Dams in Japan Overview 2018

Tokuyama Dam

JAPAN COMMISSION ON LARGE DAMS

CONTENTS

Japan Commission on Large Dams History … …………………………………………………………………… 1 Operation … ………………………………………………………………… 1 Organization… ……………………………………………………………… 1 Membership… ……………………………………………………………… 1 Publication…………………………………………………………………… 2 Annual lecture meeting… …………………………………………………… 2 Contribution to ICOLD… …………………………………………………… 2

Dams in Japan Development of dams … …………………………………………………… 3 Major dams in Japan… ……………………………………………………… 4 Hydroelectric power plants in Japan… ……………………………………… 5 Dams completed in 2014 − 2016 in Japan … ……………………………… 6 Isawa Dam… ……………………………………………………………… 7 Kyogoku Dam … ………………………………………………………… 9 Kin Dam…………………………………………………………………… 11 Yubari-Shuparo Dam… …………………………………………………… 13 Tokunoshima Dam………………………………………………………… 15 Tsugaru Dam… …………………………………………………………… 17

Introduction to Dam Technologies in Japan Trapezoidal CSG dam … …………………………………………………… 19 Sediment bypass tunnel (SBT)… …………………………………………… 19 Preservation measures of dam reservoirs… ………………………………… 19 Advancement of flood control operation… ………………………………… 20 Dam Upgrading Vision… …………………………………………………… 21 Utilization of ICT in construction of dam… ………………………………… 22

Papers in ICOLD & Other Technical Publications Theme 1 Safety supervision and rehabilitation of existing dams…………… 23 Theme 2 New construction technology … ………………………………… 26 Theme 3 Flood, spillway and outlet works… ……………………………… 29 Theme 4 Earthquakes and dams… ………………………………………… 30 Theme 5 Reservoir sedimentation and sustainable development…………… 33 Theme 6 Geology and rock foundation……………………………………… 38 1 DAMS IN JAPAN - OVERVIEW 2018

Japan Commission on Large Dams

History Membership

In 1931, three years after the International Commission The members of JCOLD are incorporated bodies on Large Dams (ICOLD) was established, Japan joined involved in dam construction. They include government ICOLD as the Japan National Committee on Large Dams. bodies concerned with dam construction, electric power In 1944, Japan withdrew from ICOLD during the World companies, survey and research bodies, academic War II, then rejoined in March 1953. On September 13, associations, industrial associations, construction 1962, the Japan Commission on Large Dams (JCOLD) consultants, construction companies, and manufacturers (78 was established, and in January 2012, it became a General members as of January 2018). Incorporated Association.

Managing Director Operation General Vice Meeting President President(3) Senior Managing JCOLD is involved in operations such as surveys, research, Director international technology exchanges, etc. concerning large Auditor Advisor/ Directors dams and related facilities (below, “large dams”), in Counselor order to improve the design, construction, maintenance, and operation of large dams and to contribute to the Administrative Office development of the Japanese economy. Responsibilities include: Planning Committee

(1) Collection of information, surveying, and research (Sub Committees) Public Relations/ concerning large dams Environment Editorial (2) Exchange of technology and guidance concerning large dams Technical Committee

(3) Participation in ICOLD, assistance to its activities, and (Sub Committees) international exchange of technology concerning large International affairsa Dam Concrete Frost Damage Testing and Research dams Maximizing functions of existing dams Revision of current JCOLD technical guidelines (4) Dissemination of and spreading awareness of the achievements of surveys and research concerning large Figure-1 Organization Chart of JCOLD dams

(5) Other activities necessary to achieve the goals of JCOLD

In recent years, JCOLD has actively conducted a program of surveys and research on methods of harmonizing dam development with the environment and on ways to mitigate their environmental impacts to achieve the sustainable development of dams.

Organization

Under the leadership of the Chairman, there is a Planning Committee, Technical Committee, and Administrative Office. These committees undertake work in their respective areas. DAMS IN JAPAN - OVERVIEW 2018 2

Publication

JCOLD publishes its Journal, “Large Dams”, four times a year (January, April, July, October), which is distributed to members and subscribers. At ICOLD Congresses held once every three years, JCOLD publishes Current Activities on Dams in Japan in English, which introduces the state of dams and dam technologies in Japan, and distributes it to Congress participants (1997, 2000, 2003, 2006, 2009, 2012 and 2015).

Figure-3 Dam Technology Lecture and Discussion Meeting

Study Tour

To increase mutual awareness among engineers, including JCOLD members and others concerned with dams, on improving dam and hydroelectric power plant technologies and the construction of dams, JCOLD holds tours of dams and hydroelectric power plants still under construction with the cooperation of various organizations.

Figure-2 Publicaitons of JCOLD

Annual lecture meeting Figure-4 Tour of the site of the Hirase Dam (2017) Dam Technology Lectures and Discussion Meetings Contribution to ICOLD

(Held jointly with the Japan Association of Dam & Weir JCOLD submitted 357 ICOLD Congress papers until now. Equipment Engineering) In addition, Many Japanese engineers participate in ICOLD Annual Meeting and Congress. At the meeting, the results of surveys and research by the various JCOLD technical sub committees, papers presented JCOLD participates in 24 technical committees at Annual to the ICOLD Congress, and results of activities by the Meeting and exchanges technical information. Japan Association of Dam & Weir Equipment Engineering are reported widely to people concerned with dams. In JCOLD held Annual Meeting in 1960(Tokyo) and addition, the lecturers and participants in the Technology 1984(Tokyo), and Congress in 2012(Kyoto). Lecture and Discussion Meeting discuss the reports in order to improve the technologies, maintenance, and operation of Susumu NAGATA(1957-1960), Masayoshi NOSE (1966- dams. 1969), Shigeru ICHIURA (1982-1985), Kyohei BABA (2001-2004), Norihisa MATSUMOTO(2007-2010) and Tadahiko SAKAMOTO(2011-2014) served as a vice president of ICOLD.

3 DAMS IN JAPAN - OVERVIEW 2018

Table-1 Number of participants from Japan Table-2 Number of submitt ed Congress papers Number of Number of Host country Host country Year participants Year No. submitted (Host city) (Host city) from Japan papers 1998 India (New Delhi) 43 1933 1 Sweden (Stockholm) 3 1999 Turkey (Antalya) 56 1936 2 United States (Washington) 5 2000 China (Beijing) 87 1955 5 France (Paris) 4 2001 Germany (Dresden) 60 1958 6 United States (New York) 13 2002 Brazil (Iguazu) 47 1961 7 Italy (Rome) 8 2003 Canada (Montreal) 49 1964 8 United Kingdom (Edinburg) 13 2004 South Korea (Seoul) 143 1967 9 Turkey (Istanbul) 11 2005 Iran (Tehran) 77 1970 10 Canada (Montreal) 8 2006 Spain (Barcelona) 107 1973 11 Spain (Madrid) 12 2007 Russia (St. Petersburg) 79 1976 12 Mexico (Mexico) 9 2008 Bulgaria (Sofia) 63 1979 13 India (New Delhi) 11 2009 Brazil (Brasilia) 46 1982 14 Brazil (Rio de Janeiro) 12 2010 Vietnam (Hanoi) 75 1985 15 Switzerland (Lausanne) 17 2011 Switzerland (Lucerne) 70 1988 16 United States (San Francisco) 22 2012 Japan (Kyoto) 398 1991 17 Austria (Vienna) 29 2013 USA (Seattle) 73 1994 18 South Africa (Durban) 25 2014 Indonesia (Bali) 79 1997 19 Italy (Florence) 28 2015 Norway (Stavanger) 80 2000 20 China (Beijing) 16 South Africa 2003 21 Canada (Montreal) 20 2016 58 (Johannesburg) 2006 22 Spain (Barcelona) 23 2017 Czech Republic (Prague) 84 2009 23 Brazil (Brasilia) 15 2012 24 Japan (Kyoto) 37 2015 25 Norway (Stavanger) 16

Dams in Japan

Development of dams in recent years, redevelopment projects, such as raising the height of dams, excavating reservoirs, and upgrading In Japan, the major purpose of dams was irrigation from discharge facilities, are being carried out more and more. ancient times to the end of the feudal period in the mid nineteenth century. The Sayama-ike irrigation pond (Osaka Prefecture), which is considered to be Japan’s oldest dam, was completed in 616, and is recorded in the official historic documents.

As Japan was modernized and urbanized after the Meiji Revolution (1867), Japan started to build dams with modern technology, to meet the increased demand for water and electric power. In 1900, the Nunobikigohonmatsu Dam (Hyogo Prefecture) was completed as water supply dam. As for hydropower, the Chitose No.1 Dam (Hokkaido) was first completed in 1910. Later, multi-purpose dams with flood control capacity were constructed, with the first, the Kodo Dam (Yamaguchi Prefecture), completed in 1940.

To make more efficient use of water resources and control of flood, comprehensive projects are promoted under the concept of integrated development of river systems. Also, Figure-5 Nunobikigohonmatsu Dam

DAMS IN JAPAN - OVERVIEW | 2018 DAMS IN JAPAN - OVERVIEW 2018 4

Figure-6 Development of Dams, Economy of Japan and Population Figure-6 Development of Dams, Economy of Japan and Population

Major dams in Japan Major dams in Japan

There areare many many dams dams over over 100 100meters meters high inhigh Japan, in though,Japan, though,their reservoir their reservoir capacities capacities are smaller are than smaller those thanof other those dams of otheraround dams the aroundworld, reflectingthe world, th reflectinge geographical the geographical features of featuresJapan (narrow of Japan islands (narrow and islands steep terrain). and steep terrain).

Table-3 Ranking of dams by height in Japan Dam name Type Height (m) 1 Kurobe Dam Arch 186 2 Takase Dam Rockfill 176 3 Tokuyama Dam Rockfill 161 4 Naramata Dam Rockfill 158 5 Okutadami Dam Gravity 157 6 Miyagase Dam Gravity 156 6 Urayama Dam Gravity 156 Figure-7Figure-7 ＮNaramataaramata DamDam 6 Nukui Dam Arch 156 9 Sakuma Dam Gravity 155.5 10 Nagawado Dam Arch 155

Table-4 Ranking of dams by reservoir capacity in Japan Reservoir capacity Dam name (million m3) 1 Tokuyama Dam 660 2 Okutadami Dam 601 3 Tagokura Dam 494 4 Yubari Shuparo Dam 427 5 Miboro Dam 370 6 Kuzuryu Dam 353 7 Sakuma Dam 343 8 Ikehara Dam 338 Figure-8 Miyagase Dam 9 Sameura Dam 316 10 Hitotsuse Dam 261 Figure-8 Miyagase Dam

5 5 DAMS IN JAPAN - OVERVIEW 2018 DAMS IN JAPAN - OVERVIEW | 2018

Hydroelectric power plants in Japan Taable-6ble-6 ElectElectricric powepowerr output rrankinganking of PumpePumpedd Storage hydhydropowerropower pplantslants The output of hydroelectric power plants in Japan accounts The output of hydroelectric power plants in Japan accounts Electric for about 19% of all electric power sources, and pumped DDamam nnameame for about 19% of all electric power sources, and pumped Hydroelectric ppowerower storage hydroelectric power occupies top 10s of the electric ((upperupper resreservoirervoir / storage hydroelectric power occupies top 10s of the electric ppowerower pplantlant ooutpututput power output rankings. lowerlower rreservoir)eservoir) power output rankings. ((MW)MW) KKurogawaurogawa DamDam / 1 OOkutataragikutataragi 1 1,932,932 Tataragi DaDamm Table-5 Electric power output ranking of Conventional KKassaassa DDamam / Table-5 Electric power output ranking of Conventional 2 OOkukiyotsukukiyotsu 1,6001,600 hydhydropowerropower pplantslants FFutaiutai DaDamm KaKaoreore DaDamm / 3 OOkuminokumino 1 1,500,500 Electric KaKamiosumiosu DaDamm HHydroelectricydroelectric ppowerower ppowerower Takase DaDamm / DDamam nnameame 4 ShShintakasegawaintakasegawa 1 1,280,280 pplantlant ooutpututput NanNanakuraakura DaDamm (MW) (MW) Ota Dam / 4 Okokouchiuchi 11,280,280 1 Okutada Okutadamimi 560 Okutada Okutadamimi Dam Hase DaDamm 2 Tag Tagokuraokura 4 40000 Tag Tagokuraokura DDamam Seto DaDamm / 6 OOkuyoshinokuyoshino 1 1,206,206 3 Sak Sakuummaa 3 35050 Sak Sakumauma DDaam AsAsahiahi DDamam 4 K Kurobegawaurobegawa 4 335335 KurobeKurobe DamDam TamaharaTambara DDamam // 7 TaTamaharambara 1,2001,200 5 Ari Ariminemine 1 265265 ArimineArimine Dam FFujiwaraujiwara DDamam 6 Ted Tedorigawaorigawa 1 250250 TedorigawaTedorigawa DamDam DoDoyoyo DaDamm / 7 MMatanogawaatanogawa 1 1,200,200 7 Miiboroboro 2 21515 M Miboroiboro DaDamm MMatanogawaatanogawa DamDam 8 S Shinojiyahinojiya 2 20606 M Miyanakaiyanaka DamDam OusOuseuchieuchi DDamam / 7 OOmarugawamarugawa 1 1,200,200 9 Hit Hitotsuseotsuse 1 18080 Hit Hitotsuseotsuse DaDamm IIshikawauchishikawauchi DDamam 1100 Sh Shinanogawainanogawa 177177 NishiotakiNishiotaki DamDam KaKamihikawamihikawa DDam/am/ 7 KKazunogawaazunogawa 1 1,200,200 KazKazunogawaunogawa DamDam

Figure-9 Okutadami Dam Figure-10 Kurobe Dam DAMS IN JAPAN - OVERVIEW 2018 6

Dams completed in 2014 - 2016 in Japan

Dams completed in 2014-2016 in Japan are counted in 15 dams. The features are summarized below. Several dams are illustrated in the following pages.

Dam

Length of Reservoir Dam name Location Height Owner Completed Purpose(s) Type Crest capacity （ｍ）（ｍ）（million ㎥） 1 Toppu Hokkaido CSI PG 78.4 309 36 Hokkaido Pref. 2014 2 Yofudo Hyogo CS PG 54.4 145 1.1 Hyogo Pref. 2014 3 Rogi Kumamoto CS PG 53 169 2.3 Kumamoto Pref. 2014

The Tohoku Regional 4 Isawa Iwate CSIH ER 127 723 143 2014 Development Bureau, MLIT*1

5 Naganuma Miyagi CS TE 15.3 1050 31.8 Miyagi Pref. 2014 6 Kyogoku Hokkaido H ER 54 332.5 5.5 Hokkaido Electric Power Co.,Inc. 2014 7 Kin Okinawa CSI CSG 39 461.5 8.6 Okinawa General Bureau 2014

Hokkaido Development Bureau, 8 Yubari Shuparo Hokkaido CSIH PG 110.6 390 427 2015 MLIT*1

9 Kirimegawa Wakayama CS PG 44.5 127 4 Wakayama Pref. 2015 10 Kurikara Hyogo CS PG 26.7 172 0.4 Hyogo Pref. 2015

Kyushu Regional Agricultural 11 Tokunoshima Kagoshima I ER 56.3 266.9 8.1 2015 Administration Office, MAFF*2

12 Hamada 2 Shimane CS PG 97.8 218 15.5 Shimane Pref. 2016 13 Shobara Hiroshima CS PG 42 118.5 0.7 Hiroshima Pref. 2016

The Tohoku Regional 14 Tsugaru Aomori CSIH PG 97.2 342 140.9 2016 Development Bureau, MLIT*1

15 Gima Okinawa CS TE 24.5 539 0.6 Okinawa Pref. 2016

Purpose: C - flood control, S - water supply, I - Irrigation, H - hydroelectricity Type: PG - gravity in masonry or concrete, ER - rock fill, TE - earth, CSG - CSG

*1 Ministry of Land, Infrastructure, Transport and Tourism

*2 Ministry of Agriculture, Forestry and Fisheries 7 DAMS IN JAPAN - OVERVIEW 2018

Isawa Dam

＠ The Tohoku Regional Development Bureau, MLIT

Lo w U e p r D pe ive r D rs ive io rs n ttu io un n t ne unne l l

Figure-1 Plan DAMS IN JAPAN - OVERVIEW 2018 8

Axis of dam

Cresat elevation EL. 364.000 S.W.L EL. 356.500 DFWL EL. 361.000 H.W.L in Flood Season N.H.W.L EL. 345.600 EL. 342.900 Surface Protection Surface Protection

L.W.L EL. 304.500 Internal Internal External Rockfill Core Rockfill Section Rockfill External Section Clay Section Rockfill Filter Filter Section Zone Zone Auxiliary Dam

Blanket Grouting

Main Curtain Grouting

Figure-2 Typical section

Left Bank Entrance (Access road to Administration Building) Crest length Right Bank Entrance

Cresat elevation EL. 364.000 DFWL EL. 361.000 S.W.L EL. 356.500 N.H.W.L EL. 345.600 H.W.L in Flood Season EL. 342.9

Upper Diversion Tunnel Access Road to Lower Elevator Lower Diversion Tunnel

Figure-3 Longitudinal Cross Section 9 DAMS IN JAPAN - OVERVIEW 2018

Kyogoku Dam（ Pumped-storage Hydroelectric Power Station ）

＠ Hokkaido Electric Power. Co., Inc.

