Setagawa River

A river that flows out from the southern end of Lake Biwa in Shiga Prefecture and flows south. In the past, it was also written as Setagawa, Setagawa, and Setagawa. The downstream is called Ujigawa and Yodogawa. The river from its outlet to its confluence with Daitogawa is generally called Setagawa, but under the River Law, it is called Yodogawa. It is 15 kilometers long. It has long been considered important as a waterway connecting Hokuriku and Yamato, and timber for the construction of Todaiji Temple was also transported along it. Seta on the east bank and Ishiyama on the west bank are crossing points on the Tokaido Highway, and have often appeared in history as strategic points. Even today, important transportation routes are concentrated here, including the Setagawa Railway Bridge on the JR Tokaido Main Line, the Setagawa Ohashi Bridge on National Route 1, the Setagawa Bridge on the Tokaido-Sanyo Shinkansen and Meishin Expressway, and the Seta Karahashi Bridge on the old Tokaido Highway. During the Seta River Improvement Works from 1902 to 1908 (Meiji 35-41), the river width was widened to 109 meters at the point 5.5 kilometers from the lake mouth and the water level was lowered by 3.6 meters. Nango Araiseki Weir was also completed in 1905. The current Araiseki is a dam-type weir completed in 1961 (Showa 36) that has an electrically operated water level adjustment system.

[Seiichi Takahashi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

滋賀県の琵琶湖(びわこ)南端から流出して南下する川。古くは勢多川、世多川、勢田川とも書いた。下流は宇治川、淀川(よどがわ)となる。流出口から大戸(だいと)川との合流点までを一般に瀬田川とよぶが、河川法では淀川である。全長15キロメートル。古くから北陸と大和(やまと)とを結ぶ水路として重要視され、東大寺造営用の木材も運搬された。東岸の瀬田、西岸の石山は東海道の渡河点であり、戦略上の要衝としてたびたび歴史上に現れている。現在もJR東海道本線瀬田川鉄橋、国道1号瀬田川大橋、東海道・山陽新幹線と名神高速道路の瀬田川橋、旧東海道の瀬田唐橋(からはし)など重要な交通路が集中している。1902年～1908年（明治35～41）の瀬田川改修工事で、湖口から5.5キロメートル地点の川幅が109メートルに拡幅されて水位が3.6メートル下げられた。1905年には南郷洗堰(なんごうあらいぜき)も完成した。現在の洗堰は1961年（昭和36）完成のダム形式のもので電動式の水位調節が行われる。

［高橋誠一］

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