Fukuoka Plain - Fukuoka Heiya

A plain in the northwest of Fukuoka Prefecture, facing Hakata Bay. Its area is about 250 square kilometers. It is mainly alluvial lowlands formed by the deposition of small and medium-sized rivers such as Tatara, Mikasa (Ishido), Naka, Hii, and Muromi, but it also broadly includes the Itoshima Plain to the west and the Munakata Plain to the east. It is bounded by the Sangun and Sefuri mountain ranges in a semicircular shape to the east and south. The area is dotted with isolated land masses such as Mt. Tachibana, Mt. Ogi, Mt. Abura, and Mt. Takasu, as well as plateau-like Paleogene hills and alluvial plateaus, and slopes down in a stepped pattern toward Hakata Bay, but the southeastern part is connected to the Chikugo Plain by the lowlands of the Futsukaichi Tectonic Valley. Due to its proximity to the continent and the Korean Peninsula, it has been developed as an advanced region since ancient times, and is rich in important ruins and historical sites, with Kyushu's largest city, Fukuoka, now well developed. Urbanization is remarkable, but subway construction has been difficult as the city center is located in the middle of an alluvial lowland. Despite the rapid population growth within the area, water shortages are a problem as the water source is small and medium-sized rivers.

[Masaaki Ishiguro]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

福岡県北西部、博多湾(はかたわん)に臨む平野。面積約250平方キロメートル。多々良(たたら)、御笠(みかさ)（石堂(いしどう)）、那珂(なか)、樋井(ひい)、室見(むろみ)などの中小河川の堆積(たいせき)によって形成された沖積低地が中心であるが、広くは西側の糸島平野、東側の宗像平野(むなかたへいや)も含む。東と南を三郡(さんぐん)および脊振(せふり)の両山地によって半円形に限られている。周辺部に立花(たちばな)山、大城(おおぎ)山、油(あぶら)山、高祖(たかす)山などの分離地塊や台地状の古第三紀層丘陵、洪積台地などを散在させて博多湾に向かって階段状に低くなっているが、南東部は二日市構造谷(ふつかいちこうぞうだに)の低地によって筑後(ちくご)平野に通じている。大陸、朝鮮半島に近いため古代より先進地として開け、重要な遺跡や史跡に富み、現在では九州最大の都市福岡市が発達している。都市化が著しいが、都心部が沖積低地の中央に位置するため地下鉄工事は難航した。域内の人口急増に対し、水源が中小河川のため水不足問題が生じている。

［石黒正紀］

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