Cresat elevation

Crest length of dam

Figure-1 Plan of upper reservoir DAMS IN JAPAN - OVERVIEW 2018 10

Figure-2 Section of upper reservoir

Crest length of dam

Axis of dam Cresat elevation

Figure-3 Plan of lower Dam（Kyogoku）

Axis of dam

Cresat elevation

Figure-4 Typical section of lower reservoir（Kyogoku）

Figure-5 Longitudinal Cross Section 11 DAMS IN JAPAN - OVERVIEW 2018

Kin Dam

＠ Okinawa General Bureau

Cresat elevation DFWL NWL SWL

Figure-1 Plan DAMS IN JAPAN - OVERVIEW 2018 12

0 10 20 30 40m ( 1: 500)

EL(m)X+240 X+220 X+200 X+180 X+160 X+150 X+140 X+120 X+100 X+80 X+60 X+40 X+20 X- 0 X- 40 X- 80 X- 120 X- 160 X- 180 X- 200 X- 220 X- 240 80 Spillways 30000 Crest length 461500 15000 13500 27@15000=405000 13000 15000 Non Overflow section 187000 Overflow section 81500 Non Overflow section 193000 60 Emergency spillways 36500 15000 2000 2000 2200 2200 2000 Emergency spillways 13000 13000 12900 12800 12900 6500

BL29 BL28 BL27 BL26 BL25 BL24 BL23 BL22 BL21 BL20 BL19 BL18 BL17 BL16 BL15 BL14 BL13 BL12 BL11 BL10 BL9 BL8 BL7 BL6 BL5 BL4 BL3 BL2 BL1

J 29 J 28 J 27 J 26 J 25 J 24 J 23 J 22 J 21 J 20 J 19 J 18 J 17 J 16 J 15 J 14 J 13 J 12 J 11 J 10 J 9 J 8 J 7 J 6 J 5 J 4 J 3 J 2 J 1 J 0 40 Water intake facility

EL29. 000 28. 0 27. 0

25. 5 24. 0

22. 5 8 8

21. 0 . . 0 0 : : 18. 75 1 20 18. 0 1 Spillways EL17. 000 EL15. 000 EL15. 000 EL13. 000 Ｂ3. 20× Ｈ2. 15

. EL14. 000

EL9. 000 0

: EL12. 000 1 EL11. 000 EL4. 500 EL3. 500 EL9. 000 EL0. 000 EL0. 000 0 導水管 EL- 2. 000 EL1. 000 EL2. 000 EL- 2. 000 φ 1100

- 20

- 40

- 60

- 80 Figure-2 Upstream elevation

Axis of dam

1900 8000 6000 EL（m）

30 EL29. 000 DFWL 27.200 SWL 25.600 25. 600

0 . 1 : 1

NWL 21.500 EL21. 000 0 0

20 5 1 8 1 . : 0 0 : 0 . 1 0 8 0 6 R

ＣＳＧ 1000

1000

10 EL 9. 000

LWL 6.000

1500 E L 2. 700 1 0 : 1 0 EL0. 750 . 0 0 2 EL 0. 000 0 0 0

5 EL - 2. 000 2

1 0 : 1 0 . 5 5 1 0 0 0 2

- 10

Figure-3 Typical Section 13 DAMS IN JAPAN - OVERVIEW 2018

Yubari-Shuparo Dam

＠ Hokkaido Development Bureau, MLIT

8 EL21

LEVEL

EL218 EL218

8.1% 進入路

S=1:1000

夕張ダ大看板ム放

Power station 流

ーブル柱ケ光

60°

ラフ300 ト 10%

擁壁

配線ル光ケーブ EL218

土留壁

護岸ブロック擁壁

230 EL226

Auxiliary dam 街灯

電柱 NTT

10%

10.0％

EL224 EL221 225

電柱 Valve chamber

. 500

ＥＬ225 Energy dissipation

Grouting tunnel 1:2.0 1:2.0 1:2.0 1:2.0 1:2.0 1:2.0 EL213.500

EL225.0 0

EL265.0 EL260.0 EL255.0 EL250.0 EL275.0 EL270.0

6 5 EL217.5 EL213.500

EL215.0 EL220.000

L EL218.000

2 EL217.000 EL217.000

EL225.0 EL228.000

E .

EL226.000 L

EL232.000 0

EL235.000 E .

L EL223.000

0 EL238.000 2

0 EL224.000 E

EL232.000

2 0

EL241.000 3

L 0

. EL227.000

2 EL244.000

0 EL229.000

E 0

EL235.0 EL238.000

0 2

0 EL231.000 3

7.0 E 0

EL248.000 8 L

EL23 .

4 EL242.000 EL235.000 0 EL234.000

EL238.0 1

580 0

EL239.0

EL251.000 0

0 EL237.000 EL240.0

EL241.0 EL243.000

EL247.000 585 EL241.000 EL240.000

EL252.000

EL244.0 EL243.0 EL246.000

EL245.000

EL246.0 EL245.0 EL255.000 EL252.000 EL249.000

EL247.0

EL250.000 EL256.000

EL249.0 EL252.000 EL251.000

EL251.0 EL263.000 EL.285.

EL255.000

EL254.000 EL260.000 EL255.0

EL262.000 EL267.000

EL258.0 0 EL259.000 EL266.0 0

600 EL263.000 EL265.000 EL262.0 EL267.000 EL265.0 EL267.0 EL267.0 EL268.0

EL269.0 Water intake facility EL270.0 EL272.0 EL272.0 EL273.0 EL275.0 EL275.0

EL277.0 Grouting tunnel EL278.0 1:0.82 EL281.0 EL281.0 EL285.0 EL285.0 EL291.0 EL287.0 EL289.0 EL295.0 EL297.0

EL299.0 EL295.0 EL306.6 EL305.0 EL301.0 EL301.0 EL306.6 EL305.0

J26 Ｊ0 J1 J2 J3 J4 J5 J6 J7 J8 J9 J10 J11 J12 J13 J14 J15 J16 J17 J18 J19 J20 J21+320 J22 J23 J24 J25 J26 J0 Axis of dam EL277.0 EL247.0 EL246.0 EL245.0 EL244.0 EL243.0 EL242.0 EL241.0 EL306.6 EL240.0 EL236.0 EL234.0 EL238.0 EL270.0 EL268.0 EL267.0 EL265.0 EL261.0 EL256.0 EL255.0 EL254.0 EL253.0 EL251.0 EL250.0 EL249.0 EL248.0 EL276.0 EL274.0 EL272.0 EL257.0 EL289.0 EL278.0 EL291.0 EL287.0 EL283.0 EL279.0 EL225.0 EL228.0 EL230.25 EL232.0 EL234.0 EL237.0 EL239.0 EL241.0 EL243.0 EL245.0 El247.0 EL249.0 EL251.0 EL255.0 EL261.0 EL265.0 EL268.0 EL272.0 EL275.0 EL278.0 EL281.0 EL282.0 EL284.0 EL285.0 EL289.0 EL293.0 EL297.0 EL301.0 EL305.0 EL305.0 EL303.0 EL297.0 EL295.0 EL293.0 EL306.6 EL301.0 EL299.0

1:0.8 244 EL222.0 1：0.8

EL219.0 0

0 . EL299.0 EL242.0 EL241.0 EL240.0 EL239.0 EL238.0 EL234.0 EL303.0 EL301.0 EL297.0 EL236.0 EL232.0 EL235.0 EL237.0 EL239.0 EL241.0 EL243.0 EL245.0 EL247.0 EL249.0 EL252.0 EL279.0 EL281.0 EL282.0 EL283.0 EL251.0 EL276.0 EL273.0 EL272.0 EL250.0 EL275.0 EL270.0 EL255.0 EL.255.00EL253.0 EL252.0 EL248.0 取水塔 EL207.5 EL206.0 5

U形側溝工 9

0 1:1.0 EL209.0

1:1.2 EL230.25

. L

256 1：0.8

5 E

250 8

1:1.2 2

1:1.2 . 258 .

300 Axis of dam EL215.0

00 5 L

E 260 2

. EL.297.00

L EL220.5 EL216.0 EL210.5 EL.240. EL225.0 210

1:1.2 238

262 236 E

1:1.2 4 234 EL.215.00

26 EL.255.00 232

1:1.2 EL212.0

1:1.0

280 EL.265.00 1:1.2 266

EL.275.00

EL.283.00 EL207.5

268 270 210

1:1.2 作業構台 EL206

.00 ガ－ドロ－プ仮排水路ﾄﾝﾈﾙ EL.216.00

EL.287.00 230 25 2

EL.255.00 EL. EL.225.000 EL.216.000 220 右岸崖錘斜面対策工

5.00

23 EL. 1：1.2

EL.240.00 EL.245.00 1:0.5

EL.250.00 220 EL 218.000 EL 210.500 EL 213.500 EL 212.000 EL264.00 1:1.2 260 1:1.5

EL.230.00

2 .

：1 1

ⅰ＝10.0％ M

Emergency spillways M Emergency spillways 124000 41500 15000 12500 21200 57600 56000 53200 ⅰ＝10.0％ 12500×3+2000×24500 2500 Spillways12900×4+2000×3 2000 12500×4+2000×3 20000 ⅰ＝12.0％ 24@15000=360000 10000

Crest length 390000

Ｅ

Ｌ

0 M

EL266.50 M

Control office EL297.00

埋設ｵｲﾙﾀﾝｸ

犬走り

車庫棟

EL=308.575

2 . :1 1

EL=308.500 1：1.5

1：1.5

5.0%

EL=308.575

EL=308.500

15％

EL=301.500 1 :1.

EL=297.075

EL=297.000

1:1.2 EL=291.225

EL=291.150

EL=277.000 EL=284.150

EL=284.075 Figure-1 Plan DAMS IN JAPAN - OVERVIEW 2018 14

Overflow section S=1:1000 Spillways

Axis of dam Oyubari Dam 155000 EL（m） 320 2500 8000

Cresat elevation EL306.600 DFWL EL304.400 SWL EL301.500 300 NWL EL297.000 EL297.000

280

EL266.500 1500

F.W.L 264.500 76600

260 LWL EL259.600 1:0.82 EL256.000 Dam body Energy dissipation ダム高 H=110600

L.W.L 240.000 240 EL237.000

1:0.77 L.W.L 230.000 EL230.000 EL226.000 1:2.0

220 EL220.000 EL216.750 R=20000 Auxiliary dam EL215.500 EL214.000 1:0.80 EL213.500 1:1.0 34000

1:0.10 EL208.000 EL206.000 Apron EL206.000 EL205.700

1:0.5 EL199.000 200 Foundation rook EL196.000 1:0.5 2000

27200 90036 5464 78963 13300 16000 5000 6750 88000 39800 117236 118727

180 Figure-2 Typical section

Crest length 390000 EL（ｍ） 10000 53200 24@15000=360000 20000 Emergency spillways 56000 2000 Spillways 57600 21200 Emergency spillways 15000 4500 Emergency spillways 41500 124000 12500×4＋2000×3 12900×4＋2000×3 12500 2500 12500×3＋2000×2 320 Water intake facility

26BL 25BL 24BL 23BL 22BL 21BL 20BL 19BL 18BL 17BL 16BL 15BL 14BL 13BL J12 12BL J11 11BL 10BL 9BL 8BL 7BL 6BL 5BL 4BL 3BL 2BL 1BL Cresat elevation J26 J25 J24 J23 J22 J21 J20 J19 J18 J17 J16 J15 J14 J13 J10 J9 J8 J7 J6 J5 J4 J3 J2 J1 J0 EL306.600 EL304.600 HWL 304.400 1BL EL301.500 EL301.500 EL301.500 SWL 301.500 300 EL299.850 EL297.000 NWL 297.000 EL295.000

EL289.000

EL280.000 280 EL275.000 EL273.000

EL266.500 1:0.2 EL266.000

1：0.82 EL263.000

1:0.15 LWL 259.600 260 EL258.000 EL258.000

EL250.000 EL246.000 EL245.000 EL243.000 EL240.000 240 EL241.000 EL242.000 EL235.000 EL235.500 EL231.000 EL228.000 EL227.000 EL227.000 EL226.000 EL225.000 EL221.500 220

EL206.000 EL205.500 EL204.000 200 EL200.000 EL200.000 EL200.000 EL196.000

S=1：600

0 5 10 20 30 40 50 180

Figure-3 Downstream elevation 15 DAMS IN JAPAN - OVERVIEW 2018

Tokunoshima Dam

＠ Kyushu Regional Agricultural Administration office, MAFF

＠ Kyushu Regional Agricultural Administration office, MAFF DAMS IN JAPAN - OVERVIEW 2018 16

Intake tower

Control office

Outlet works

Power station

Spillways

Figure-1 Plan

EL.120.0m EL.120.0m 10,000

4,000 3,000 1,000 1,000 3,000 EL.110.0m EL.110.0m 13.3m Cresat elevation EL.106.30m ▽ HWL 103.50m▽ SWL 102.80m EL.100.0m ▽ NWL F.W.L.100.30m EL.100.30m EL.100.0m

EL.94.00m 2.00 EL. 90.0m 1 EL. 90.0m 2.60 1 0.20 0.20 EL83.0m 1 1 1 1 1 1 EL. 80.0m ▽ LWL D.W.L.79.60m Rock2 1.30 EL. 80.0m 1 1.20 0.20 0.20 2.60 Filter Rock2 Rock1 Core Rock1 Rock2 EL. 70.0m Filter EL. 70.0m

EL.67.50m Foundation rook EL. 60.0m EL. 60.0m

EL. 50.0m EL.50.00m Leakage EL. 50.0m Blanket grouting Blanket grouting EL. 40.0m EL. 40.0m

Curtain grouting

2,000 26,320 2,000 Curtain grouting

Figure-2 Typical section 17 DAMS IN JAPAN - OVERVIEW 2018

Tsugaru Dam

136.21

0 0 0

. 0 8 1

0 - . o

142.36 N 164.99 17 L L L L L L L L L 0

7 . o ） N 7 8 5 0 8 1 1 7 1 2 4 9 4 4 6 6 0 7 1. 1 134.62 空 7 3. 3 1. 3 1. 2 7. 1 9. 1 3. 8 9. 8 3. 7 7. 7 1. 6 9. 5 4. 5 3. 8 5. 8 1. 4 8. 8 9.

T-217 1 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 T-38 1 （ 146.54 1 67. 7 138.44 166.68

1 80. 2

0 ) 5 0 0 0 0 5 0

0 . 8 5 4 6 1

5 (

5 0

1 .

C B 7 0 0 3 4 0 .

1 6 8 4 1 8 = 6 R

5 3

0 5

0 5 138.28

0 0 0

5 5 0 9 9.

L 3

5 6

) 1 7 1 4 7 . + 7 . o N

2 (

1 7 9.

1 10

6 4

3 6 9

7 4 1 1

1 168 .1

2 1

. 0 o -2 N

- -

- - -

- -

L- 134.97 L

L L

R R 138.43 R R R R R

R R

R 1

137.87 137.49

1 . 139.89

18 152.67 1 140.73 . T-23 C

1 61. 2 136.50

E （岩）

0 T-224 6 163.58

= 145.17 5 ＠ The Tohoku RegionalR Development Bureau, MLIT 135.31 T-24 166.98 6 5. 1 5 4 8 4 4 7 0 5 6 1 5 7 3 137.66 3

1 82. 3 138.31 Ｗ 6 . 3 . 5 . 7 . 2 . 3 . 7 . 1 . 9 . 5 . 2 . 2 . 3 . 4 . 8 22 22 21 20 19 18 17 16 15 18 15 19 19 138.40 19 9 7. 152.48 137.14 1 140.84

1 1 1

142.20 P

8 .

147.25 137.88 S 6 .

8 1. . 15 o 1 N

146.50 17 1 65. 6 136.74 1 1 . 4 142.85 P 1 96. 2 152.49 0 138.18 I 152.13 144.67 152.49

0 T-216 T-226 6 T-40 149.72 6 8 5. 5 9. 4 . 1 1

19 T-22 137.25

146.25 138.73 153.21 150.73 168.00 220 .2 216 .2 206 .7 187 .4 198 .8 193 .4 184 .4 181 .4 171 .8 199 .3 162 .7 180 .1 200 .6 155 .7 195 .3 200 .4 6

5 6. 2

1 . o 151.73 N 0 9 7 ｗ 7 . 1 4 T-21 EL 151.02 T-225 140.48

6 Ｇ 7 .

18 143.77 150.60 T-20 159.70 1 : T-209 1 0 . 4 168.56 0 1 150.97 L 5 E 6 1 59. 4 V 0 E . 138.69 L 6 9

1 91. 0 136.77 o N 2 14. 3 2 04. 0 2 03. 7 1 94. 1 1 84. 5 1 70. 5 1 69. 3 2 01. 6 1 76. 9 2 05. 6

1 1 88. 4 156.78 : 2 06. 4 1 143.85 . 0 149.90 2 5 5 1

180 T-215 191 .8 189 .0 (休） 138.68 Ｇ 164.84 T-19 145.32 156.77

0 6

1 185.26

. 139.95 3

145.19

T-16 4

. 0

L E o

184 .4 143.15 137.24 N

. 3 149.25 1: 6 4 0 3 6 0 0 6 5 2 5 0 2. 9 12 70 90 0 9. 0 2. 9 8. 9 8. 9 9. 0 4. 7 9. 7 0. 6 1. 0 2. 1 1. 8 9. 138.92 1 1 1 2. 2 2 1 1 1 2 1 1 1 2 2 1 2 153.25 156.90 170.58 159.68 T-58 148.98 T-208 2 194.06

4 . ) 0

19 0 0

18 .

0 5

151.59 146.09 2 1

. (

8 T-246 1 83. 7

4 T-17 Ｇ 1

149.11 164.16

159.78 136.50 . 139.19 139.42 o

260 測線 148.39 N 144.98 260 測線 T-18 137.36 137.23 T-214 150 137.06

149.81 2

P 2 169.13

I .

T-15 145.21 P 153.23 0 S

143.48 0 139.34 川原平幹線76 0 ジャカゴ

5 6 7 5 8 0 7 4 3 0 0

8 1 169.56 1 8 . 5 . 2 . 0 . 8 . 4 . 7 . 0 . 2 .

1 （岩） 9 . 19 21 21 21 18 18 17 20 21

+EL150.000 21 0

= 202.92 160 R

158.18

0 2 0

. 0

0 167.04 C 2

1 3. 218.63 0 B

209 .7 167.42

2 211.44

0 6

. T-245

0 o 2 . N T-213 175.65 1 :1 143.58 1 T-180 198.04 158.50 T-54 J1 224.72 0 ％ 0 0 0 0 0 0 T-144 170 0 . T-247 T-212 0 . 207.26 0 1 1 171.19 178.94 = 6 218.22 0 i =

2 L 165.50

184.02 1

147.32 1

T-207 J =

T-14 9 R

174.86 199 .9 211 .2 192 .1 186 .1

157.07 142.82 139.00 139.40 216 .4 179.52 2

135.99 . C 218.02 209.13 230 測線 T-179 138.74 E 210 213.54 137.40 136.63 230 測線

144.18

211.46

0 7 （岩） 215.49

. o 0 J N 0 8 +EL135.000 Ｇ 139.45 180.49 0 5 T-143 143.67 T-206 1 234.76 22 220 217.80 182.79 1 218.15 8 136.93 231.53 0 160.78 208.82 218.59 139.62 146.73 T-248 137.55 223.82 T-53 176.71 Ｇ 0 .0 0 1 191.15 0 1: .0 T-299

5 137.39 1:1 T-211 222.43

1 180.68 5 3 3

) 227.84

. T-244 .

