文学作品から見た20世紀前半の隅田川の水質の変遷 Change in Water Quality in the Sumida River in the Early Half of the Twentieth Century Estimated from Literary Works
水質分析資料がない時代の水環境の復元方法として,本研究では文学作品中の水に関する文章に着目した.隅田川を中心とし,東京における文学作品中の水に関する生物指標および視覚的な表現を抽出し,それを現在行われている水域類型区分にあてはめ,20世紀前半の東京の河川の水質を推定した.<br> 文学作品中の文章表現から推定した東京全体の水環境を見ると, 1920年頃にはすでに水質が悪化している河川や水路がかなり存在した. 1940年頃になると汚れた水域が増加しており, 1920年頃から1940年頃にかけて水質が一段と悪化していたことが,この方法により示された.同様の方法を用いて隅田川の水質を推定すると,すでに1905年には浅草付近で著しく汚れていた. 1915年になると,吾妻橋から清洲橋にかけて汚染が顕著で,白鬚橋や永代橋,佃大橋でも水質悪化を示すようになり,汚れた水域が拡大していた. 1935年になると,白鬚橋から永代橋にかけた全域で汚染が顕著になった.本稿では,得られた水質評価と土地利用あるいは工場数,人口変化との比較検討を行い,水質の悪化と人間活動が対応していることを示した.
Historical reconstruction of the aquatic environment has been a matter of interest, but exact data on water quality and water flow and waterscape were lacking before World War II . Many valuable descriptions of the aquatic environment can be found in literary works, newspapers, and documents on local history. Maps are also useful reference materials. The author focuses on descriptions or expressions in literary works, such as novels, essays and poems. Although some descriptions in novels are not objective, it has been assumed that many of the literary works reflect the social and physical background of the time when they were written. Therefore, it was inferred that the landscapes and waterscapes in literary works would be effective data for the reconstruction of the historical aquatic environment.<br> Current water quality standards are applied to the descriptions in literary works. The relevant sentences or phrases are classified into three categories based on the biological water standard applied to the entire Tokyo area, but into five categories based on the Environmental Quality Standard when applied to the Sumida River.<br> The historical water environment from the Meiji Era until the middle of the Showa period in Tokyo was assessed by biological and visual descriptions of water in literary works. Based on the biological water quality standard, the water environment in the entire Tokyo area around 1920 and 1940 was compiled in grid maps. The result shows that several rivers in Tokyo were already polluted before World War II.<br> A detailed study of the water quality of the Sumida River before World War II was carried out with reference to the five categories of the classification. It was inferred that the water quality of the Sumida River around Asakusa in 1905 was already in Class E (heavily polluted water). In 1915, the section between Azuma-bashi and Kiyosu-bashi was in Class E, and at Shirahige-bashi, Eitai-bashi, and Tsukuda-oh-hashi was in Class D (polluted water). In 1935, the whole section from Shirahige-bashi through Eitai-bashi was in Class E (heavily polluted water).<br> Changes in Sumida River water quality at Shirahige-bashi, Azuma-bashi, Ryogoku-bashi and Tsukuda-oh-hashi were also assessed. It is inferred that the water quality of the Sumida River in the early twentieth century was already polluted. Water quality assessment revealed the process of pollution of the Sumida Fiver from the early twentieth century to the 1970s. Although the pollution was reduced in the period around 1925 after the Great Kanto Earthquake in 1923 and in the period around 1945 just after World War II, the river was heavily polluted in the 1970s. However, the situation has improved since then due to the development of sewerage systems and regulations on water qulity control.
- 地理学評論. Ser. A
地理学評論. Ser. A 70(10), 642-660, 1997-10
The Association of Japanese Geographers