徳島県高磯山崩壊と貯水池防災

概要

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On July 25, 1892, the north flank of Mt. Takaiso, on the right side midstream of the Naka River, slipped into the valley (fig. 2) and dammed up its channel. After about 50 hours the c]am gave a way and caused a great flood …Aradani Flood. 1. The naturally dammed reservoir had a volume of 72 million m^3 and an area of 3.2km^2. The flood reached the mouth of the river 67km below the dam about 5 or 6 hours later after the breaking of dam. Its uppermost water level is shown with a fine full-1ine in fig. 3. The Nagayasuguchi Reservoir was constructed 4 km downstream from Mt. Takalso. There seems to be a danger of landslides taking place in this area even now. The writer estimated the danger of landslides around the reservoir from several reasons enmaly (fig. 4) I. the distance from the Butsuzo Tectonic Line, II. the existence of thick shale beds, III. the undercut slope of the river, IV. the slope gradient of 40° or more. V. the existence of thick talus deposits. Fig. 4 shows dangerous areas by different hatches, the multihatched area will be must dangerous. 3. The writer estimated the magnitude of the disaster If it happened by the over-flow of Nagayasuguchi Dam, and concluded that the flood would occur on almost the same as Aradani Flood.
地理科学学会の論文
1970-12-14