T-205 0

2 34. 2 2 07. 6 2 12. 1

. O O

5 8 N 1 N

T-142 1

T-13 0 (

5 . 0

137.56 8 0 .

3 :

5 T-298 T-181 11 148.28

238.43

137.53 J 224.47

180.47 6 136.34 . o 1

N :0. 230

T-178 7 180.99 T-140 0 7

246.33 141.08 = 138.01 R

1:0. 4

0 5 3 0 . T-52

177.11 0 O

250.70 185.62 1 160.81 136.40 5 137.08 135.81 1 181.47 N 0 J 139.76 3 :

0 : 1 144.16 0 167.27 186.84 T-249 209.19 227.81 234.29 230.63

200 測線 0 0. 5 . . 227.99

P 3 . . 5 8 P 0 136.88 S 200 測線 7 I 211.05 L1 1 E 0 147.66 : 00 T-141 1 . Ｇ 1 0 9 . :0 6 2 1 1 0 1 .8 : EL 138.35 : 0 ° 0 214.24 253.53 . 147.51 . 1 8 T-210 0 5 235.62 L 0

: E 8 0 1 V .

E 8

. ′ 182.18

1 L 2

= 170.45 T-250

° T-243 0 141.30 0 T-51 0 4 J 178.62 0 4 ″

137.70 235.13

0 0 N o . 9 175.13

197.18 137.65 4

1 1 = 0 7 257.22 2 R 4 1:1.2 4 . 244.32 2 45. 7 T-6 22 205.00 243.51

T-12 屋外 182.59 0 0 ) . 1 ( 1 5

142.31 4 239.73

161.67 24

1 5 3 . 8 0

207.93 1:1.2 0 173.68 0 240.41 変電設備 T-297 137.51 （岩） 249.93 138.51 0 5 T-9 1 T-10 1:0.8 0 1:1.0 J3 16 260.67 .1 T-177 248.53 1 0 : 175.08 1 Ｇ T-184 138.14 EL240.0 3 . 203.57 189.32 1 175.78 25 T-7 T-11 149.74 130.80 137.14 Power station : 136.17 140.37 158.73 183.32 170 測線 1 176.39 206.47 253.18 248.65 244.32 244.14 T-8 213.11 . 177.37 T-242 EL242.5

25 0 屋内 260.60 170 測線

0 243.78 207.57 （岩）

0 o . 1 2 N 1 00 川原平幹線78 0 : 00 1

226.93 0. 変電設備 5

17 137.89 . L 266.25 .

E 7 138.50 ％ T-296 0

254.86 1 0 0

1 0

9 EL237

. 2 : 10 0 J2 . 175.65 4

3 1 1 1 251.51 5

= : = T-241 2

i L

1 201.61 . 1 . 144.70 （岩） 259.90 8 11 0 0 0 90 0 155.04 7 264.36 139.75 EL23

° 5 160 測線 50 1: 2

0 0 +EL135.000 1:1.0 . 2 00 0 1:1.0 1:1.0 216.19

6 . 5 0 T-138 0 213.64 60 ′ 207.53

1 T-176 1 EL :

1 0 270.63 225.25 195.62 1 268.97 : 138.76 ″ 251.32 261.12 0 . 267.13 221.77 8 T-251 +EL150.000 177.93 146.52 T-240 244.43 1:0.8 216.37 1:0.8 1:0.8

266 .6 1:1.0 1:0.8 137.44 T-182 253.60 o . 1 1 2 N

20 222.34

T-5 1:0.8 176.59 176.95 1:1.0 150 測線 0 ) 0 0 . ( 5 1 1:0.8 0

1 J1 185.91

: 174.51 0 0 0 5 0 3 . 1 1 1 0 253.05 .0 :1.0 2 1:0.5 Valve chamber 219.72 142.55 0 0 16 161.20 215.21 0 0 0 00 178.48 1 2 0 2 260 3 . 0

0 0 1 L 0

1 5

2 : 152.80 271.93 0 224.00 . 265.88 L 0 Ｇ VE

1 254.77 241.72 229.62 T-134 E . 202.48 160.21 0

T-185 1 8 133.10 133.20 149.23 167.06 LE 179.02 = 195.48 217.66 245.63 268.02 257.50 259.94 263.09 140 測線 L

0 T-1350 1:0.5 178.15 140 測線 0 0 0 5 0 . 0 0 137.51 141.26 1 240.26

0 .0 1 1:

. 0 1.0 2 2 0 . 0 + : 1

0 20 0 T-293

232.41 1 2 J0 0 o . 1 1 :1 L . N . 138.89 2 0 2 E 8 T-190 260.40 L 142.25 2 24 230.85 E 203.40 172.19 0 1:1. 0 1:0.5 179.60 272.37 T-295 0 00 256.96 . 1 1:1 1 T-133 216.97 90 : 153.58 1 .0 :0.8 1:0 L1 0 :1.0 .8 252.26 240.13 1:0.8 E . 175.47 173.25

8 0 0 174.31 177.10 5 3

1 2 T-239 T-131 0 139.96 245.62 1:0.8 00 1:0.75 . 1 0 268.62 80 : (Co) 7 L1 0 T-175 1 E . 268.40

8 0 261.53 231.88 T-137 15 T-292 227.45 1: 0 273.66 0. 1 269.69 8 0 .

E E 245.82 0 E

L T-183 L L 0 180.55 T-230 1 6 T-277

2 259.34 .0 15 2 2

1:0.5 4 5 243.77 208.00 0 E L 17 1 7 7 7 EL : 140.32 223.64 0 265.68 .8 1:1.0 1:1.0 T-132 T-136 162.03 00 . 0

G 8 0 0 0

1 00

: L 1

0 0 196.67 . 143.86 E . 0 8 . 00

T-139 181.51 0 . 0 174.91 1 0 1 9

4 L 2 192.57 T-186 L 2 1:0.8 1:0.8 E L E E T-291

255.35 7 249.53 234.43 208.90 182.06 171.02 T-174 137.45 WC 219.14 1:0.8 1:0.8 1:0.8 137.70 154.85 173.27 186.18 . 181.72 197.38 110 測線 145.34 245.39 270.38 266.48 270.09 283.86 193.15 0

200.59 00 00 110 測線

: 12

1:0.8 . 0

1 138.64 138.78

174.57 2 0

1 1:0.5 Control L 2

L E T-130 E T-234 00

. 0 （岩） T-278

0 T-238 2 6

L 2 166.45 Conduit gate T-96 タ

265.08 0 E T-189 Spillways 266.27 148.83 246.67 8 office 137.06 254.42 1 00 1:0.8 （空） T-276

212.84 4 . 0 T-171

5 265.41 1 0 193.45 T-283

7 T-191 2 268.16 274.35 234.16 5 E L2 183.05 174.80 0 270.04 183.58 （岩） 137.52 2 4 265.61 8 0 260.31 Spillways . 286.56 0 1: 1: 1: 0.8 4 0.8 170.52 5 7 . 1:0.724

0 . 0 0 :

0 0 1

1:0 4 . .8 : 床固床固 0 床固 7 273.21

2 1

259.94 2 . 0 8 93 L 7 6 1 T-169 0 . E 0 Grouting 1 T-279 1:

: 259.34 260.30 237.58 214.15 190.36 182.67 167.29 216.58 .8 T-237 139.15 1 T-282 0 139.48 158.65 172.88 184.30 200.56 1: 241.83 T-129 80 測線 264.31 272.75 80 測線 278.36 288.03 T-235 E L2 1 169.74 4 90 1:0.634T-275 7 tunnel 184.40 142.47 Inspection gallery T-170 268.93 2

2 2 .

2 8

8 2 T-236

8 2

2 2 1

1 8 82

1 1 8

. 1 :

. 1

1 .

1 18

0 0. .

0 .

. . 1

: :

: 0

0 :

0 0 +EL227.000

1 :

1 :0 :

: 1

1 262.25 1

1 Ｇ 1 Axis of dam 189.36 266.40 T-168 140.13 265.51 257.25772.72 236.34 213.47 201.22 199.88 191.62 184.58 176.39 162.99 139.32 2 140.23 160.68 171.19 Intake tower185.57 200.82 00 242.11 264.02 268.59 279.66 5.07 65 測線 +EL.221.80 E 290.33 T-271 L 217.25 65 測線 2 190.02 37

0 0 0 Cresat elevation EL226.700 17

0 0 170.18

265.16 . T-280 264.73

7 7 . 169.43 190.13 3 T-188 2 0 . 60 測線 2 1:1.0 1 6

L 23 : 1

0 1

0 1:1.0 T-1 E （岩） 60 測線 T-270 1:1.0 0 T-172

0 0

267.74 268.68 .

7 T-274 264.77 7 . 4 0 C 測線 1:1.0 0 7

2 C 測線 2 4 0 1 EL170.000

L 140.45 3NO.1 0 1:1.0 5

E E L . 0. T-192

7 7 .0 00 210 : 5 1 1:0.899

2 2 5 1:1.0 263.97 L 1:1.0 1:0.697 Inspection gallery

E E L T-269 266.07 234.05 214.97 5 5 213.09 0. . 190.67 140.19 139.58 : 163.96 141.62 166.49 172.26 1:1.0 186.84 201.27 211.54 244.10 50 測線 1 0 259.71 265.55 278.31 287.12 256.30 5 : +EL160.000 . 1 1 T-281 50 測線 T-167 0 1 1:0. :1. 1:0.738 5 : : 8 1 0 00 0. 1 0 :0. . 8 . 0 1: 2 179.34 5 . 2 0 1 :

1 1 5 EL160.000 L 2 : EL160.000 0 5 . 187.24 EL180.000 0 E

220 0 0. 0 5 0 1:0. EL140.000 . .

1: : 1:1.0 192.39 5 0 259.09 T-112 1 9 261.52 222.25 1 T-272 5 L 1 T-154 0 172.11 E . 5 0 177.61 : 5 1 6 T-94 0 . . T-152 1 T-187 0 1 : 1 0 : 212.91 1 0 1 5 . .0 0 5

1: 0 1 187.68 1

0 : 0 . 床固 : . 1 1 0 0 236.62 : 199.16 141.92 0 0 1 275.17

1 . 0 260.46 1:1.0 . 2 5 0 L 141.96 191.60 0 E 1 2 210.97 :1 265.72 285.10 T-173 L . T-155 5 169.06 1: E 0 （岩） E 144.93 1 EL1E70L170.000 .0 229.78 L 0. .0 .000 1 1 : : 6 146.45 0 1 1 5 255.42 T-149 . 0 4 235.94 0 1 252.67 230.20 0 230 T-153 .5 149.40 1: T-273 T-113 0 209.69 0 1 174.65

. Meya dam . .0 1 E : 0 : L 1 147.98 1 1 17 5

. 0 155.93 1: .0

0 :0 0 0

（岩） 1 5 8 192.09 . 1 0 0 : 155.93 158.46 0 EL 1 0 242.56 1 . 224.20 8 206.30 166.71 156.67 157.09 0 258.46 0. T-157 165.30 177.11 EL1E8L1800..000000 187.95 188.24 9 1: 200.88 209.73 20 測線 T-151 00 1 1. 247.48 257.19 271.97 283.10 5 L 0 235.40 210.24 0 E 251.84 247.07 233.56 5 . 231.68 20 測線 . 0 3級 BM.1 0 164.39

: 0 E 1 1: 175.98 L1 1:1.0 . 187.539 90 185.50 5 . T-156 :1

0 1 T-150 0. 00 1: 5 252.06 253.54 . 1:1.0 245.54 :0 5 248.75 EL 1 . 171.89 254.70 2 0 235.46 210.0103 : 256.62

. 1 0 0 192.59 4 00 178.13 176.45 0 2 230.08 0 174.90 5 . 2 1 : 177.93 244.59 E 1 L2 179.43 178.47 (As) 10 5 248.55 T-114 . . 0 00 0 1. 0 0 : . : 185.49 1 1 243.59 1 248.80 : EL 1 182.45 235.00 2 224.28 201.52 187.93 20 187.90 187.91 187.92 227.41 241.54 0 測線 .0 187.90 195.26 204.70 257.94 270.50 284.06 229.36 00 187.87 T-126

209.72 T-79 T-93 0 測線

247.29 .0 188.57

0 0 1 T-92

244.98 . : 188.24 o

236.53 o 1 T-158

N N T-91

239.77 T-128

）

） 174.21

ﾄ

3 211.56

ﾝ 185.43 173.15

ｲ

ﾟ 4

ﾎ

ｷ 1

+ ｰ

0 190.74

ﾚ 225.11 川原平35 ﾞ 181.78

175.45 189.99 204.79 245.75

ﾌ

№ 264.45 272.48 283.41 （

（ 7

. 225.74

236.49 233.29 o 223.23 N 2

211.98 2 237.00 188.86 T-127 L

19 T-159 E 230.76 237.21 T-125 186.02 266.60 T-95

（岩） 274.81 30 233.70 285.56

233.27 2 231.76 T-160

2 258.07 .

. N 189.33

o T-124

230.74 N 5 .

230.73 3

4 .

N . 176.06 o

o 222.90 2 7 7 N 262.43

. 223.17 N T-161 0

o 1 N 8 0

223.30 2

223.10 223.37 0 8

. 223.00

o BL 1 BL 2 BL 3 BL 4 BL 5 BL 6 BL 7 BL 8 BL 9 BL10 BL11 BL12 BL13 BL14 BL15 BL16 BL17 BL18 BL19 BL20 BL21 N BL22 BL23 T-162 (As) 181.07 220 （岩）

202.23 224.69 250.20 262.01 273.05 284.55

218.14 190.55 J 0 J 1 J 2 J 3 J 4 J 5 J 6 J 7 J 8 J 9 J10 J11 J12 J13 J14 J15 J16 J17 J18 J19 J20 J21 J22 J23 T-304 217.18 208.82 T-123 212.86 213.50 美山湖 T-163 川原平幹線86 174.45

0 0

5 5 2

5 0 0

5 0

5 0 6 0

8 5 6 1 4

0 5 0

0 5 (Co)

0 5 0 1

3 5

6 9 186.35 190.01 1

1 1

2 2

1 1

7 6 5

3 211.52 4

3 4

9 1 1

1 1 1

1 1

1 213.89 Figure-1 Plan 1 2

- -

- - - -

- -

-9

- - - -

-1 - 岩木川第一発電所73 T-305 -

L L L L L

L L L

R-

R R R R R

R R

R- 青森県 2 0 5 21 207.87 237.72 0 211.03 207.45 275.14 DAMS IN JAPAN - OVERVIEW 2018 18

EL.(m) Axis of Meya dam Axis of dam 240

60000 9000 Cresat elevation EL 226.700 DFWL EL 224.500

220 SWL EL 216.300

NWL EL 204.900

200

Cresat elevation

EL 187.500 1 : 0 . 7 DFWL EL 186.000 4 NWL EL 183.000 180 Dam body Energy dissipation HWL in flood season Left bank 152974（Right bank 92780） EL 170.500 LWL EL 170.000 97473 3000 23000

00 50 =1 R 0 160 00 LWL EL 160.000 15 R= 12058 3700 1 : 0 . EL 152.500(Right bank) EL 153.500(Left bank) 1 7 :2 5 .0 EL 151.000 0 0 1500 6 50 0 EL 148.000 =1 3000 . R

: EL 146.00 1 0 30000 00 15 R= 1000 EL 142.000 0 5000 4000 17500 17500 0 6 0 16000 140 10 . 1 R= 0 : : 1. 1 0 7000

EL 135.00 5000 EL 135.000 1000 Foundation rook EL129.500 2000 Diversion conduit B5.0×H4.5m 120 87.0m 44000 45473

11100 71928 3490 89473 10000 24000

62.8m 123473

Figure-2 Typical section

R - 180 R - 165 R - 150 R - 135 R - 120 R-110 R-105 R-100 R-95 R-90 R - 75 R - 60 R - 45 R - 30 R - 15 CL L - 15 L - 30 L-45 L-50 L-55 L-60 L-65 L-70 L-75 L - 90 L - 105 L - 120 L - 135 L - 150 L-165 L - 180 EL(m) EL(m)

320 320

300 300

280 Crest length 342000 280

16000 10@15000=150000 2@18000=36000 9@15000=135000 5000 Non Overflow section 126900 Overflow section 96200 Non Overflow section 118900 2000 13000 2000 13000 2000 13000 2000 13000 2000 13000 2000 13400 2000 12700 2000 12700 8500 6100 12200 6100 8500 12700 2000 12700 2000 13400 2000 13000 2000 13000 2000 13000 2000 13000 2000

1418 1418 1418 1418 260 5665 5665 260

J23 J22 J21 J20 J19 J18 J17 J16 J15 J14 J13 J12 J11 J10 J 9 J 8 J 7 J 6 J 5 J 4 J 3 J 2 J 1 J 0

BL23 BL22 BL21 BL20 BL19 BL18 BL17 BL16 BL15 BL14 BL13 BL12 BL11 BL10 BL 9 BL 8 BL 7 BL 6 BL 5 BL 4 BL 3 BL 2 BL 1

240 240 取水設備

Cresat elevation EL226.700

EL221.000 EL220.000 220 220 : 0.18 2 1: 0 .18 2 1 1 :0.1 82

EL205.000 12000 EL201.756 EL201.756 3000 200 200 EL198.000

4 EL1944.000

EL193.000 0.74 1 : :0. 7 Spillways 1 Spillways EL188.750 EL187.000 B4.3×H4.4m 12000 B4.3×H4.4m 4000

180 4 180 EL177.000 EL176.000

EL175.000 :0. 7 3000 6000 1 Conduit gate 6000 呑口：φ6.019m EL170.000 EL167.000 吐口：B3.9m×H3.6m 6375 3000

12000 10000 5625 2000 3000 3000 EL159.577 EL160.000 160 EL158.577 160 EL157.000

EL154.000 EL153.500 EL154.000 EL152.500 12000 EL150.000 EL150.000 3000 EL145.250 EL144.000 12000 EL143.000 3000 140 140 3000 5000 EL142.000 EL135.000 5000 2000 EL133.000 EL130.000 EL129.500

12000 DiversionDiversion conduit conduit 12000 120 3000 B5.0×H4.5m 3000 12000 7400 3100 15000 15000 2250 3000 4500 3000 750

100

9100 15000 15000 18000 18000 15000 6100

Figure-3 Downstream elevation 19 DAMS IN JAPAN - OVERVIEW 2018

IntroductionIntroductionIntroduction to to toDam Dam Dam Technologies TechnologiesTechnologies in inJapan JapanJapan

TrapezoidalTrapezoidalTrapezoidal CSG CSG CSG dam dam dam the damperformancethe bodydam bodymaterials ofmaterials the require material require less strength,isless low strength, andthe requiredthere the required are few performancerestrictionsperformance of onthe of the materialthe selection material is lowof ismaterials,” andlow thereand “Rationalizationthereare feware few The trapezoidal CSG dam developed in Japan is a new restrictionsofrestrictions design: on theThe on selection trapezoidalthe selection of materials,” shape of materials,” improves “Rationalization “Rationalization seismic stability, The trapezoidalThe trapezoidal CSG damCSG developed dam developed in Japan in Japanis a new is a type new type type of dam which combines the characteristics of a of design:andof design: so The the trapezoidal Thestrength trapezoidal requiredshape shapeimproves of improvesthe seismicdam bodyseismic stability, materials stability, is of damof whichdam which combines combines the ch thearacteristics characteristics of a trapezoidalof a trapezoidal trapezoidal Dam and the CSG (Cemented Sand and Gravel) and solower,”and the so strength andthe strength“Rationalization required required of the of ofdam theconstruction: bodydam bodymaterials Constructionmaterials is is Dam Damand andthe CSGthe CSG(Cemented (Cemented Sand Sandand andGravel) Gravel) construction method. It rationalizes the construction of lower,”worklower,” and can “Rationalization and be “Rationalizationexecuted rapidlyof construction: of byconstruction: simplified Construction Construction construction constructionconstruction method. method. It rationalizes It rationalizes the constructionthe construction of of dams in three ways: “Rationalization of materials: because workfacilities.” workcan becan executed be executed rapidly rapidly by simplified by simplified construction construction dams damsin three in threeways: ways: “Rationalization “Rationalization of materials: of materials: because because the dam body materials require less strength, the required facilities.”facilities.”

