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1.General description of the Sendai river Longitudinal length 137 km Watershed area 1,600km 2 鶴田ダム ( さつま町 ) 川内川上流 ( えびの市 ) 川内川中流 ( さつま町 ) 川内川下流 ( 薩摩川内市 ) 2
2.Flood disaster has occurred in the project site in 2006 More than 1,000mm precipitation in five days It was about 40% amount of average year precipitation Lots of housings are inundated さつま町 図 2-1 既往最大降雨量を超過した雨量観測所 ( で表示 ) 3
2.Photographs during flood event in the project site 虎居町商店街 ( 洪水ピーク時 ) 自衛隊による救出活動 宮都大橋左岸 宮之城橋 虎居町 川内川 宮之城橋左岸 宮都大橋 写真 2-1 さつま町虎居地区被災状況写真 (2006.7.22~23) 4
4.Outline of the project Levee construction Inundated area Short cut Water course excavation 図 1-1 流域の概要 ( 平成 23 年度事業概要川内川河川事務所より ) 5 図 4-1 川内川激特事業の概要図
3.There were many issues to conduct river construction Residents had a high level of mistrust to government They were worrying about influences which should be caused by the construction. Is it really safe? It may destroy our river environment 写真 3-1 2006 年 7 月洪水時のダム放流状況 Cultures and History should be inherited 写真 3-2 Workshop 6
5.Procedure of the project 2006.07.22~23 Flood occurred 2006.10.04 2007.05.22 事業説明会 2007.06.02 実験説明会 2007.09.21 公開実験 2007.11.09 2007.11.22 2007.12.07 2008.01.19 2008.03.15 2008.05.24 2008.06.28 2008.08.01 2008.12.18 2009.03.08 1 Project has been started by government Plan Design work of plan view Do Verified by Hydraulic and landscape model Check Workshop Action 2 Consensus building with residents Detail design 13 回のワークショップ ( 弊社 運営補助分 ) ) 延べ 20 回以上のワークショップを実施 Construction management 図 5-1 虎居地区景観検討の手順フロー 7
7. Hydraulic and landscape model experiment Model was made by Kyushu University(S=1/200) Movable bed in order to show the transition of sand bar Froude similarity Trees are full imitated just like the field (place, density, height ) The model was used not only to verify hydraulic characteristics but also to discuss landscape design 6500 trees Constructed levee Excavated water course 8
7. Hydraulic and landscape model experiment Experiment was opened to public In order to make a good consensus with residents To explain the effect of construction The result was informed to public by broad cast. Housing area Excavated water course Excavated water course 写真 7-3 さつま町の地域住民が参加しての公開実験 ( 九州大学にて ) 9
7-4.Result of the experiment 3 1 2 4 宮之城橋 0.5m 2.0m 1.5m 3 4 1 2 山付堤 Housing area 図 7-1 水理実験結果 10
8.Detail design Traditional stone masonry method was chosen. We can find many traditional stone masonry around the project site 写真 8-1 薩摩興業跡の石積み ( 野面積み ) 写真 8-2 虎居城跡の石積み ( 布目崩し積み ) 11
8.Detail design Landscape model for detail design 写真 8-3 推込分水路の模型 (S=1:500) 写真 8-4 石積み護岸の模型 (S=1:50) 12
8.Detail design Image picture Image pictures Walking path Aerial photo Image picture Conserved trees Excavated water course 虎居城跡 Walking path 図 8-1 虎居城周辺からの鳥瞰図 13
8.Detail design Image pictures Photo 宮之城橋 Image picture Walking path Conserved tree stone masonry 図 8-3 宮都大橋より下流右岸を望む 14
9.Discussions in the field Stone masonry method was discussed with constructors in the field 写真 9-1 研修後 ( 左側 ) と研修前 ( 右側 ) の石積み比較 15
9.Discussions in the field Comparison between landscape model and result of construction 写真 9-4 石積み護岸工の比較 ( 左 : 模型, 右 : 現場 ) 16
9.Discussions in the field Comparison between landscape model and result of construction 写真 9-5 パラペットの比較 ( 左 : 模型, 右 : 現場 ) 写真 9-6 推込分水路の比較 ( 左 : 模型, 右 : 現場 ) 17
10.Appearance after completion Aerial view 宮都大橋 虎居地区 宮之城橋 虎居城跡 宮之城中学校 写真 10-1 虎居地区激特事業全景 18
10.Appearance after completion Excavated water course 宮之城中学校 Native plant vegetation was restored Slope was excavated to follow the landforms 虎居城跡 Overflow levee was constructed to keep environmental flow in main stream 写真 10-2 推込分水路全景 ( 上流より ) 19
10.Appearance after completion Aerial view Mildly-sloped levee was designed Excavated water course Conserved trees 虎居城跡 Mildly-sloped levee 推込分水路 Housing area Walking path Stone masonry 写真 10-5 虎居地区築堤護岸 ( 推込分水路対岸周辺 ) 20
10.Appearance after completion Excavated water course Usual flooding 写真 10-4 推込分水路 ( 平常時と洪水時 ) 21
10.Appearance after completion Constructed masonry stone revetment 殿様池の保全 カヌー乗場 神木の保全 轟ノ瀬 写真 10-10 虎居地区築堤護岸 ( 宮都大橋 ~ 轟大橋 ) 22
10. Appearance after completion Many educational activities for children are conducted in the project site now うなぎ採ったど! さかなつかみ取り大会 E ボート下り (RAC) 川流れ体験! 水神様からの飛び込み! 川遊び指導者育成 (RAC) 23
Thank you for your kind attention! 24