27 9 Geographical characteristics of flood occurred in Joso city, Ibaraki prefecture

in September, 2015

1

1

1

2

2

Naoko NAGUMO1, Miho OHARA

1, Hisaya SAWANO

1, Hiroko KOUMOTO

2,

and Satoshi TANAKA2

1 ICHARM International Centre for Water Hazard and Risk Management, Public Works Research Institute (ICHARM) 2 Graduate School of Environment and Disaster Research, Tokoha University Ishige and Mitsukaido district of Joso city in Ibaraki prefecture was attacked by heavy flood due to overflow and dike break of Kinu River in September, 2015. Although relatively higher natural levees adjacent to overflow and dike break sites in Ishige district were inundated with the depth of 1.0 m or less, flood water was soon drained to reach floodplain and back marsh behind and expanded southward. Longer and deeper inundation of more than 1.5 m deep around Shinhakkenbori River in Mitsukaido district was caused because developed natural levees prevented to drain flood water smoothly downstream. As issued evacuation orders were not covering all the inundation area, verification of issuing process and evacuation activities of local residents are necessary. Keywords : Kinu river, flood, Joso city, inundation depth, fluvial landform

27 9

100 200 km1 7 11

536.0 mm547.5 mm 526.0 mm

2)

3) 10 6 25.35 km

40.0 km41.75 km

44.1 km45.9 km

4) 12 50 21 km

10 13:005.30 m 8.06 m 5)

9 12 13 17

52

5SALD-3000S SHIMADZU

1

123.64 km2

65,000 27 9 1 18

地域安全学会梗概集 No.37, 2015. 11

－ 69 －

294354

26)

13 16

1356 61

22 3

7)

2

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20 m 1.5 2.0 km1 2 km20 m

15 m9)

17 m12 m

1

20 m

2 km

3 10 18

11 10

11 1340 km2 12)

10 18

13

294 17

2 3

4

－ 70 －

1.0 m1.5 m

0.5 m2.0 m

1 0.4 m

1.2 m 1.6 m1.5 m

1.9 m1.8 m

0.5 m

5site 3 4

site 1 5

site 5 20 cmsite 2

－ 71 －

41.5 m

2 10 10

1511

10 18

2.0 m 34 110 22 14)

2

1 9 10

2.0 m2.0 m

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No. 25282121

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27 9 18 2) 18 2015 3) 18

9 18 12:00 2015 4) 27 9 10

2015 5) 17 18

1 2015 6)

– –36 pp.1-34 2014

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– –36 pp. 55-90 2014

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16 pp.79-91 1992 9)

21 pp.51-59 1996 10)

http://maps.gsi.go.jp 27 9 28 11) http://www.city.joso.lg.jp/kinkyu/

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http://www.gsi.go.jp/BOUSAI/H27.taihuu18gou.html 27 923

13) 27 9http://ecom-plat.jp/nied-cr/group.php?gid=10129

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http://mainichi.jp/select/news/20150912k0000m020086000c.html27 9 29

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