ProtectionProtecti concreteon concrete

Protection concrete CSG CSG Protection concrete

Structural Structuralconcrete concrete InspectionIns gapellerycti on gallery

Seepage cSoneepagetrol con concretetrol concrete Rich mix CSGRich mix CSG

Auxiliary curtain Auxiliary gr oucurtainting grouting

FoundationFounda drain hotionle drain hole

Curtain grCurtainouting grouting

Figure-1Figure-11Figure-11 Concept Concept Conceptof Trapezoidalof Trapezoidal of Trapezoidal CSG CSG dam CSGdam dam Figu reFFigure-2-i1g2ure To-1b2 eTobetsut TsuobD eatsum DamD am Sediment bypass tunnel (SBT) concrete dam in Japan, Nunobikigohonmatsu Dam (1900), Tachigahata Dam (1905), Asahi Dam (1998), Miwa Dam SBTs are one sustainable and effective strategy against (2005). Also, they are currently undergoing trial operation sedimentation. The SBT connects upstream and at Koshibu Dam and Matsukawa Dam. The problem downstream of a dam and bypasses sediment-laden floods of SBTs is countermeasure against invert abrasion and into downstream. They are mainly operated in Japan, elucidation of sediment hydrological behavior, and research Switzerland and Taiwan. is currently under way. In Japan, SBTs are operated at the oldest

Figure-3 Sediment bypass tunnel (SBT) Figure-4 Miwa Dam

Preservation measures of dam reservoirs One of water quality preservation measures for the dam reservoir is conducted by controlling outflow of pollutant Water quality issues are closely associated with the size of and nutrient salts from the catchment area. the dam reservoir, and operation of the dam reservoir. DAMS IN JAPAN - OVERVIEW 2018 20

Aerating circulation Fence Aerating circulation FenceFence Aerating circulationTo change water temperature distribution or other To prevent the spread of algae or to shift the conditions inadequate for algae growth nutrient flow away from surface to middle layer To cTohan change waterge water tem temperatureperature distri distribubutiontion or or ot otheher r ToTo prev prevenent tthe the spr spreadead of ofalg algaeae or orto shiftto shift the t he condconditionitison inades inadequaqteua forte for alg algaeae growth growth nunutritrienent flowt flow away away from from surface surface to mito ddmiledd layerle layer No operation Operation No No ope operationration OOpeperationration

Upper stream UppUpperer stream stream Lower stream LoLowerwer (Dam stream stream side) (Dam (Dam side) side)

Figure-19 Reservoir Water quality facilities Figure-19Figure-5 Reserv Reservoiroir Water Water quality quality facilities facilities Figure-19 Reservoir Water quality facilities Inflow of Sunlight Inflownutrien ofts Sunlight Inflownu oftri en ts Sunlight nutrients Algae blooms Algae blooms Selective Algae blooms Algae blooms SelectiveDischarge Algae blooms Algae blooms DiscSehalectiverge Shading DiscToha rgeselect adequate water depth to Shading To select adequate water depth to intake better quality of water Shading intakeTo select better ade quaqliuaty ofte waterwater depth to Fence Fence intake better quality of water AuAuxiliiliary Dam Fence Auxiliary Dam ToTo reduce the lloadoad ofof AirAi formr form Air Aiformr form nunutritrients to a dadamm reservoirreservoir To reduce the load of withwith particulate nunutritrienentsts Air form Air form nutriensesetsttttl ledto a dam reservoir with particulate nutrients settled AeratingAerating circulation circulation ByBypapassss Aerating circulation ByTopaTo cutss cut o ffo ffthe the nu nutrientrients tsinflow inflow Figure-20 Example of quality conservation measures To cut off the nutrienFigure-20ts inflow Example of quality conservation measures Figure-20 Example of quality conservation measures Figure-6 Example of quality conservation measures to time. AdvancementAdvancement ofof floodflood control control operation operation to time. Advancement of flood control operation toTherefore, time.Therefore, the theappropriate appropriate operation operation is conducted is conducted at all at all Advancement of flood control operation times,Therefore, making the useappropriate of the rainfall operation prediction is conducted technologies at all Recently,Recently, flood disastersdisasters causedcaused byby heavyheavy rains rains occur occur Therefore,times,times, making making the useappropriate useof theof therainfall operation rainfall prediction predictionis conducted technologies technologies at all Recently,frequently floodin Japan. disasters It is set causedthat the floodby heavy control rains operation occur andand flood flood outflow outflow analysis analysis model andmodel maximizing and maximizing the flood the Recently,frequently flood in Japan.disasters It is causedset that theby floodheavy control rains operationoccur times,and makingflood outflow use of analysis the rainfall model prediction and maximizing technologies the flood frequentlyof the dam in should Japan. workIt is setmost that effectively the flood for control design operation flood controlflood capacitycontrol capacityof the dam of theso damthat sothe thatprevention the prevention or frequentlyof the damin Japan. should It iswork set thatmost the effectively flood control for designoperation flood andcontrol flood outflow capacity analysis of the model dam andso maximizingthat the prevention the flood or ofscale the and dam design should wave work form. most However, effectively as the rainfall for design is a mitigationor mitigation of flood of flooddamages damages can becan achieved be achieved in the in the of thescale dam and should design work wave most form. effectively However, foras designthe rainfall flood is a controlmitigation capacity of offlood the damagesdam so thatcan thebe preventionachieved inor the floodnatural or phenomenonhydrograph. the However, rainfall conditionas the rainfall varies isfrom a natural time downstreamdownstream areas. areas. scalephenomenonnatural and designphenomenon the wave rainfall form.the conditionrainfall However, condition varies as fromthe varies rainfall time from to is time. timea mitigationdownstream of floodareas. damages can be achieved in the natural phenomenon the rainfall condition variesAvoidan fromce of inund timeation downstream areas. Nabari River Avoidance of inundation Actual water level Nabari River WaterActual level without water leveldams Avoidance of inundation About 1.5 m WaterWater Level oflevel without dams Nabari River Actualnormal waterdam operation level Water Level of of Adraboutwdo 1.5wn m Water level without dams 8.0 normal dam operation Nabari City of drawdown DesiAboutgn high 1.5 Water m level Water Level of Urban area Nabari City 8.0 normal dam operation of Nabari ofDesi dragnw hidoghwn Water level Urban area Hinachi Dam 8.0 City Nabari City of Nabari Hinachi Dam Design high Water level

Urban arCieaty Water (m) Level of Nabari HinaShochiren Damji Dam

City 6.0 Water (m) Level Shorenji Dam

Water (m) Level 6.0 Shorenji Dam 6.0 Murou Dam Water level at Nabari City, downstream of 3 dams Murou Dam ･ Water level at Nabari City, downstream of 3 dams MurHeavyou Dam rain due to big typhoon threatened to cause inundation in Nabari River on October 8, 2009. Water level at Nabari City, downstream of 3 dams ･Heavy rain due to big typhoon threatened to cause inundation in Nabari River on ･Japan Water Agency’s O&M offices conducted collaborative operations in view of water ･ October 8, 2009. Heavylevel, rain rainfall, due toand big dam typhoon capacity threatened of each of theto threecause dams inundation under its inintegrated Nabari control.River on ･ October･JapanThe above 8,Water 2009. figures Agency’s show O&M that theoffices water conducted level of urbancollaborative area was operations kept below in theview design of water ･Japanlevel,flood Water waterrainfall, Agency’s level and at O&MdamNabari capacity offices City. conductedof each of thecollaborative three dams operations under its integratedin view of control.water level,･The rainfall, above figuresand dam show capacity that ofthe each water of theleve threel of urbandams underarea was its integrated kept below control. the design flood water level at Nabari City. ･The above figuresFigure-21 show Floodthat the control water levethroughl of urban integrated area was and kept collaborative below the design operation of three dams flood water level at Nabari City. Figure-21 Flood control through integrated and collaborative operation of three dams Figure-21Figure-7 Flood Flood control control through through integrated integrated and and collaborative collaborative operation operation of ofthree three dams dams 21 DAMS IN JAPAN - OVERVIEW 2018

Dam Upgrading Vision promoted by effectively using existing dams applying both hard and soft measures according to each basin’s It is important to effectively use existing stocks while characteristics and issues. Typical examples are shown in controlling total costs. Various technologies will be figures. These exhibit that dam upgrading to effectively advanced as the number of cases of the effective use of use existing dams has features and effects such as greatly existing dams grows. On the other hand, more frequent increasing water storage capacity with the slight raising of and intense flood damage and more frequent droughts dam bodies, or the economic completion of work in a short are concerns. Under this context, dam upgrading will be period of time, to show effects more quickly.

Figure-8 Projects and Technologies to effectively use dams DAMS IN JAPAN - OVERVIEW 2018 22

The “Dam Upgrading Vision” which provides a strategy 6) Addition of Hydropower for the further promotion of dam upgrading efforts that 7) Protection and Revitalization of River Environment effectively utilize existing dams has been formulated in 8) Regional Development utilizing the Dams 2017. These strategies for the vision are categorized below. 9) Promoting Dam Upgrading Technologies Overseas 1) Dam Life Extension 10) Development and Implementation of Technologies to 2) Promoting Efficiency and Advancement of Maintenance Promote Dam Upgrading 3) Flexible and Reliable Operation to Optimally Utilize the Capacity of the Facility 4) Improving Facilities for a more Advanced Functionality 5) Responding to Climate Change

Utilization of ICT in construction of dam Utilization of ICT in construction of dam In addition, using ICT to share information in real time and The construction industry in Japan aims at drastically Into addition, utilize andusing accumulate ICT to share 3-dimensionalinformation in real data time can contribute The constructionimproving industry productivity in Japanof all aimsconstruction at drastically production andto ato dramaticutilize and rationalization accumulate 3-dimensional of actions data throughout can the dam improving processesproductivity by utilizing of all ICT, construction and its approach production is called i- contributelife cycle to froma dramatic the designrationalization stage, ofthe actions construction stage to processes byConstruction. utilizing ICT, and its approach is called throughoutthe operation the dam and life maintenance cycle from the stage. design stage, the i-Construction.Even in the construction of dams, the utilization of ICT has construction stage to the operation and maintenance Even in thebeen construction advanced toward of dams, improvin theg utilizationquality, safe siteof ICTwork, stage. has been advancedshortening towardof construction improving period, quality, and reduction safe site of work, shorteningconstruction of construction cost. period, and reduction of construction cost.

Figure-9Figu rApplicatione-● Applicatio nof o fICT ICT fforor D Damam C oConstructionnstruction 23 DAMS IN JAPAN - OVERVIEW 20182015

Papers in ICOLD & Other Technical Publications

Theme 1 Safety supervision and rehabilitation of existing dams

A. ICOLD 84th Annual Meeting International Symposium in Johannesburg, May 2016

Development of emergent monitoring system for leakage External deformation monitoring of five rockfill dams in from the dam the same radar satellites data

T. Higuchi, T. Sugai, T. Sato, and T. Kayukawa H. Sato, T. Sasaki1, T. Kobori, Y. Enomura, Y. Yamaguchi, W. Sato, N. Mushiake, K. Honda and N. Shimizu In this paper, the development of 24-hour monitoring system for leakage from the dam by using goods on the market will be intro- It is important to research new methods of conducting effective duced. From the middle of November in 2013, the IWAYA Dam measurements of the external deformation of embankment dams. Management Office had conducted 24-hour alert condition because External deformations of five rockfill dams in the same SAR data of unexpected increasing leakage from the dam body and its shal- were measured in about four years, and the results of external low foundation. The initial monitoring system for leakage volume deformations using SAR data were compared with those by GPS had some drawbacks in terms of conducting 24-hour alert condi- or conventional survey data. We found that the results of external tion. Some engineers of the IWAYA Dam assembled ad-hoc mon- deformations using SAR data agreed well with those by GPS or itoring and alert system developed by using goods on the market, conventional survey data and the average error of the external such as a smartphone. deformations between SAR and GPS or conventional survey was about five millimeters. Suggestions for dam crisis management learned through The 2011 off the Pacific Coast of Tohoku Earthquake Inspection of submerged area with the use of an underwater camera survey vehicle H. Okumura, T. Matsumoto, and K. Koyama Y. Sakamoto, S. Akimoto and K. Kera On 11th of March, 2011, the 2011 off the Pacific coast of Tohoku Earthquake, with a moment magnitude of 9.0, hit on Numappara Japan Water Agency (JWA) has the standard for the dams as river dam. Immediately, more than 1,000 l/min of leakage increasing management facilities managed by the JWA. All the daily patrol, which was assumed to run through caused cracks on the asphaltic inspection, maintenance and repair work, etc. are being imple- facing was detected. To avoid a possible serious failure, the water mented based on this standard. But for the areas not exposed, there level was drawn down to the safe one. This paper describes the has been no measure of conducting the visual inspection. JWA suggestions for dam crisis management learned through these therefore came up with an idea of using an underwater-camera to responses taken for the Earthquake and also focuses on the impor- inspect the usually submerged part of the facilities and conducted tance of the usual dam monitoring. the test at concrete arch dam and rockfill dam. As a result, it was proved that with both dams there were no damage or degradation.

B. 4th Asia Pacific Group Symposium and th9 East Asia Dam Conference, September 2016

Dynamic characteristics of dams evaluated using dam height, dam-reservoir interaction and mechanical properties of the transverse joints. In addition, the applicability of microtrem- earthquake monitoring data for safety assessment or measurement is verified for another method of identifying the predominant frequency of dams through the in-situ measurement M. Kashiwayanagi, H. Onishi, N. Osada and S. Hayakawa of an arch dam. It is concluded that the dynamic characteristics of the dam examined can be utilized as management indices to reveal Earthquake monitoring is normally conducted in high dams in an abnormal situation or degradation of the dam by detecting their Japan. Detailed analysis of dam behaviour during an earthquake deviations. helps to identify the mechanical properties of the dam which could reflect its current soundness. This paper focuses on the effective utilization of earthquake monitoring data for the safety manage- Study on the deformation mechanism of an ageing dam ment of dams. Data on concrete gravity dams, arch dams and aiming at future deformation prediction rockfill dams are examined so as to elaborate the management criteria in terms of the response characteristics and the predominant H. Onishi, M. Kashiwayanagi and M. Yoda frequency. Such dynamic characteristics of concrete dams are formulated with influential factors, which are finally identified as the In evaluation of dam behaviour, deformation monitoring is es- DAMS IN JAPAN - OVERVIEW 20182015 24 sential. Although most dams show a stable deformation trend, it Investigation and repair on deteriorated transverse joint of is highly important to confirm whether these trends will continue in the future assuming that the lifespan of a dam is more than 100 Kasabori dam years. If unique deformation behaviours have been encountered in a dam, such as monotonic increase toward the stream direction of H. Kawasaki and S. Iwasaki the dam and variation in the deformation degree corresponding to reservoir water level or the ambient temperature, the current defor- Kasabori dam is a concrete gravity dam with height of 74.5m mation mechanism, future dam behaviour, and also the necessity of completed in 1964 by Niigata prefectural government in a snowy correspondence should be addressed considering dam safety in the region, for the purposes of flood control and hydropower. It was future. In this report, we studied the deformation and related data redeveloped in 1973-79 and again in 2011-17 to upgrade its flood of a 50-year-old concrete gravity dam and interpreted the deforma- control function. The present work, which started in 2014, includes tion mechanism with the aid of numerical analysis, and conducted heightening the dam by 4m, placing concrete on its downstream a simulation of dam behaviour in an elastic and steady manner surface to increase its thickness by 2m, renewing its two gates, and considering the three parameters of reservoir water level, ambient extending its spillway. However, a visual inspection confirmed a temperature, and sediment depth. The results of the simulation serious increase of water leakage around the J2 transverse joint, show the consistent dam behaviour against these loads acting on and the extension of cracks along J2 since the first repair in 1973- the concrete gravity dam usually. 79. Thus, before the main work, repair work started in 2014 and, cutting down around J2 by line drilling was performed after low- Application of global positioning system for dam ering the reservoir level. After water-stop installation and steel-bar reinforcement, the concrete was placed, and the J2 repair work was deformation monitoring finished by June 2015. Experientially, there were some difficulties coping with the transverse joint trouble (Kawasaki, H., et al. 2014). H. Arizono, H. Okumura, H. Onishi and N. Shimizu In this paper, we introduce the investigation process and the repair work on the traverse joint, and try to explain the mechanism of de- Renovation of safety monitoring system of existing dams has terioration by earthquakes and heavy freezing-thawing. been becoming one of main issues for dam owners. In this regard, Global Positioning System (GPS) has been applied for dam external deformation monitoring in considerable numbers of existing Improvement of deformation prediction of Rock-fill dam dams in Japan. Electric Power Development Co., Ltd. which is one with GPS measurement of the electricity utility companies in Japan, and owns rather old dams for hydropower stations, has started to utilize GPS for dam H. Soda, S. Nigo and N. Sato deformation monitoring for some years, and it has been applied in five dams. Since GPS enables to obtain the data more frequently Accurate and continuous data accumulation of deformation mea- than those obtained by the conventional manual measurement, surement of dam body is important for proper dam safety man- it is useful to figure out deformation characteristics and its long- agement. Regarding the improvement of the accuracy of rock-fill term trends more precisely. In addition, since digital data can be dam deformation survey, there are problems that the measurement obtained automatically and transmitted online, it is also useful to frequency is low and the accuracy may be affected by slight dif- acquire the status in real time, even if personnel cannot access to ferences in measurement techniques and by observer. In recent dams. On the other hand, the accuracy of GPS data is prone to be years, Global Positioning System (GPS) measurement system affected by some external factors such as climate conditions, sur- which enables us to measure the exterior deformation of rock-fill rounding plants growth. This paper shows continuous monitoring dam bodies continuously, accurately and three-dimensionally have data of dam deformation by GPS through case histories in five been developed and is experimentally introduced in about 20 dams dams and their effectiveness as well as countermeasures actually in Japan. The authors, based on the approximate expressions cor- provided to improve foresaid matters. responding to the long-term settlement of the embankment, have proposed approximate expressions of settlement and the horizontal displacement by using the GPS measurement data in Tokuyama Dam. As a result, predicted deformation by using the approximate expressions well matched to the value measured by GPS measurement system. Based on the research results in Tokuyama dam, it is possible to monitor other dams by proposing approximate expressions using the same method that utilizes the features of the GPS of high precision and continuous observation data.

