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Page 1: 日本の国土と土砂災害の実態 Land of Japan and Sediment-related disaster

日本の国土と土砂災害の実態Land of Japan and Sediment-relat

ed disaster

Page 2: 日本の国土と土砂災害の実態 Land of Japan and Sediment-related disaster

日本の国土の特徴Feature of the Land of Japan

• 大陸プレートと海洋プレートの境界部に位置する島弧   Island arc located on the boundary of continental plate and ocean plate

• 地形が急峻な山地が大半 Steep mountainous area  • 地質が複雑  Complex Geology• 火山が多い  Many volcanoes• 地震が多い Many earthquakes• 降水量が多い(梅雨、台風、            

        降雪等)                                Much rainfall (supplied by rain                    front (Baiu front), typhoon and                   snow)

• 土砂災害の発生が多い                      Many sediment-disasters

Page 3: 日本の国土と土砂災害の実態 Land of Japan and Sediment-related disaster

日本での土砂災害発生件数Number of sediment-disaster in Japan

1996

(出典:国土交通省砂防部ホームページ)( From the homepage of the Ministry of Land, Infrastructure and Transport )

1997 1998 1999 2000 2001( 1996 ~ 2000) 平均 year

Slope failureLandslide

Debris flow

Number of disaster

Page 4: 日本の国土と土砂災害の実態 Land of Japan and Sediment-related disaster

日本の土砂災害危険箇所数Number of sediment-disaster hazard zone in Japa

n• 土石流危険渓流数                       

   Number of debris flow hazard streams : 79,318   (in 1993)• 地滑り危険箇所数                       

     Number of landslide hazard zones : 11,288   (in 1998)• 急傾斜地崩壊危険箇所数                    

  Number of slope failure hazardous places : 86,651   (in 1997)

• 全危険箇所についてハード対策(構造物による対策)を実施するのは困難である                                  It is difficult to implement ‘hard’ mitigation measures (structural mitigation) in all hazard zones.

• 観測と警戒避難 ( ソフト対策 ) が重要               Monitoring, warning and evacuation (‘soft’ measures) is important.

Page 5: 日本の国土と土砂災害の実態 Land of Japan and Sediment-related disaster

観測の目的Purpose of monitoring

Page 6: 日本の国土と土砂災害の実態 Land of Japan and Sediment-related disaster

観測の目的  Purpose of monitoring• 土砂移動現象の解明 ( 誘因→

発生→流下→堆積の過程 )  To make clear the soil movement phenomena (cause → occurrence → flow → sedimentation)

• 発生予測 ( 誘因、前兆現象から )             Prediction of occurrence (from the cause and warning signs)

• 発生の検知       Detection of occurrence

• 危険範囲の予測、対策計画 Prediction of hazard area and mitigation planning

• 予測・警戒避難の精度向上 Improvement of accuracy of prediction, warning and evacuation

• 警戒避難          Warning and evacuation


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