19世紀における伯耆国日野川流域の鉄穴流しにともなう水害と対応

<p>The iron smelting industry in Japan, until the beginning of the 20th century, was run by the traditional iron sand smelting method known as tatara. Iron sand was collected by breaking up weathered granitic rocks and sorting them in running water. This method of mining was known as kanna-nagashi. In the Hino River basin of Tottori Prefecture, kanna-nagashi created large reserves of excess sand which, when carried downriver, caused major flooding in the basin, requiring numerous flood control countermeasures. This paper examines the flooding caused by kanna-nagashi from the Edo Period (1600–1867) in terms of three criteria: (1) riverbank construction, levees, and their related cost sharing; (2) limits imposed on the amount of kanna-nagashi; and (3) the cost sharing and work-sharing arrangements between Hino-gun and Aimi-gun related to river dredging projects. This paper also examines the responses of the new Meiji government and local citizen groups.</p><p>Tottori authorities (han officials) in 1823 decreed that Hino-gun restrict its mining operations, which were resulting in a rise in riverbed levels downstream. Hino-gun agreed to pay for flood prevention measures, and attempted to continue with normal mining operations. However, though smelting company owners and Hino-gun were to bear the costs of riverbed cleanup, in fact payment was often not made right away. Further, in the midst of these circumstances, in 1829 the worst flood of the later Edo Period occurred. After the flood, Hino-gun either made payments or sent laborers directly to Aimi-gun to carry out further riverbed cleanup.</p><p>Later Yonago-cho and Aimi-gun made repeated requests of the Tottori authorities regarding both riverbank maintenance and restricting kanna-nagashi. The authorities, in turn, carried out repairs and various construction projects to strengthen the riverbanks. But by 1861, with the riverbed continuing to rise, the Tottori authorities ordered Hino-gun to cut the number of kanna-nagashi operations by 50％. This resulted in a period where kanna-nagashi was strictly controlled.</p><p>With the Meiji Restoration, many laws were enacted to regulate riparian commerce, but it is impossible to confirm whether any significant development occurred. In fact, smelting operations were almost entirely suspended, and by 1868 riverbeds had deepened. In the early years of the Meiji Era (1868–1912), the regulations and rulings regarding kanna-nagashi made by the Edo Period Tottori authorities were no longer being carried out, and Hino-gun stopped its riverbed cleanup operations in Aimi-gun. In 1885 flooding continued, but 1886 saw the worst flood in the area of the entire Meiji Era. As a result, Tottori Prefecture requested financial aid from Tokyo for riverbank reconstruction. Then in 1888, new regulations relating to kanna-nagashi. Further, the Yonago-cho “Flood Prevention Cooperative” was created, and it bore a portion of the expenses used for riverside construction projects.</p><p>Even so, from the last years of the Edo Period to the latter half of the Meiji Era, the Hino river delta advanced rapidly, pushing the ocean shoreline back at an average annual rate of eleven meters. The rapid lengthening of the river, along with the thriving kanna-nagashi activity resulted in a considerable rise in the level of the riverbed. As a result, after another major flood in 1893, Yonago-cho requested that the government halt all kanna-nagashi activities. But the Kondo family, the head of the smelting company owners, countered by strongly denying any link between kanna-nagashi and flooding.</p><p>[View PDF for the rest of the abstract.]</p>