C. ICOLD 85th Annual Meeting International Symposium in Prague, July 2017

Technical solutions on concrete for Kasabori dam trol function by heightening the dam by 4 m. On the other hand, this project term was limited to seven years due to disaster resto- heightening ration grant project, and the workable days of a year are largely restricted because of avoiding heavy snow season and flood season. H. Kawasaki, S. Iwasaki, T. Miyano and Y. Hagiwara So, the major challenge is how to complete the construction in a short period. The project includes various works such as concrete Kasabori dam is a gravity-type concrete dam with height of 74.5m placing on the downstream face and crest, renewal of two crest constructed in 1964 by Niigata Prefecture for the purpose of flood gates, improvement of the spillway and energy dissipater, repair control, power generation, etc.. After a serious flood damage in of the transverse joint, and grouting to the dam foundation. In this 2011, the redevelopment project started to upgrade the flood con- paper, we focus on the rational designing of dam heightening and 25 DAMS IN JAPAN - OVERVIEW 20182015 the seismic safety evaluation, the crack control measures and unifi- Deformation monitoring of rockfill dams in normal times cation of new and old concrete, and the speed up and facilitation of complicated work site by precast forms. and after earthquakes using satellite SAR data H. Sato, T. Sasaki, M. Kondo, T. Kobori, A. Onodera, Inspection of construction joints in the concrete dam body Y. Yamaguchi, K. Yoshikawa, D. Sango and Y. Morita by the impact elastic wave method For development of efficient and advanced deformation monitoring S. Ichikawa, T. Kamada, T. Sugiura and N. Hayashi methods for rockfill dams in normal times and after earthquakes, we studied monitoring methods using satellite SAR (Synthetic Ap- The deterioration of the horizontal construction joints, which may erture Radar) data. Because satellite SAR doesn’t need any sensors affect the stability of the dam body is one of the phenomena of the on dam surfaces and it can observe entire surface of rockfill dams aging concrete dams. The inspection by boring survey has been and obtain data regardless of weather conditions, it is expected to used to verify the state of the construction joints in the dam body. contribute in monitoring of deformation of rockfill dams. In this However, there are some problems in taking boring survey because paper, we evaluate external deformation of a rockfill dam using it is costly, it needs to destroy even a very small portion of the dam satellite SAR data in about four years. The dam has three targets on body, and it can just check the spots, not the area. Therefore, the the crest for survey and we compared the results of external defor- study was made on the non-destructive survey method to use the mations by satellite SAR and survey at the points. We found the re- reflective wave of the elastic wave input by the impact, this method sults of external deformations using satellite SAR data agreed well was applied for the survey of dam body of which the horizontal with those by survey and the average error of the external deforma- construction joints might be deteriorated. The following points tions between SAR and survey was about several millimeters. We were revealed: Estimation of the state of the construction joints also investigated tendency of external deformations of dam surface by this method coincided with that from the boring survey from a where survey had not been conducted. In addition, we conducted practical standpoint.; This method enabled us to grasp the deterio- studies of deformation monitoring after earthquakes using satellite rated construction joint area in the concrete dam body. Additional- SAR data to grasp damage on rockfill dams by 2016 Kumamoto ly, proper set-up of the strength of sound portion and deteriorated earthquake. We found satellite SAR data could detect small defor- portion of the construction joints enabled us to judge the safety of mation of rockfill dams by the earthquake. the dam body.

D. ICOLD 86th Annual Meeting International Symposium and 26th ICOLD World Congress in Vienna, July 2018

External deformation monitoring of nineteen rockfill dams mined on the basis of data accumulated over a period of several tens of years. Because of considerable temperature fluctuations, using satellite SAR data however, that are thought to be attributable to climate change in recent years, assumed temperature fluctuations have become in- H. Sato, M. Kondo, T. Koboir, R. Ishikawa, T. Sasaki, W. Sato, creasingly greater. Consequently, analytical results tend to deviate N. Mushiake, T. Sato and K. Honda from actual concrete conditions so that thermal cracking risk is growing not only in the block under consideration but also at other It is important to research new methods of conducting effective locations. To address this problem, therefore, a three-dimensional measurements of the external deformation of embankment dams. model covering the entire dam structure including the foundation In this paper, based on data collected by Synthetic Aperture Radar bedrock is constructed to conduct thermal stress analysis and deter- (SAR) satellite, a basic examination was carried out regarding the mine the thermal cracking index distribution over the entire dam. applicability of SAR to the external deformation measurement On the basis of the results thus obtained, multiple blocks having a of rockfill dams. Because no measurement facilities on the dam relatively high probability of occurrence of thermal cracking are surfaces are needed for SAR, SAR technique will lead to cost re- identified, and detailed two-dimensional thermal stress analysis is duction for external deformation measurements of embankment conducted. At the time of concrete placement, changes in concrete dams. This paper reports the results of satellite SAR based external temperature are monitored continuously by use of temperature deformation monitoring of nineteen rockfill dams in Japan in about sensors installed in the dam body, and the measurement results are two years from late 2014 to early 2016. The results of external checked against concrete temperature history simulation results deformations using satellite SAR data were compared with those based on past atmospheric temperature data. If the temperature by GPS or electro-optical survey data. We found that the results of difference is greater than predicted, appropriate control measures external deformations using satellite SAR data agreed well with such as regulation of temperature and cooling can be taken. In the those by existing geodetic data and the average error of the external newly developed system, the relationship between the temperature deformations between SAR and existing geodetic survey was about difference between the exterior and interior of dam concrete and five millimeters. the thermal cracking index is determined so that thermal cracking risk can be managed quantitatively by use of the thermal cracking index calculated from the temperature difference. The risk management of thermal cracking for concrete dams subjected to unprecedented temperature fluctuations Empirical evaluation of seepage of fill-dams using due to climate change reservoir level and rainfall E. Hasegawa, Y. Miyata and T. Kase H. Soda, J. Ishiguro, K. Otagaki and K. Kishida

Temperature data used in thermal stress analysis are usually deter- Seepage of fill dams is generally measured by observation equip- DAMS IN JAPAN - OVERVIEW 20182015 26 ment installed on the downstream side of the cutoff zone in the landslides around reservoirs” was published by the Japan Institute dam body and at the toe of the slope. Seepage is an important item of Construction Engineering. This manual was revised in July 2009 measured to evaluate the safety of a dam, but seepage of a dam as the guideline titled “Technical Guideline for investigations and is impacted by noise such as the rise or fall of the RWL or the countermeasures of a landslide around a reservoir” by the Ministry rainfall, so safety of a dam is evaluated only during a period when of Land, Infrastructure and Transportation. Uniform and systematic these impacts can be ignored and assuming that seepage has not investigations and stability analyses can be performed based on the increased from the past level at the same level. The authors have manual and the guideline. Not one disaster has ever been caused attempted to evaluate seepage behavior based on the range of past by a reservoir landslide in Japan, because suitable countermeasures RWLs and seepage quantity at a sampled dam that was constructed are taken based on the results of many kinds investigations of res- 30 years ago. This paper presents the range ervoir landslides. of seepage based on past RWLs and rainfall and proposes an evaluation method based on this range. Application of the transfer function matrix method in a dam engineering History and present state of investigations on landslides caused by reservoir filling: A review M. Kashiwayanagi and Z. Cao

Y. Wakizaka Transfer function is essential for the seismic design and safety evaluation, etc. of structures. In order to improve the evaluation The internationally most famous landslide caused by reservoir accuracy of the transfer function, the authors proposed the transfer landslide is the landslide at the Vajont Dam in Italy in 1963. Be- function matrix method considering mutual interference between fore the occurrence of the landslide at the Vajont Dam, reservoir vibration directions. In this study, the applicability of the proposed landslides occurred at many Japanese dams such as the Ishibuchi method in the field of dam engineering is investigated. It has been Dam, Shichikawa Dam, Naruko Dam, Kanogawa Dam and Futase concluded that the proposed method can give out more recogniz- Dam. Since the occurrence of the landslide at the Vajont Dam, able dynamic characteristics than the conventional method. It is reservoir landslides occurred at the Shimokubo Dam, Shingu applicable to the earthquake response prediction of dams at low Dam, Yanase Dam, Odo Dam, Hachisu Dam and Takizawa Dam. cost without relying on a numerical model. Furthermore, it shows In 1995, a manual titled “Investigations and countermeasures for the possibility for utilizing in the deterioration diagnosis of dams.

Theme 2 New construction technology

A. 4th Asia Pacific Group Symposium and th9 East Asia Dam Conference, September 2016

The underwater excavation by the shaft-style underwater Construction of a coastal levee at Hamamatsu city excavator T-iROBO UW coastline using trapezoidal CSG dam technology

N. Yachi, H. Miura,and A. Ueyama N. Itoh, T. Suzuki, S. Terada, T. Fujisawa, Y. Kinouchi and N. Yasuda In order to solve the problems caused by deterioration and the in- efficiency of the conventional method in redevelopment of existing In order to mitigate giant tsunami damage predicted to occur on the dams, a shaft-style underwater construction machine (T-iROBO Hamamatsu city coastline, a coastal levee higher than Level-1 tsu- UW) was developed and utilized in the Amagase Dam redevelop- nami is being constructed about17.5 km from Lake Hamana to the ment project in Uji city, Kyoto prefecture. The machine is operated mouth of the Tenryu river. Here, Level-1 tsunami is a tidal wave remotely to ascend, descend, rotate, to crash and gather the rock which occurs as the result of an earthquake of magnitude (M) 8 using a power shovel that is fixed to a shaft that goes down from with the return period of roughly 100-year to 150-year along Suru- the barge to the lake bottom, for underwater works. The underwater ga-trough and Nankai-trough. The planned coastal levee is located excavation is carried out while observing several monitors at the on a long sandy beach with a seaside protection forest parallel to it same time. One of the monitors shows landform of the lake bottom on the north side. Considering the conservation of valuable plants in 3D graphics, using the data obtained by investigation of sonar and animals, the seriously eroded shoreline, and the scenic appear- device. On the 3D graphics of landform, the movement of the ance of the site, basically the ground level of the seaside protection power shovel is featured in animation, by measuring the angles of forest is raised and CSG (Cemented Sand and Gravel) is placed at the arm of the power shovel. The ultrasonic camera is used to pro- the center of the levee section and the outer sections are construct- vide the operator a real-time image on the other monitor. It is also ed as earth dikes. The planned coastal levee is required to have possible to replace attachments of the power shovel, and currently tenacity enabling it to withstand overflow of Tsunami but, strength the underwater breaker, bucket, and pump are being used. This is a equal to that of a concrete structure is not needed, so a CSG struc- report of the development of T-iROBO UW and its performance. ture, which has been developed by dam engineering, is adopted for the internal portion of the levee. 27 DAMS IN JAPAN - OVERVIEW 20182015

Construction of Gokayama Dam by the cruising RCD water content of fine-grained and wet soils is an important issue for the improvement of core quality. In this background, we developed construction method a machine called “Mantis”, which can blend fine-grained soil and coarse-grained material efficiently even though the mix has a very R. Nishiyama, M. Yugeta, T. Toyomasu, H. Yotsumoto, T. Fujisawa, high content of fines and water. We used a crawler type soil mixing Y. Kinouchi and N. Yasuda machine, called “Stabilizer” which was improved with a fan for sending hot air produced with engine’s exhausted heat. Finally, we RCD (Roller Compacted Dam-Concrete) construction method was carried out a trial blending test at the stock yard. We found that the developed as a rationalizing dam concrete placing method and has processed material was well mixed and its water content was re- been used to speed up the construction works of concrete gravity duced. dams. The cruising RCD construction method adopted to construct Gokayama Dam has been developed to aim for even more rationalizing dam concrete placing, and which improves construction work Large-scale dam body drilling by Tsuruda Dam efficiency by advancing the placing procedure of the internal RCD, redevelopment project so it enables the continuous placement of dam concrete and enables placement of concrete more speedily. In Gokayama Dam, the K.Kaji, K. Oobayashi, K. Miyahara, T. Fujisawa, H. Yoshida and slumping concrete is placed in the outer concrete and RCD is place N. Yasuda in the inner concrete. Originally, the RCD is not placed unless the placement of slumping concrete is finished in one lift. The cruising RCD construction method is that the placement of RCD starts from The Ministry of Land, Infrastructure, Transport and Tourism is one side of the dam site, while the slumping concrete is placed at now redeveloping Tsuruda Dam. The objective of the project is to the other side of the dam site. In that case, the RCD is placed at improve its flood control function by increasing its flood control the next lift. Simultaneously, the RCD and slumping concrete are capacity and installing 3 additional large outlets for flood control. placed at different two lifts. The placement of RCD antecedent to Remarkable features of the project are its large scale: 6m diameter that of the slumping concrete enables this execution, unlike the holes and 4.8m diameter outlet. And the height of the dam crest conventional RCD construction method in which the slumping above the holes is more than 60m. This work had to be executed concrete is placed antecedent to that of RCD. while ensuring Tsuruda Dam’s flood control and water supply functions, requiring the construction of a cofferdam in the reservoir before drilling the dam body. Because underwater work at the large Construction of Apporo trapezoidal CSG dam depth was necessary, we developed a new type of floating cofferdam. This report introduces an outline of large-scale dam body S. Yoshimura, S. Takasugi, M. Konno, T. Fujisawa, H. Yoshida and drilling at Tsuruda Dam redevelopment project. N. Yasuda

The Apporo Dam is the second trapezoidal CSG dam in Hokkaido, Proposal of the rationalization of dam construction quality following the Tobetsu Dam. At the Apporo Dam, the shale is used control as the CSG material, which is the dam body material, and the dam is constructed on the foundation of the shale and shale-sandstone H. Yoshida and M. Kusumi alternative layer. Shale has the characteristic which causes the slaking phenomenon when it is dried, so various technical studies were The Dam Construction Technology Research Group of the Japan conducted to prepare for its use. For the concrete gravity dam, shale Society of Dam Engineers studied rationalization of the quality or mudstone cannot be used as the aggregates, so the aggregate for control of the dam construction work. We surveyed many cases of the Apporo Dam with original concrete gravity type was planned to quality control of dam construction executed in recent years and purchase from quarry place. Furthermore, the foundation surface of conducted a study based on execution data concerning the possi- the dam is extremely uneven and bumpy, so the investigation was bility of rationalizing quality control. Based on the results of this carried out to select the execution machinery. According to the ex- study, we proposed the rationalization of quality control of future tent and depth of undulation, the proper spreading and compaction dam construction work. machinery are used in the Apporo Dam. As existing Tobetsu Dam and Kim Dam with trapezoidal CSG type had an even foundation surface, large-size construction machine was chosen. So, this kind Development of embankment material grading control of investigation has an important role for the construction of the continuous management system using three-dimensional new Trapezoidal CSG dams. image processor

Development of a crawler type soil mixing machine with M. Fujiwara, W. Nakane, I. Miyairi, M. Omata, T. Otake, dryer function I. Kobayashi, T. Hashizume and A. Nakamura

S. Yamada, T. Temmyo, T. Koshida, I. Sandanbata, H. Itoh and In dam construction, grading control of embankment material is of vital importance in quality control. The conventional practice is A. Yamagishi to take samples and carry out sieve analyses at regular intervals, which is both labor- and time-consuming. When constructing a This paper describes a newly developed soil mixing machine with trapezoidal dam with cemented sand and gravel, it is standard prac- dryer function. Regarding the core embankment of rock-fill dams, tice to produce embankment material by mixing locally available fine-grained soil and coarse-grained gravel must be mixed uni- earth material such as riverbed deposits and excavated material formly and efficiently in the stockpile. When the fine-grained soil with cement and water. In order to achieve the required strength of is relatively wet, compared to optimum water content, blended soil embankment material, therefore, grading control checks need to be becomes difficult to be mixed uniformly because fine-grained soil made to ensure that its strength is kept within the allowable range. tends to become what is called “clay lumps”. Therefore reducing The authors have developed a new continuous grading manage- DAMS IN JAPAN - OVERVIEW 20182015 28

ment system using three-dimensional image processing technol- thereby determining particle size distribution. The usefulness of the ogy. The newly developed system makes real-time monitoring of system has been verified by using it for a countermeasure against grading possible by irradiating line laser light onto the material on landslide in which cemented sand and gravel embankment material the conveyor, calculating the volume of particles of each size from was used. This paper introduces the new system and reports the the image data continuously acquired with a digital camera and field verification results.

