, MAS: Mean annual sediment inflow••••

Typical SBT dimensions and hydraulic conditions
Sediment grain target size
SBT construction (incl. guiding structure, intake, tunnel, outlet)
Invert lining (abrasion-resistant materials: high-performance
concrete, steel, cast basalt, granite, Epoxy resin mortar)• Invert abrasion estimation and periodical maintenance works• Ecological impacts (sediment connectivity, downstream
morphological and ecological effects)• Case studies (Switzerland, Japan, Taiwan, ...)•Chair–•Member–––––––•

Mr. Nobuyuki Kuriki (Chubu Regional Management Bureau, MLIT)*Dr. Shuji Kimura (Chubu Regional Management Bureau, MLIT)
Mr. Kazushi Nakatsuka (Nagano Prefecture)*Mr. Hirotoshi Nishimoto (Nagano Prefecture)
Mr. Hajime Fukuroi (Kansai Electric Power Company, Inc.)
Mr. Noriaki Hakoishi (Japan Dam Engineering Center)
Mr. Atsushi Ishihara (Water Resources Environment Center)

Scientific member––•Prof. Tetsuya Sumi (Kyoto University)

Prof. Robert M. Boes (VAW, ETH Zurich, Switzerland)
Assoc. Prof. Jihn-Sung Lai (National Taiwan University, ROC)

Secretariat–––––––––––

Assoc. Prof. Sameh Kantoush (Kyoto University)
Assoc. Prof. Yasuhiro Takemon (Kyoto University)
Dr. Sohei Kobayashi (Kyoto University)
Dr. Christain Auel (ILF Consulting Engineers, Austria)
Mr. Masakuni Saiki (Chubu Regional Management Bureau, MLIT)
Mr. Satoshi Narusawa (Nagano Prefecture)
Mr. Hideaki Ohori (Water Resources Environment Center)
Mr. Yuichi Yamane (Kansai Electric Power Company, Inc.)
Assoc. Prof. Daizo Tsutsumi (Kyoto University)
Mr. Takahiro Koshiba (Kyoto University)
Mr. Toshiyuki Sakurai (Public Works Research Institute)Supported byㅰ㎡䠖䠄බ㈈䠅ி㒔ᗓி㒔ᩥ໬஺ὶ䝁䞁䝧䞁䝅䝵䞁䝡䝳䞊䝻䞊䠄୍㈈䠅㜵⅏◊✲༠఍䠄බ㈈䠅ி㒔኱Ꮫᩍ⫱◊✲᣺⯆㈈ᅋ
ி㒔኱Ꮫ㜵⅏◊✲ᡤ㸦≉ᐃ◊✲㞟఍㸧ओᘓタ⎔ቃ◊✲ᡤओᘓタᢏ⾡◊✲ᡤ኱ᡂᘓタओओᮾிᘓタࢥࣥࢧࣝࢱࣥࢺ
ओࢽ࣮ࣗࢪ࢙ࢵࢡ
ඵ༓௦࢚ࣥࢪࢽࣖࣜࣥࢢओओࣁ࢖ࢻࣟࢸࢵࢡ-)(࢔ࢻࣂࣥࢸࢵࢡओ• Special thanks to our staffs and Committee members– Dr. Sohei Kobayashi, Proceedings– Mrs. Chikako Morimoto, Registration– Mrs. Junko Ibaraki, Finance & Accommodation– Water Resources Environment Center , Proceedings– Chubu Regional Management Bureau, MLIT, Study tour
– Nagano Pref. Government, Study tour
– Kansai Electric Power Company, Welcome Reception– Mrs. Chizuko Muranaka, Interpretor