The formation of the part of Tokyo East Lowland(below sea level area)and the uncertainties of flood hazards there: Tokyo East Lowland is characterized by the gather of mouths of the Tone,the Arakawa and the Sumida rivers in a narrow area. Therefore, Edogawa city at their down streams always fears flood disasters, which is the low land less than zero mean sea level. The heavy inundation will happen in the drainage area even pumping up water, in the coastal area by high tide and at any local areas with guerrilla rainfall. Tokyo East Lowland including Edogawa city is on the deep as the maximum of 40m alluvium soil layers, which are composed from loose sands and soft clays. The ground water used to be significantly pumped up for the industry and to obtain methane gas. The significant ground settlement by the dewatering made the land to be below the sea level. If the river dykes were collapsed by the earthquake, the 70% of Edogawa city would be flooded. As Japan is also located just on the course of the typhoons,the huger ones than ever might possibly attack Tokyo. Therefore, in this study the worse cases of the Kathleen typhoon in 1947 were assumed and several typhoon patterns were simulated in Kanto area for the uncertainties of flood hazards. Finally, it was found that the design flood at Yattajima of the Tone river might be exceeded in the case of shifting the course of Kathleen in 1947 by only 50km to the northwest. Therefore, the author has concluded that flood prevention works must be conducted for the such worse situations. It is concluded that Tokyo and Edogawa city are always feared by huge flood disasters never experienced and their dykes will be the key of life line for Tokyo and Japan.
食料の多くを海外からの輸入に頼っている日本は,世界各国が気候変動によって蒙る様々な影響と無縁ではない。本研究は,気候変動による世界の水資源量と食料生産に関する推計モデルを作成し,世界の水の安全保障の観点から我が国の技術的な貢献の在り方について検討することを目的とするものである。 農産物の生産量に関する本推計モデルは,気温上昇による耕作品種の転換や洪水による減収が反映されていないこと,「実際の収穫量は農業用水の充足度のみに左右される」との仮定が前提となっていることなど改良すべき点はあるが,気候変動による降雨量の変化や将来の水資源開発を含む灌漑用水の増減が生産量の推計に反映できるものとなっている点が特筆すべき特徴である。