B. ICOLD 85th Annual Meeting International Symposium in Prague, July 2017

Dam concrete compaction management system Analyzing sizes from continuous image data obtained with a digital camera and determining particle size distribution in real time. By using concrete vibration to decide when to stop compacting particle size distribution measurements obtained from the newly developed system in combination with moisture content measure- K. Uekoua, H. Furuyab, W. Nakanec and S. Sakazume ments obtained with radioisotope moisture meters, the quantities of cement and water to be added to produce cemented fill materials Compaction of concrete is of vital importance in dam construction can be controlled in real time. This report deals with functions of a when trying to attain the required water-tightness, durability and fully automatic cementitious mix production system consisting of strength of the dam body. Viback concrete vibrator systems are these components. usually used to compact conventional slumpable mixes. Decision as to when to stop compacting, however, is largely dependent on compaction time and empirical judgment based on visual obser- Construction of a coastal levee in Natsui District, vation, and there are no established quantitative criteria. There is Fukushima Prefecture using trapezoidal CSG dam concern, therefore, about problems such as segregation resulting technology from inadvertent failure to perform compaction, incomplete compaction and excessive compaction. To solve these problems, a new T. Okeda, H. Igari, N. Yasuda, Y. Kobayashi and A. Takei dam concrete compaction management system has been developed. The new system directly measures changing concrete vibration with acceleration sensors and analyzes vibration waveforms so that The coastal area of Fukushima Prefecture suffered enormous an objective judgment can be made as to when to stop compacting damage from the tsunami caused by the 2011 off the Pacific coast and numerical data can be recorded. The system makes it possible of Tohoku Earthquake, and most of the coastal levees were dam- to make the best decision as to when to stop compacting, regardless aged catastrophically. Completed in October 2013, Natsui District of the operator’s experience or expertise. Coast was the first coastal levee to be constructed in Fukushima Prefecture as a restoration and reconstruction project. The length of the coastal levee is 920 m, and the crest height (TP; Tokyo Peil) Construction of a tunnel spillway at large water depth is 7.2 m. The levee volume is 60,000 m3, and 40,000 m3 of that is made using CSG (Cemented Sand and Gravel), which was made K. Takahata, R. Yoshioka and A. Konagai with concrete debris from the earthquake together with cement and water. This is the world’s first application of the design and con- To increase of the flood control capacity of the dam which has struction method of trapezoidal CSG dams to a coastal levee. By passed through the half century after completion, the large-scale adopting this method, not only does it have a “persistent” structure tunnel spillway with a diameter of 11.5m was newly constructed toward overflows of sea wave, but both material cost and disposal at the abutment of dam under water of 33m. The most important cost were reduced by using concrete debris from the earthquake, task was a construction of intake shaft of steel pipe sheet pile at the which has to be handled as general waste. In addition, we were upper end of the tunnel which act as an intake part of new spillway able to greatly shorten the construction period: it took about seven and also serves as a temporary coffering, and measures to stop gush months to complete the main part of the coastal levee. out of water at the joint part with tunnel. For solving these engineering problems, we performed stress analysis and quantitatively grasp the stress distribution of the intake shaft in the constructing Trial mix and full-scale trial embankment for RCC dam at stage and joint excavation of tunnel that has been constructed from Nam Ngiep 1 hydropower project the downstream. Based on the result of the analysis, we made monitoring plan of shaft displacement and performed countermeasures Y. Aosaka, T. Seoka, B. A. Forbes, J. Cockcroft, Y. Murakami for reliable water tightness around the intake shaft and tunnel joint- and M. Asakawa ing part. As a result of these countermeasures, the construction of the tunnel under the water was safely completed without suffering by large water gush out from the intake shaft. The Nam Ngiep 1 Hydropower Project (290MW) in Lao PDR is presently under construction (2014-2019). A Roller Compacted Concrete (RCC) gravity dam, 167m height is being built in a nar- Proposing a fully automatic cementitious mix production row V-shaped gorge. A total of 2.3 million cubic metres of RCC is system planned to be placed in 26 months, as a continuous process through wet and dry seasons using the Slope Layer Method (SLM) for M. Fujiwara, I. Miyairi and S. Sakazume placing RCC. The principal materials are cement and fly ash, im- ported from Thailand, and locally quarried sandstone/conglomerate The authors have developed a continuous grading management sys- aggregate. This Paper discusses the programme of off-site and on- tem using a three-dimensional image processor capable of irradi- site trial mixes that were conducted between 2008-2015 to obtain ating line laser light to CSG (cemented sand and gravel) materials a stable, durable and economical RCC mix design, the full-scale on a belt conveyor, calculating the volumes of particles of different trial embankment, and the construction of the left bank wing wall 29 DAMS IN JAPAN - OVERVIEW 20182015 of the regulating dam and the secondary upstream cofferdam to the compaction amount, joint treatment, compressive and direct tensile main dam, that were carried out from 2015-2016. The full-scale strength, in-situ permeability testing, and finally as observed in full trial embankment confirmed and evaluated the variability of RCC section cuts made through the trial embankment by band sawing and the Grout Enriched RCC (GE-RCC), the placement charac- cutting. teristics, with respect to the machinery used, the layers thickness,

C. ICOLD 86th Annual Meeting International Symposium and 26th ICOLD World Congress in Vienna, July 2018

Design of a Tsunami coastal levee using trapezoidal CSG Suruga-trough and Nankai-trough. The planned coastal levee is located on a long sandy beach, parallel to a seaside protection forest technology and quality control during CSG production on the north side. Its location imposed the design requirements for (Coastal of Hamamatsu city) the conservation of valuable fauna and flora, and scenic appear- ance, and for the restoration of the seriously eroded shoreline. The N. Itoh, T. Takada, S. Terada, N. Yasuda, T. Nakashima and M. levee of CSG (Cemented Sand and Gravel) placed at the center and surrounded with embankment are applied for raising the ground Tanaka elevation of the seaside protection forest. The planned coastal levee is required to have tenacity enabling it to withstand overflow In order to mitigate giant tsunami damage predicted to occur on of Tsunami, but strength equal to that of a concrete structure is not the Hamamatsu City Coastline, a coastal levee higher than Level-1 needed, so a CSG structure, which has been developed by dam en- Tsunami is being constructed about 17.5 km from Lake Hamana gineering, is adopted for the internal portion of the levee. Further- to the mouth of the Tenryu River. Here, Level-1 Tsunami is a tidal more, the usage of ICT is also attempted to rationalize and advance wave which occurs as the result of an earthquake of magnitude (M) quality control of CSG material. 8 with the return period of roughly 100 year-150 year cycle along

Theme 3 Flood, spillway and outlet works

A. ICOLD 84th Annual Meeting International Symposium in Johannesburg, May 2016

Planning and design of additional discharge facilities in The arrangement of additional discharge facilities is restricted due to the layout of the existing facilities of the dam. In this paper, Japan we explain the considerations in the planning and design of the additional discharge facilities in accordance with purposes and N. Hakoishi, T. Sakurai and T. Ikeda types of a facility. In addition, we describe the design approach of additional discharge facilities which are to be installed by drilling a Additional discharge facilities to the existing dam are hardly concrete gravity dam. planned in the design and construction stages of the existing dam.

B. 4th Asia Pacific Group Symposium and th9 East Asia Dam Conference, September 2016

Gate operation support table of Ohno flood control dam charge to prevent overtopping are one of the most serious matters for operation managers. In above situation, MOPO (minimum out- against excess flood inflow flow to prevent overtopping) table, which was developed by Public Works Research Institute Japan, was employed by Ohno dam for J. Kashiwai, T. Kubozonoand T. Takada supporting the operation judgment. MOPO is obtained through the gate operation simulation in the large inflow condition which Flood control operation requires smaller discharge than inflow. reaches to the design inflow. If the outflow at the time in the pair of This operation raises water level of a reservoir, and cannot be inflow and water level condition is greater than MOPO, future wa- continued until reservoir water level reaches to the dam design ter level must be controlled under the dam design flood stage with- flood stage. Flood control operation mode should be changed into out extreme outflow increase. This paper will show the simulation overtopping prevention mode in an appropriate way at a certain conditions for the Ohno dam’s MOPO table. They consist of the inflow and water level condition during excess flood inflow. Mode inflow condition, gate movement restrictions and outflow increase changing timing and the gate operation ways for increasing dis- limitations. DAMS IN JAPAN - OVERVIEW 20182015 30

C. ICOLD 85th Annual Meeting International Symposium in Prague, July 2017

Experimental study of ski jump spillway at the Nam Study on scouring phenomena at downstream of dam Ngiep1 Hydropower Project in Laos during flood control

T. Takahashi, Y. Murakami, M. Asakawa, S. Tsutsui and Y. Aosaka Y. Kitamura and S. Takagi

The Nam Ngiep 1 Hydropower Project in Laos is under construc- Funagira Dam was built at the most downstream of the Tenryu tion: two dams and two powerhouses with total installed capacity River in 1977. The spillway facilities were designed to handle the of 290MW. A 167 m roller compacted (RCC) dam is being con- design discharge of up to 11,130 m3/s under gross head of 10m structed in the narrow valley and will be equipped with a ski jump to 18m. The energy dissipation at downstream of the dam was spillway with multiple flip bucket. Hydraulic model tests have been designed as the hydraulic jump-type on the bed protection blocks. carried out in order to confirm the effect of deflectors and alterna- The dam has been experienced several large flood events during tive flip bucket geometries which promote increased longitudinal the last about 40 years after the completion. The protection blocks dispersion of the water jets and diving zones downstream in the were damaged and the scouring downstream foundation of the dam river course. was begun in the early stage, and up to 6,300 measure blocks were continually put on. In recent time, nonetheless, the flood events in 2011, was larger and longer period of flood with maximum flood Development of new maintenance program for scouring about 6.396 m3/s, and the scouring increased to the severe condi- measures at downstream of dam tion at the foot and stability of dam. In this paper the experimental study results and knowledge with the field observation, mathemat- S. Takagi, M. Sato and Y. Kitamura ical model tests, and the vertical 2-dimensional and the fully 3-dimensional hydraulic scale model tests were introduced to evaluate Energy dissipations at downstream of dam have to be sufficient to the scouring processes and to determine the long-term measures. reduce the stream power and to pass the flood discharge safely. The scouring at downstream foundation of dam and spillway structure is especially a major topic in presence of hydraulic structures for Study on validity of the hydroelectric dam operation flood control. By utilizing the obtained information, we will fur- adopted GSM and the information about typhoons ther and continuously make our all efforts to securely carry out the existing erosion measures and long-term measures at downstream H. Takakura, T. Matsubara, E. Nakakita and N. Takada of dam to stabilize the dam, to thoroughly keep and control the environment including the dam and the river, and to respond to the In recent years, unusual rainfalls and floods have increased, and problems found as the results of the measures. They are including social demands are increasing that hydroelectric power dams, checks and reviews for the maintenance and control standards, which have no function for flood-control originally, function as the plans, and countermeasures. In this paper the new maintenance flood-control dam. The long-term rainfall forecast is needed for program was explained and introduced the process of setting up the hydroelectric power dam to have the flood-control function by by the experimental study with the field observation, mathematical lowering reservoir water level with power generation. In this study, model tests, and the hydraulic scale model tests. The program was a new proposed weather and flood forecasting method, which appropriately to be examined through the various observation and combines the efficient formulation of GSM (Japan Meteorologi- tests about the topics of during construction of scouring measures cal Agency’s Global Spectral Model) and the information about and maintenance for the existing dam. typhoons, was applied to Ikehara and Kazeya hydroelectric power dams at Kumano river basin and evaluated. The results showed that the new flood-control method had the applicability to the dam operations in terms of the reductions of the max discharge from the dams.

Theme 4 Earthquakes and dams

A. ICOLD 84th Annual Meeting International Symposium in Johannesburg, May 2016

The seismic analysis of an earth-fill dam on thick tive stress with dynamic analyses using Finite Element Methods (FEM). According to these analyses, the dam’s crest subsidence is liquefiable ground and countermeasures against a large limited after the earthquake due to the restriction of the liquefac- earthquake tion potential by adopting the counterweight filling method.

T. Kato, T. Honda and S. Kawato This paper introduces the seismic analysis of an earth-fill dam on a thick layer of liquefiable ground and countermeasures that can be taken to counteract the effect of a large earthquake by using effec- 31 DAMS IN JAPAN - OVERVIEW 20182015

B. 4th Asia Pacific Group Symposium and th9 East Asia Dam Conference, September 2016

Experimental study on seismic response behavior of fill then the effects of the dam’s shape and the direction of the input wave on the seismic response behaviour were verified. From the dams influenced by dam’s shapes and input wave’s direc- results of the experiment, the point at which the maximum acceler- tions ation values were recorded during the shaking in the stream and the dam axis directions was found to be right above the deepest part of Y. Hayashida, S. Masukawa, I. Asano and H. Tagashira the dam’s valley. It was clarified that the response orthogonal to the shaking direction could arise depending on the shapes of the dam, The characteristics of the seismic behaviour of fill-type dams were the direction, and the dominant frequencies of the input waves. examined by shaking table tests, in which three shapes of dam In particular, in the case of shaking in the dam axis direction, the models, namely, symmetric about both a maximum cross section point at which no response could be incited appeared on the crest and a dam axis, symmetric about only a dam axis, and asymmetric of the dam depending on the shape of the dam and the dominant about both a maximum cross section and a dam axis, were shaken frequencies of input waves. separately in the stream direction and in the dam axis direction, and

C. ICOLD 85th Annual Meeting International Symposium in Prague, July 2017

Study of seismic performance evaluation method for Efficient repairing and reinforcement method for AFRD concrete gravity dams on low stiffness foundation damaged by the earthquake

T. Shiono, C. Yamaguchi, Y. Nakano and T. Tsukada T. Tsukada, M. Shimazaki and T. Mizuno

For evaluation of seismic performance of concrete gravity dams We developed the effective repairing method for asphalt facing of which are constructed on low-stiffness foundation, we should the Yashio dam, asphalt facing rock fill dam (AFRD) constructed consider the permanent settlement of foundation due to earth- for the upper reservoir of the Shiobara pumped storage power quake loading in addition to stress of dam body and foundation. plant of Tokyo Electric Power Company Holdings, where cracks However the Guidelines for Seismic Performance Evaluation of occurred by the 2011 Tohoku earthquake, to complete repairing Dams against Large Earthquakes (draft) in Japan don’t mention works in a short period so as to resume power generation imme- how to estimate the permanent settlement of foundation. So, we diately. The developed repairing method was consisted of asphalt studied the evaluation method, which is using FEM dynamic anal- mastic using asphaltic material developed for the purpose of im- ysis by equivalent linearizing method, modeling the foundation as proving deformation performance under a low temperature, here- non-linear material and calculating the settlement by cumulative inafter we call it “low elastic asphalt”, and asphalt impregnated damage. Then we conducted the centrifugal loading vibration test non-woven sheet. We completed the repairing works in about only and numerical analysis to estimate that the method we studied was one month, because we limited the removing area by covering the reliable enough to be used for the first stage evaluation of seismic low elastic asphalt mastic of 10 cm width and 5 cm thickness, as a performance of concrete gravity dams on low-stiffness foundation. buffer part absorbing the strain, on the cracks leaving in the layer underneath from the forth layer to the bottom layer of the asphalt facing consisted of seven layers. In addition, it was estimated that An experimental study on permeability of soils under shear the cracks occurred by the strain concentration of the crest con- deformation using remodeled torsional shear apparatus crete block joint connecting the asphalt facing, the facing near the concrete block joints were also reinforced using low elastic asphalt A. Hisano and M. Takabatake mixtures.

We remodeled the apparatus for torsional shear test on hollow cy- lindrical specimen of soils in order to examine the relationship be- Seismic analysis based on results of the laboratory shaking tween the shear deformation and the permeability of the impervious table tests for the dam-model material for rock fill dams. As a fundamental approach concerning the permeability change of impervious materials deformed by the M. Matsuura, H. Ieda, H. Tagashira and S. Sato vertical offset, we conducted the permeability test using the apparatus. Firstly, we conducted TEST 1 that was the permeability test As Japan frequently suffers large earthquakes, a safety collation method for test material deformed by turning the swivel in steps, of performance against earthquake for aged fill-dams is an urgent while keeping the test pressure constant. We assumed that the co- issue. But an application of technique to maintain high resistance efficient of permeability obtained from TEST 1 was similar to that to earthquake based on results of quantitative analysis is limited. obtained from JIS A 1218:2009. Secondly, we conducted TEST 2 First we have taken one step of arranging examples which analyzed whose purpose is evaluation of water resistance of deformed test conditions and problems about present design techniques for earth- material against high water pressure as severe condition beyond quake-resistance. The series of the example of the seismic-stability realistic situation. As the result of TEST 1, test material was not analysis for the fill-dams is shown in this paper, in which reduction measured the increasing characteristics of coefficient of permeabil- of undrained strength in saturated zone, liquefaction of dam body ity under shear deformed condition. The result of TEST 2 indicates and foundation and the non-linear property of loose dam body were that consolidation pressure has a influence on the increasing char- taken into account. Then we introduce the results for the shaking acteristic of coefficient of permeability of test material. table tests, which we can demonstrate and inspect the applicability of examination methods for earthquake-resistance. In the tests, six DAMS IN JAPAN - OVERVIEW 20182015 32 cases using silica sand were carried out on the 1G field of a small settlement and the deformation for the tests were investigated. And dam with many sensors and centrifugal force field of 60G corre- we present consideration about diagnosis and its procedure to sup- sponding to an actual dam height. Three cases of the tests were port a rational and appropriate evaluation. conducted in the seepage condition. The response acceleration, the

D. ICOLD 86th Annual Meeting International Symposium and 26th ICOLD World Congress in Vienna, July 2018

Three-dimensional behavior properties and reproduction Study on the mechanism of the peculiar behaviors of analysis of an arch dam during large-scale earthquakes Aratozawa Dam in The 2008 Earthquake

H. Sakamoto, N. Sato and N. Tomida N. Yasuda, N. Matsumoto, M. Naruoka and , Z. Cao

This study analyzed the following earthquake records at the Yagi- During the 2008 Iwate-Miyagi Earthquake (M7.2) of June 14, sawa Dam, which is managed by the Japan Water Agency, in order 2008, seismic motions with the maximum acceleration of 10.24 to clarify the three dimensional behavior of arch dams during cm/s2 in the stream direction were recorded at the foundation bed- large-scale earthquakes: (a) microtremor records measured simul- rock of Aratozawa dam, a rockfill dam located approximately 16km taneously at 14 points, (b) small earthquake measurement records from the epicenter. However, the maximum response acceleration obtained simultaneously by seismographs installed at 6 points, and in the same direction near the center of the dam crest was 5.25 m/ (c) maximum earthquake records (6.56m/s2 at center of dam crest). s2, and the acceleration amplification ratio of the dam body was The behavior at the Yagisawa Dam found in (c) during a 6.56m/s2 far lower than that normally considered for a rockfill dam. Further- earthquake record was difficult to reproduce based on three-dimen- more, it was measured that the crest settled down 19.8 cm after the sional FEM analysis, which is generally used in Japan, but were re- earthquake. In this study the dynamical properties of the embank- produced with high precision by analysis using revised foundation ment materials have been identified with the reproduction analysis ground – dam body – reservoir coupling conditions. of the past earthquakes, and the recorded behaviors of the dam body during the mentioned strong earthquake have been simulated. The generating mechanism of the peculiar earthquake behavior has Studies on extensibility of asphalt face and effective been investigated based on the results of earthquake response anal- reinforcement based on AFRD damaged by the earthquake ysis. Furthermore, in order to understand the deformation mechanism, sliding stability analysis and cumulative damage analysis are T. Tsukada, M. Shimazaki, T. Mizuno and Y. Matsumoto performed. According to the results, the residual deformation of the dam body after the strong earthquake is inferred to be caused by The 2011 Tohoku Earthquake triggered cracking in the asphalt face the shaking settlement of the embankment materials. of Yashio Dam, which extended for 70-80 m from the crest almost running parallel to the abutment on both sides. This asphalt-face rock-fill dam was located about 300 km from the epicenter. The Centrifugal model test for destruction of dam body induced maximum observed acceleration was around 0.05 m/s2 at the by the liquefaction of its foundation foundation and around 0.25 m/s2 at the crest, not necessarily in- tensecompared to the levels envisaged in the design (0.266 m/s2 Y. Hayashida, H. Tagashira and S. Masukawa at the foundation and 1.0 m/s2 at the crest). Nevertheless, the dam was damaged. Therefore, the conditions of cracking were studied Huge earthquakes have been occurred frequently in Japan and there in detail on site in combination with indoor testing and dynamic are about 1200 irrigation fill dams which have passed over 50 years response analysis to reproduce and compute the behavior of the after construction. Some of such irrigation fill dams (especially, dam during the earthquake. As a result, the cracking was presumed earth dams) have the problem about leakage and loss of cross sec- to have appeared when strains concentrated on a block joint of tion by aging. In these dams, countermeasures to constructing im- the crest concrete. The further downward propagation along the pervious zone on the upper slope of dam body as countermeasure slope was probably caused by strains from displacement by the against leakage and reinforcement are adopted frequently. Purpose earthquake and thermal contraction from the drop in the water of this study is to acquire the fundamental scientific knowledge level, which concentrated at the tips of the cracks. Indoor tests and about deformation and destruction behaviors of dam body with simulations by dynamic analysis were conducted to validate the inclined core zoning, especially, in sight of the liquefaction of its presumed causes of crack propagation. A method was devised to foundation which is one of principal factor to induce large defor- repair the cracks while ensuring adequate performance of the as- mation during earthquake. Destruction mechanism of dam body phalt face consisting of a total of seven layers. In this method, only developed by interactions among liquefiable foundation, dam body three layers were cut out and replaced with a material resembling and reserved water are verified by the centrifugal liquefaction ex- a joint sealant that contained polymer-modified asphalt with great periment. From results, it is clarified that dam body effects to the deformation following performance even in cold temperatures. behavior of pore water pressure in the liquefiable layer. Increased The material’s composition was also determined by taking the value of pore water pressure under shaking become several times workability into account. Before the repair work, a simulation test when dam body exists. However, retrofitting at the toe of down- was conducted with a sample to make sure that the method not stream slope of dam body can inhibit the typical increasing of pore involving cutting and replacement down to the bottom layer would water pressure. And it is supposed that behavior of pore water pres- provide comparable or greater deformation following performance sure in liquefiable layer closely related to the deformation behavior than the existing asphalt face. The same material from the repair of dam body. Fracture of dam body with inclined core develop work was used at the crest area that experienced the strain concen- progressively according to the interactions among liquefiable foun- tration. A structure was devised and constructed to follow even a dation and dam body. And it is supposed that deformation of up- large strain after a simulation by numerical analysis. stream slope of dam body is dominant factor to induce catastrophic 33 DAMS IN JAPAN - OVERVIEW 20182015 destruction of dam body. Retrofit at the toe of downstream can of suitable embankment materials, the embankments of many of restrain such deformation and, even though dam body damage sev- these small-scale dams have an insufficient degree of compaction. erally, catastrophic destruction inducing over topping is prevented. The reconstruction of the Fujinuma Dam, a small-scale dam in Fukushima Prefecture, which was destroyed by the Great East Ja- pan Earthquake, incurring loss of human lives, is described in this Discussion on the mechanism of the destruction of a small- paper. The safety standard for the reconstruction of the Fujinuma scale dam by The 2011 Great East Japan Earthquake and Dam was defined as “constructing a safe and reliable dam that is reconstruction and reinforcement overwhelmingly more seismic resistant than the failed old dam,” based on the results of analysis of the causes of the failure of the old dam. The technical goal for the reconstruction was defined as T. Miura, M. Matsuura, T. Tanaka, F. Tatsuoka and Y. Mohri “ensuring the safety of the dam against the largest possible ground motion expected in future.” As the new dam had to be constructed In Japan, where rice farming is the main agricultural activity, the as a high-quality dam with a larger degree of compaction than the advancement of civil engineering technology has facilitated the old one to satisfy the standard and achieve the goal, a standard for development of new paddy fields and new agricultural facilities the degree of saturation, which had not been used in the conven- and there are approximately 210,000 small-scale dams that irri- tional dam construction, was defined for the reconstruction of the gate farmland in areas where there are no large rivers. Many of Fujinuma Dam. The design and the results of the execution control these small-scale dams are earthfill dams. Because of the shortage tests are discussed in this paper.

Theme 5 Reservoir sedimentation and sustainable development

A. ICOLD 84th Annual Meeting International Symposium in Johannesburg, May 2016

Positive effects of reservoir sedimentation management on Development of a bedload transport measuring system for reservoir life: Examples from Japan sediment bypass tunnels in Japan

C Auel, SA Kantoush and T Sumi T. Koshiba, T. Sumi, D. Tsutsumi, S. Kantoush and C. Auel

The effectiveness of different strategies against reservoir sedimen- Sediment Bypass Tunnels are operated to divert sediment around tation is demonstrated herein using data sets of Asahi, Nunobiki reservoirs reducing reservoir sedimentation. A major drawback and Dashidaira reservoirs in Japan. The applied strategies encom- of these tunnels is severe invert abrasion due to high velocity and pass sediment routing with a bypass tunnel, drawdown flushing sediment flows. There is an urgent need to establish innovative during floods and sabo dam construction in the catchment. It is measurement systems of sediment transport rates in SBTs. In this shown that bypassing and flushing are very efficient strategies paper, three bedload measuring systems, namely hydrophones, enlarging reservoir life by 3 to 21 times up to many hundreds of geophones, and newly developed plate microphones are introduced years. Furthermore, it is revealed that also efforts in the catchment, and compared. The Koshibu SBT is planned to operate from 2016. e.g. sabo dam construction, is effective enlarging reservoir life by Plate microphones combined with geophones and other planned 2.4 times. systems are installed in the tunnel. Results of preliminary tests and installation plans of bedload measurement are presented. 2D reproduction analysis of reservoir sedimentation caused by flood A practical example change of river bed environment downstream from dam reservoir by sediment N Sorimachi, K Hashimoto and T Sato replenishment Reservoir sedimentation of an existing hydroelectric dam was Y. Musashi, Y. Nakata, T. Suzuki, M. Oshima and S. Demizu reproduced by two-dimensional numerical analysis. To make the calculation simple, numerical analysis was based on parametric studies. As a result, reservoir sedimentation was reproduced by We reviewed the case of the Nakagawa River, which had one of two-dimensional analysis, in terms of sediment’s volume. In addi- the largest scales of sediment replenishment. Its monitoring results tion, relation between reservoir level and inflow, for the effective are composed of river survey, river bed material survey, biological dredging of sediments, were estimated to some extent. We will research and so on. The results show the changes of river bed con- conduct additional experimental operation and numerical analysis dition such as restoration of river bed materials, the increase in the to obtain more information about moving sediments into the dead ratio of fine sediment on the armored river bed and the expansion storage effectively. of riffle. We estimated the amount of transported sediment by one dimensional analysis of river bed variation. We also examined the effects of sediment replenishment on amount of sediment yield by grain size. DAMS IN JAPAN - OVERVIEW 20182015 34

B. 4th Asia Pacific Group Symposium and th9 East Asia Dam Conference, September 2016

Vertical Multi-Holed Double-Pipe system: A new sediment Abrasion and corrective measures of a sediment bypass suction method utilizing a natural head system at Asahi Dam

A. Hisano, S. Oota and K. Maeda T. Nishikawa, Y. Yamane and Y. Omoto

At present, the sediment removal method using a suction pipe is At the Asahi Dam of Kansai Electric Power Co., Inc., a sediment the subject of research as an effective method for discharge of ac- bypass system was built and in operation in 1998 to take a funda- cumulated sediment in dam reservoirs. Vertical Multi-Holed Dou- mental measure to mitigate impacts by prolonged water turbidity ble-Pipe system is one of these methods and has been researched and sedimentation ascribable to collapse of mountain slopes in the by the authors for the application to an actual reservoir. This system upstream caused by a great flood in 1990. The effectiveness of the is expected to reduce the cost of removing sediment accumulated bypass system has been verified and reported in the past. In the repeatedly around a local place such as the neighborhood of the in- meantime, the tunnel invert has been worn notably by a significant take. This paper explores the following topics: methods and results sediment transport at high velocity and how to improve the effi- of the laboratory tests of the system; the hydraulic design method ciency of periodical maintenance is an issue. This paper describes based on the laboratory tests; and the estimation of sediment con- the abrasion of the tunnel invert of the sediment bypass system centration in the discharge flow. at the Asahi Dam that has been in operation for approximately 15 years, and evaluates possible tunnel maintenance methods using the life-cycle cost based on monitored data of abrasion.

C. ICOLD 85th Annual Meeting International Symposium in Prague, July 2017

An examination of efficient turbid water coagulation tests by parallel plates which simulating the open fissure in the bedrock, and applied it to leakage reduction works. We completed the method using natural coagulant leakage reduction works and we were able to reduce the leakage to our target level. M. Miyakawa, M. Kusumi, T. Ishigami and K. Motoyama

Long term persistent turbidity is a major problem in reservoirs of Measures against the predicted degradations of water Japan and other countries. We are examining the practical methods quality of Makio dam by the volcanic eruption using natural coagulants, such as allophane (clay), which can be deposited in the reservoirs, to prove experimentally the effective- K. Onoshima, H. Imamoto, T. Miyashita and Y. Ishiguro ness of allophanes coagulation performance, and to develop a useful and environmental friendly coagulation method for turbid water. Mt. Ontake erupted on September 27, 2014 and it was the second The experiments conducted in this study provided two important time in recorded history. The distribution and volume of products findings. The first is that, through the laboratory experiments, we by the volcanic eruption were almost similar to those of the previ- proved that the new practical dispersers, which are a cavitation ous eruption in 1979. The catchment of Makio Dam is located at mixer and a high pressure water sprayer, can be used effectively to the foot of Mt. Ontake, therefore the influence of the eruption on disperse allophane. And we confirmed the usage of these dispers- the water quality of the dam reservoir was predicted to be continu- ers raises the zeta potential of allophane. This effect is presumed ing over a long period. In response to this situation, Japan Water to promote coagulation. The second is that the coagulation effect Agency (JWA), the management body for Makio Dam, has collab- at the depth of more than 10 m was confirmed through the field orated with local governments/municipalities concerned and water experiment, where the new dispersers were used. As mentioned users/stakeholders to implement not only efficient water quality above, we can propose more practical, useful, and environmental monitoring but also appropriate measures for water quality conser- friendly treatment method for turbid water using allophane at dam vation while making accurate forecast of discharged turbidity. As a reservoirs. result, the dam has kept supplying water to the downstream continuously without any particular trouble in water use at the moment. Grouting method for dam reservoir foundation by effective Sediments discharging using siphon system demonstration use of ground water flow test at the Republic of Indonesia Wonogiri multipurpose F. Kawashima, T. Tsukada and S. Tsuruta dam

In the bedrock of the Yashio dam reservoir foundation, the upper T. Sumi, H. Itoh, T. Sase, T. Satoh and S. Kantoush reservoir of the Shiobara Pumped Storage Power Plant of Tokyo Electric Power Company Holdings, the high dip angle open fissures are distributed to the deep area, there was relatively large amount The countermeasures by machines for excavation and dredging res- of leakage due to these fissures and we needed to reduce leakage. ervoir sediments have been often used in the past but in the future As the leakage reduction measure, we selected the cement grouting the total cost, including operation and maintenance costs as well at the bottom of the reservoir filled with water, with relatively wide as construction costs and the inhibitory effect of shoreline retreat borehole spacing by effective use of ground water flow. We con- of the coastal region have come to be required in the sediments firmed its applicability by the field tests, research and laboratory countermeasure. In this paper, we report the results of demon- 35 DAMS IN JAPAN - OVERVIEW 20182015 stration tests of sediments countermeasure in Indonesia Wonogiri Control method of water bloom using characteristics of dam including sediments reduction of the reservoir sediments to downstream river by the siphon system using water level differ- reservoir ecosystem ence between reservoir and downstream river water level, not only construction costs but also aims to reduce energy consumption for Y. Iseri, M. Mori, K. Kudo and S. Yamamoto operation and maintenance costs by the siphon system in Indonesia Wonogiri dam. A sufficient water level difference for the drought in In the management of the dam reservoir, water bloom is often the test cannot be reserved by using sediments discharge pipe with produced by an abundance of nutrient salts and causes significant a diameter of 400mm, the system can transport sediments with a damage on water supply including poor scenery, unfavorable water maximum particle size of about 130mm, with an average transport taste and production of toxic substance. Cyanobacteria belongs capacity of 30m3/h in the transport distance of 250m and with to bloom forming Microcystis and most frequently occurs in the sediments discharge per unit power of about 8.1m3/kwh. Siphon reservoirs. They are also known to grow rapidly in high tempera- system has 27 times processing capacity compared the dredging ture environment and are, in fact, in increasing trend in the world system with small pump with a capacity of 0.3m3/kwh. because of the green house effect. This paper introduces the control method of the bloom, including Jet-Shock System for dispersing colony cells into the isolated cells, UV radiation Ship for stopping Density current flux due to bubble plume using a new air cell division and cooperation system to improve ecological purifi- energy system cation function.

E. Furusao, H. Kawasaki, S. Takasu and S. Uchizato Field experiment of bedload transport rate measurement at The Dam Air-energy System (DAS) is a new energy system using sediment bypass tunnel compressed air with high efficiency in dams. Several countermeasure facilities were installed in the Haneji Dam for water quality T. Koshiba, S. Kantoush and T. Sumi improvement as the first full-scale system using DAS. DAS fa- cilitates artificial circulation of water by using a bubble plume For advanced maintenance of sediment bypass tunnels (SBTs), par- caused by the production of compressed air by the DAS. Due to ticularly concerning on the abrasion of the tunnel invert, a monitor- the efficiency of DAS, a large amount of compressed air (9.7 m3/ ing of sediment through tunnel is essential. We developed new bed- min) can create a bubble plume. Field experiments were conducted load measurement systems, namely a plate microphone and a plate to elucidate the flux in the horizontal density currents caused by the vibration sensor. After confirming the high sensitivity and robust- bubble plume. Based on temporal changes in the vertical profiles of ness of these systems by flume experiments, these systems were water temperatures, flow rates of surface currents and intrusion as installed at the outlet of Koshibu SBT, which started operation in the middle layer flow were estimated. This method is applicable to 2016, in Japan. Prior to its commencement of the SBT, on-site cal- the Haneji Dam due to the long residence time of water as hydro- ibration experiment was conducted. In the experiment, sediment is logic characteristics of the Haneji Dam reservoir. It was observed input in the SBT artificially by truck beforehand and flushed them that a large amount of current flux was produced by the DAS-bub- out with clear water from the upstream. The experiment is repeated ble plume system. By comparison of the experimental results with for 10 times with different grain size (5, 10 and 50 mm), volume many previous studies, empirical equations for estimating the flux (1, 3, 5 and 9 m3) and water discharge (5, 10 and 50 m3). Seven in current due to the bubble plume are proposed. sensors of the measurement systems, which installed evenly along the width, successfully recorded the signals of passing sediment. In this paper, practical calibration formula of predicting sediment transport rate by recorded data are developed by analyzing the pat- tern of the 10 experiment cases. Finally, a method to quantify sediment transport rate and a desirable operation of those measurement systems on-site are discussed.

D. ICOLD 86th Annual Meeting International Symposium and 26th ICOLD World Congress in Vienna, July 2018

Observation and Estimation Method of Sediment future, are not under observation yet. In this paper, some consideration to improve the estimation method for sediment discharge Production in Kamanashigawa Basin, Fujikawa River in a watershed were conducted for sediment management in dam System (Toward an Accurate Estimation of Dam Sediment operation, by combining observation data of the sediment transport Volume) obtained by various equipment such as hydrophone, turbidimeter, and that predicted by satellite SAR image interference analysis, in Omukawa River, a right branch of Kamanashigawa, Fujikawa river K. Tomita, Z. Ye, T. Hikita and T. Sumi system, Japan. Using the middle to downstream section of Omu- kawa River (extension L = 8.3 km, gradient 1/58) as a study site, The sediment storage in a dam is usually designed based on the a comparison between the volume of sediment transport obtained cases which have similar watershed condition or sediment dis- by SAR image interference analysis using 9 SAR images acquired charge in the nearby area, but not calculated directly from the sed- by the ALOS-2 satellite passing over JAPAN, and the sediment iment observation data in the watershed. Furthermore, the inflow discharge observed by hydrophone, turmidimeter and sediment trap of sediment due to flood events after dam construction is only pit during 2014-2016 period, is conducted. Some considerations accounted by total sediment volume. Besides, the sediment that were made for the results. The result shows that, although the data flow into dam reservoir during a flood and the unstable sediments show relatively large scattering, an approximate linear correlation reserved in upstream that will become the supply resource in the was recognized. The reason of the difference between two data is DAMS IN JAPAN - OVERVIEW 20182015 36 assumed that sediment discharge is measured in only 2.0m wide Analysis of sedimentation countermeasures in hydropower area with respect to the river width of 72 m, which is not adequate for representing the entire river cross section. dams considering properties of reservoir sedimentation C. Onda, H. Okumura and T. Asahi Case analysis of sediment bypass tunnels (Switzerland, Taiwan, Japan) Sedimentation in hydropower reservoir is one of the most important problems for sustainable power generation. Many our compa- H. Ohori, M. Ono, Y. Takata, G. Nagatani and T. Sumi ny’s dam and reservoirs were installed in post war reconstruction period, then for decades reservoirs have stored much sedimentation Until now, the planning and design of SBT has been performed inside up to sedimentation ratio about 10% because of high degree individually, in accordance with the circumstances of a particular of sediment production and river flow regime. We have trying to dam. In order to systematize design methods for SBT, with this excavate sedimentation out of reservoirs to avoid aggradations of research we created a database of the purpose and specifications upstream riverbed and obstacle for intake and outlet functions. of SBT. We then applied classifications by structural types, and Reprehensive five different type reservoir sediment managements analyzed related characteristics. The target was a set of 15 SBT in considering sediment properties have been really carried out. In Switzerland, Taiwan and Japan. Classification of structures was comparatively large Sakuma dam, provisional transporting inside performed based on the sediment discharge form, the purpose of reservoir is main countermeasure, in near future radical man- the dam, and the main purpose of the SBT. Here, the sediment dis- agement will be required. In comparatively small Futatsuno and charge form refers to whether or not sediment entering upstream Taki dam, current excavating sedimentation volume is enough for of the reservoir is passed through the reservoir. For the analysis of maintaining reservoir size for flow sedimentation. So that sediment SBT characteristics, we analyzed the tunnel design discharge, the routing methods as bypassing will be planned in a hurry. In smaller tunnel structure, and the target grain size of sedimentation, based Setoishi and Yambara dam, sediment sluicing or hydro-suction sed- on the prior structural classifications. We then organized consid- iment removal systems have been already started as test. In spite erations to be taken into account with future SBT planning and of no quick remedy to countermeasure reservoir sedimentation design. dramatically, some methods exist that select suitable options for each reservoir considering with reservoir size, life and basin. Not only the technical feasibility, but also the economic advantages and Research on sediment sluicing operations through dam ecological acceptability should be considered. For sustaining reser- discharge operations in consideration of upstream/ voir and hydropower, reservoir sedimentation management will be downstream riverbed characteristics active and adaptive more and more.

Y. Kitamura and S. Takagi Prediction of environmental effect due to sediment sluicing at a series of three dams Sediment environment changes due to sedimentation in a dam reservoir not only cause changes within the reservoir but also affect a T. Yoshimura, H. Shinya, T. Sumi and N. Onikura wide range of the dam’s upstream/downstream. Sedimentation in a dam reservoir greatly changes the upstream/downstream riverbed With the flood disaster experienced in the Mimikawa River system environment, with effects such as increasing the flood level in the due to Typhoon Nabi in 2005, various problems caused by sedi- upstream area, armor coating and degradation of riverbed of the ment in the river basin became clear, including increased risk of downstream riverbed, and even coastal retreat. Due to this, the im- flooding with rising riverbed levels in damregulating reservoirs, portance of comprehensive sedimentation management, which in- grain coarsening in the downstream river channel with the entrap- cludes not only sedimentation measures targeting the environments ment of sediment in dams, and the destabilization of bridge piers within the dam reservoir but also sediment flushing and sediment in the downstream river channel. As part of an effort to resolve all sluicing (hereinafter referred to as “sluicing”) measures compre- these problems simultaneously, from sediment sluicing at a series hensive sediment management, has been increasing. Sedimentation of dams was implemented. Sluicing is an operation carried out sluicing measures, which are comprehensive sediment manage- when there is river flooding due to typhoons. Dam-regulating reser- ment, have often been implemented. In this paper, the authors ana- voir drawdown is carried out, and sediment flowing into these res- lyze data obtained from hydraulic model experiments and results of ervoirs from the upstream is allowed to flow downstream of dams. numerical analyses regarding measures against riverbed erosion in This paper principally covers 1) an overview of sediment sluicing areas downstream the Funagira Dam, and discuss sediment flushing at dams in the Mimikawa River system, 2) understanding and anal- and sluicing techniques based on dam discharge operations taking ysis of the river environment prior to sluicing, 3) predictions of the the riverbed characteristics upstream and downstream the dam into effect on the river environment due to sluicing, and 4) testing of account. The results obtained indicate that it is possible to estimate these predictions. the amount of sediment outflow from the average riverbed level upstream the dam reservoir and the flood volume; to forecast changes in the flow downstream the dam from the estimated amount of sed- New development of technology for countermeasures iment outflow and the average riverbed level downstream the dam; against barren ground by dam reservoir sediments (Super and to maintain and control the flow. On the basis of the numerical fulvic acid iron) analysis results, the authors also propose adequate gate operations and discharge level operations to control dam sedimentation and T. Toyoda, J. Takimoto, T. Sumi, S. Horiya, Y. Sakai and sluicing as well as the flow downstream the dam. M. Sueyoshi

This time, our research group focused on the effect of high concentrations of fulvic acid produced at the bottom of the dam, using a high concentration fulvic acid iron elution unit, in a real sea area 37 DAMS IN JAPAN - OVERVIEW 20182015 where barren ground is progressing. By conducting demonstration Sediment derivation by bypass tunnel restores downstream experiments on the algae field recovery of the dam reservoir, it is going to develop for the practical application of technological environment development for effective utilization of lake bottom deposits. We have used steelmaking slag made from blast furnace as a material S. Kobayashi, H. Fukuroi, T. Sumi and Y. Takemon to promote dissolution of divalent iron ions in the past development process, but from this time we have found more effective materials, We reviewed studies of the effect of SBT on the downstream en- we have manufactured from electric furnace converter A material vironment to clarify whether SBT has a positive effect on down- containing high concentration divalent iron ions was adopted. This stream, and to understand the key features of SBT that promote the is a material containing high concentrations of divalent iron ions environmental recovery of the degraded reaches. Major results of which is 100 times higher than the steelmaking slag that has been the studies are listed as follows. adopted so far. Regarding the commercialization of this research 1. Below-SBT site in the downstream of dam was more like up- and development overseas, it is scheduled to apply in Korea the stream of dam than above-SBT site in the downstream of dam, in first time in East Asia. In addition, we propose a new calculation terms of bed grain size, microhabitat composition, and invertebrate formula for CO2 absorption (carbon conversion) by seaweed bed community. construction, and the annual fixing by the algae of Japan is esti- 2. Environmental recovery of downstream reaches, evaluated by mated to be about 3 million tons. It is expected that future develop- upstream-downstream similarity in microhabitat composition ment of research and development utilizing this technology will be and invertebrate community, corresponded with the years of SBT commercialized in areas such as tidal banks as a port conservation among the 4 dams. 3. Comparison of among-sites dissimilarity in technology and construction for forming seaweed bed and seawall invertebrate community among 3 types of rivers (non-dam, dam maintenance etc. Research and development in this area has attract- without SBT, dam with SBT) suggested a positive effect of SBT on ed attention as a technique for improving the quality of cultured habitat fragmentation. laver as application technology in recent years, technology for re- 4. Turbidity of downstream during and after floods and red tide oc- storing seaweed beds and improving the production of agricultural currence in the reservoir decreased after the start of SBT. products in recent years. 5. Although bed level didn’t increase constantly, grain size, pool-riffle structure, gravel-bar changed as expected within a several years after the start of SBT. Plan and operation results of Koshibu Dam sediment 6. Invertebrate community of downstream became more like that bypass tunnel of upstream of dam within 2-3 years after the SBT in terms of both taxon richness and taxonomic composition. T. Sakurai, T. Tsujimoto, I. Kunimura, H. Takeuchi and K. Ishida 7. Sediment releases by SBT acted as natural pulse disturbances that lower invertebrates and ecosystem functions, followed by their In order to prevent sedimentation in the reservoir and ensure the rapid recovery. continuity of sediment transport at the river, the Koshibu dam 8. Numerical and field studies showed that the downstream channel sediment bypass tunnel was planned and completed in September becomes steeper and the riverbed becomes unarmored conditions 2016. From the viewpoint of structure, environment and sediment by SBT. Surface grain budget, monitoring plan was examined by the monitoring com- size distribution can change quickly even by one SBT release. mittee and several trial operations have been carried out. Since the 9. Turbidity decreased after the SBT operation. Algae, inverte- purposes of the Koshibu dam is including flood control, irrigation brates, and fish decreased after each event but they recovered to a and power generation, the sediment bypass tunnel is planned to pre-event level soon. operate during the flood control. In order to adapt to the flood con- 10. Although test-run of SBT had been done for several years, there trol rule, two crests placed on the two orifices is designed for the was no evidence of the recovery in the invertebrate community of inlet structure. The target bypassing sediments are gravel having downstream reaches towards an upstream state. a grain size of about 100 mm or less, sand and silt (clay). As a Downstream environment is expected to recover to a pre-dam state countermeasure against abrasion damage caused by the sediment within a few to several years after the start of SBT if surface bed transport, around the gate with a relatively low flow velocity was materials are reworked and exchanged. The downstream recovery protected with “rubber steel” and the downstream section with high by SBT that release mainly fine sediment will be examined by on- flow velocity was protected with steel lining. In the monitoring going monitoring in multiple Japanese dams. plan, the objectives of monitoring at each viewpoint were arranged by selecting suitable methods. In sediment budget monitoring, as the first case of the sediment bypass tunnel in Japan, sediment ob- Challenges of Dam Reservoirs for the Coming Japanese servation devices were installed on the bottom of the tunnel outlet Society and Several Proposals part. After completion of the bypass facility, several trial discharge operations were carried out. Even though the trial discharge was a T. Hamaguchi, H. Mori and H. Ishii small scale compared with the planned maximum bypass discharge and comparatively short time, as a result of monitoring, it was This communication is to introduce the core contents of the report confirmed that there was no problem in gate operation, and no sig- compiled by the special committee of Japan Society of Dam En- nificant abrasion damage and environmental changes in the down- gineers (JSDE) in 2016, which aims to clarify important targets in stream river. Moreover, it was able to estimate the sediment budget planning, operation and maintenance of dam reservoirs, with full and sediment transport characteristics during bypass operations. and adaptive utilization of dam stock for the coming Japanese soci- Regarding abrasion damages, long-term monitoring is needed since ety in mind. Approx. 2,700 existing dam reservoirs play indispens- the flow rate and operation time in the trial discharge was limited. able role in supply of water, energy, mitigation of flood damage, maintenance of normal function of the river flow, and recreational function. With increase of aged dams, there is an increasing number of re-development project of dams, whose major purpose is enhancement of flood control capability and recovery from excessive sedimentation. Importance of “backup” capacity is pointed out here. DAMS IN JAPAN - OVERVIEW 20182015 38

After examining three influencing factors, namely decline in pop- 1. Enhancement of flood control capacity ulation, climate change, and rare but devastating disasters, major 2. Securing water supply in a crisis situation issues will be mitigation of flood damages, maintenance of normal 3. Promotion of hydropower function of the river flow, hydropower, and sediment management. 4. Networking of dam reservoirs at a basin level and efforts for Necessity of flood control capacity for long-term river improve- consensus building ment plan is confirmed. Hydropower’s stabilizing function for so- 5. A method to concretize backup capacity lar and wind power is also focused. A basic framework consisting 6. Improvement in reservoir operation of four phases is presented, to make the stock of dam reservoirs 7. Securing dam safety function fully, with proper maintenance and adaptive operation to 8. Technology development for longer service life of dams changes. They are 1) Long service life, 2) Wise use, 3) Capacity 9. Better understanding of dams and fostering engineers of next increase, and 4) Network use. generation Finally, nine proposals of high priority are shown as follows.

Theme 6. Geology and rock foundation

A. 4th Asia Pacific Group Symposium and th9 East Asia Dam Conference, September 2016

Reduction of ground water flow by promoting clogging the bottom of the reservoir, due to difficulty of forming the grout curtain reaching the low permeable layer of the bedrock. To reduce effect of soil particles the permeability of bed rock with the smaller volume of grout, we invented a method to promote clogging effect artificially by T. Tamai, T. Shiono, N. Sorimachi, T. Tsukada and F. Kawashima spreading soil particles into reservoir water. The soil particles were obtained from the residual horticultural soil after being screened, Grouting was conducted to reduce groundwater flow in the bedrock collected near the reservoir, in order to reduce the cost. This paper of a reservoir of a pumped storage power plant, located in the site summarizes the results and evaluation of laboratory tests, field tests where the ground water level is low. We conducted grouting around and application of the invented method.

B. ICOLD 85th Annual Meeting International Symposium in Prague, July 2017

Dam foundation design for the main dam at Nam Ngiep1 seriously impact the dam stability. In order to evaluate the mechanical properties and the distribution and formation of these weak hydropower project in Laos layers, detailed geological investigations were instigated by conducting core drilling, rock property tests, X-ray diffraction (XRD) T. Tabuchi, Y. Murakami, M. Asakawa, T. Seoka and K. Ueda analysis and computed tomography (CT) scanning. Through a multiple-wedge stability analysis and finite element analysis (FEA), A roller compacted concrete (RCC) gravity dam of 167 m height is a shear key was designed to penetrate part of the weak layers and under construction in Laos. Due to a folded zone in the geology of be incorporated into the dam body to improve the dam stability the right abutment, several weak horizontal layers are distributed against sliding. below the river bed and these were considered to have potential to

C. ICOLD 86th Annual Meeting International Symposium and 26th ICOLD World Congress in Vienna, July 2018

Evaluation of the dam geology and geological risk at the elevation. No outstanding fault has been observed and a box fold has been formed at the steep slope area. Flexural-slip associated Namngiep 1 hydropower plant with fold formation has developed around the fold axis. It is ex- trapolated that flexural-slip occurred before solidification based on T. Seoka, Y. Aosaka, Y. Yoshizu and T. Tabuchi the observation that blocks formed by joint sets intersecting with the bedding planes are observed in the sandstone layer and ductile The surface of the mountain at the dam site is covered by talus deformation are frequently observed in the mudstone layer. Simul- and a stratified structure below has alternating layers of sandstone taneously definite striation of reverse-fault sense harmonized well and mudstone having rock class of CM to CH. On this has been with flexural-slip observed in some fine sandstone indicates that developed the dam site. As general the bedding planes on the both coarse sandstone and fine mudstone had flexural-slip developed in abutment are moderately dipping with 8° in downstream direction semi-brittle and ductile condition in geological time respectively. and 8° in riverbed direction. And around the middle of the dam The weak layers are 8 in number and are confirmed on the bottom axis the dip angle of the bedding plane is 15° to 25° in the same of the dam and both the abutments, and they are issues to consider direction. On the right abutment the fold axis is continuous in the specific strength and continuity of weak layers. Physical properties upstream and downstream directions and geological formation of the rock were determined based on observation of outcrops and shows a steep profile, but it becomes moderate again at the higher drilling cores, in-situ block shear tests and laboratory tests. Physi- 39 DAMS IN JAPAN - OVERVIEW 20182015 cal properties of rock mass were evaluated based on Hoek-Brown rock as the CSG material of dam body, and its dam foundation is failure criterion for each part of the foundation rock. Physical prop- also soft rock. Properties of the soft rock surrounding Apporo dam erties of weak layers were determined based on the shear box tests include slaking caused by cyclic wetting and drying, so various of the disturbed samples, liquid limit tests and plastic limit tests. technical studies were conducted in order to use soft rock as the The total strength of the weak layer can be estimated from the com- foundation bedrock. The dam foundation is extremely uneven so ponent of weak layers. In addition, X-ray diffraction analysis was the excavation procedure was also studied. Slaking tests during the conducted in order to verify that these fine particle fractions in the survey and slaking confirmation tests before construction works weak layers do not include any swelling clay (for example, Smec- showed clearly the slaking characteristic of this bedrock and leads tite) which might significantly degrade physical properties. Besides to the effective countermeasures. The construction works were detailed observation by means of CT scanning was conducted in completed and the first impoundment started in October. order to examine the continuity of a fractured part. Geological risk should be evaluated adequately for the dam construction in the BOT scheme project. The risk to a hydropower project is high Behavior analysis of the underground powerhouse based compared with other infrastructure projects because large amount on precise displacement measurement of project cost depends on geological condition. Therefore, adequate evaluation of geological risk and diversification of geological M. Kashiwayanagi, K. Maeda, N. Shimizu risk are very important factors. In addition, highly accurate geological data helps adequate evaluation of geological risk. Drilling A few damaged pre-stressed anchors were identified in the 40- technology especially is one of the most important factors to sup- year aged underground powerhouse, while no other deterioration port geological evaluation. In this paper, the methods to evaluate in the cavern was found. The underground powerhouse includes the dam foundation rocks are discussed in the feasible study phase output of 220 MW and two generator units. The cavern located to the execution phase. Evaluation of the geological risk and the 100 m beneath the reservoir has the dimension of 23 m wide, 42.25 method to reduce the geological risk are discussed based on actual m high and 70.2 m long. The monitoring of the convergence has geological data. been conducted at two generator sections of the cavern to clarify its long-term performance using a newly developed laser range finder since then. The monitored convergences have behaved stably Slaking countermeasures related to rock contact execution reproducible and been clearly consistent with the yearly and/or the at the soft rocks foundation seasonal fluctuations of the reservoir water depth and the ambient temperature in the cavern. These are less than the unusual convergence which is designated under the assumption of the entire loss S. Yoshimura, S. Takasgi, N. Yasuda, H. Satoh of the support effect as the risk scenario. No concerns are found in Apporo dam is a multi-purpose dam now under construction at the current situation of the cavern so far. the Azuma river in Horonai frontage of Atsuma town, Yufutsu district of Hokkaido prefecture as part of comprehensive development of the Azuma river. The dam is a trapezoidal CSG dam with of 47.2m in height, 47,400,000m3 in total reservoir capacity, and 43,100,000m3 in effective reservoir capacity. Apporo dam uses soft DAMS IN JAPAN - OVERVIEW 20182015 40

Editorial Committee for Dams in Japan

Chef editor: Mr. Shigeru ARIGA Advisor: Mr. Yoshiaki MORIKITA Member: Dr. Masayuki KASHIWAYANAGI Mr. Koutatsu TATEICHI Mr. Yoshihiro KAMEO Mr. Kazuo SAKAMOTO Dr. Shigeru IKEDA Mr. Toru NISHIKAWA Mr. Tatsuya MIZUNO Mr. Toru HINO Mr. Junichi FUKUWATARI Dr. Norihisa MATSUMOTO