Waju - Waju

These are settlements surrounded by levees, found in the low-lying, alluvial region stretching from Seino, downstream of the Kiso, Ibi, and Nagara rivers in the southwestern part of the Nobi Plain, to the northeastern end of Ise (Mie Prefecture). They are also called "encircled levees" settlements. This area has suffered numerous floods and severe water damage since ancient times. The Satsuma Domain's construction of the three rivers diversion works (Horeki River Control) in 1754 and 1755 (4th and 5th of the Horeki era) in the mid-modern period and the construction of the three major rivers after the Meiji era are well known as large-scale countermeasures. In this area, water dikes were built around settlements and cultivated land (paddy fields) as a flood prevention measure, and these encircled levees are also called "waju." The residents (village people) within the ring ju have not only relied on it for flood prevention, but have also continued to live their lives in a broader sense, with a sense of community that they "live within the ring," in all aspects of life within the ring, including production, the economy, and society. Ring ju are believed to have originated in historical documents from the early modern period (1675 = Enpo 3), where they appear as "Wanouchi" and "Kuruwa," but it is believed that it was only from the mid-modern period onwards that these low-lying, swampy plains became so large that they were considered ring ju areas. Ring ju were initially built on a small scale through the farmers' own desire to develop the area, but later medium- to large-scale structures began to appear with the capital investment of merchants.

The distinctive landscape of the ring ju is that the houses of the village are built on the higher ground within the ring ju, including the surrounding water dikes. Furthermore, in one corner, a particularly high mound of earth is built and surrounded by stone walls, and a storehouse-style "mizuka" (water house) is built on top of it, which can be used for evacuation in case of floods, for storing food, and for preserving household goods. Another unique land use known as "horita" can also be seen. This was devised to prevent "water damage and crop failure" caused by inland flooding within the ring ju, and involves alternating rows of "horita" (dug-up rice fields), which are high rice fields dug up in the low-lying areas within the ring ju, and "horita" (dug-up rice fields), which are dug up into creek-like pits to remove the soil. After World War II, with the land reclamation and land improvement projects and the progress of urbanization, the horita rice fields have almost completely disappeared, and can no longer be seen today. Adjacent ring villages were at odds over flood control, and even today, there are accounts of conflicts between the Owari Domain, a Tokugawa clan relative, and the Ogaki Domain, an outside feudal lord, during the Edo period. Even within the same domain, there were conflicts over the upper and lower reaches of the river, and over slight differences in land elevation. However, flooding decreased with successive river improvement works from the middle to late Meiji period, and especially with the introduction of flood control works using continuous levees after World War II. This led to a decline in the awareness of ring village residents about flood control, and even the destruction of ring village levees led to a drift in disregard for ring villages. However, after the ring village disaster caused by the flooding of the Nagara River in 1976, awareness of the risk of flooding increased, and discussions of reevaluating ring villages began, and the disaster prevention effect of ring village levees, as well as their psychological and social effectiveness, are being reaffirmed. Nevertheless, the awareness of participation in flood control activities, which was once carried out jointly, is declining.

Water floodplain structures similar to ring-shaped rivers can be found in the water towns downstream of the Tone River, in the reclaimed lands of the Ariake Sea, in polders in Western Europe, as well as in reclaimed lands in Europe (Britain and Germany), and in the river basins of the Ganges (India), Brahmaputra (which flows from the Tibet Autonomous Region of China into the Bay of Bengal), Irrawaddy (Myanmar), and Song Khoi (Vietnam).

[Yukio Asaka and Mineaki Kanno]

"Waju (Waju)" by Yasuo Ito and Nobuyoshi Aoki (1979, Gakuseisha)" ▽ "Waju and High Tides" by Shigenobu Ito (1982, Mie Prefecture Document Publishing Association)" ▽ "Waju (Waju) - Its Formation and Transition" by Masuo Ando (1988, Daimeido)" ▽ "The Changing Waju" edited by Yasuo Ito (1996, Kokin Shoin)

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

濃尾(のうび)平野南西部の木曽(きそ)、揖斐(いび)、長良(ながら)三川の下流の西濃(せいのう)から、伊勢(いせ)（三重県）北東端にかけた低湿な沖積地域にみられる、堤防によって囲まれた集落。囲堤(かこいづつみ)集落ともいう。この地域は古くから数多くの洪水にあい、激しい水害を受けてきた。近世中期の1754、55年（宝暦4、5）の御手伝普請(おてつだいふしん)による薩摩(さつま)藩の三川分流工事（宝暦(ほうれき)治水）や明治以後の三大川改修工事はその大規模対策事業としてよく知られる。この地域では洪水防止策として、集落や耕地（水田）の周りに水除堤(みずよけづつみ)を巡らしたが、その囲堤も「輪中」といっている。そして輪中内の居住者（集落民）は輪中を頼りに水防にあたってきたのみならず、広く輪中内での生産や経済・社会などの生活全般について、「輪中で生きる」との共同体意識のもとに生活し続けてきているのが特色である。輪中は、近世前期（1675＝延宝3）の史料に「輪之内」「曲輪(くるわ)」とみえているのがおこりとされるが、この低湿性平野が輪中地域とされるように大規模になったのは近世も中期以後のこととされる。輪中は初めは農民自身の開拓意欲によって小規模ずつつくられていったが、のちには商人の資本投下による中・大規模のものもみられるようになった。

　輪中を特色づける景観としては、周りの水除堤をはじめとして、集落の家は輪中内でも高みの地区に屋敷取りがなされている。さらにその一隅はとくに土盛りを高く築いて石垣で囲み、上に倉庫式の「水塚(みづか)」（水屋）が建てられ、洪水時の避難や食料の貯蔵、家財道具の保存にあてられるようにしている。ほかに「掘田(ほりた)」とよばれる特殊な土地利用もみられる。それは、輪中内でおこる内水氾濫(はんらん)による「水損(すいそん)不作」を防ぐために考え出されたもので、輪中内の低湿部を掘り上げて高くした「掘上げ田」と、その土(ど)取りのためにクリーク状に掘り下げられた「掘田」とが交互に配列されているものである。掘田は、第二次世界大戦後から始まる干拓土地改良事業および都市化の進展でほとんど消滅し、現在は見ることができない。隣り合う各輪中は水防上は対立し、近世の幕藩制下では徳川氏親藩の尾張(おわり)藩域と外様(とざま)大名の大垣藩域との間で、また同一藩域内でも上・下流域間やわずかの地盤の高低差によって対立抗争したことが、いまも語られる。しかし明治中後期以後の相次ぐ河川改修工事、ことに第二次世界大戦後の連続堤による治水工法の導入によって洪水が減少し、それに伴って輪中居住者の水防意識が低下し、さらには輪中堤の取り壊しが行われたりして輪中軽視観が漂い始めつつあった。しかし1976年（昭和51）の長良川の洪水に伴う輪中災害ののちに水害危険意識が高くなって、輪中の見直し論がおこり、輪中堤の防災効果、さらに心理的・社会的な輪中堤の有効性が再認識されている。それでも、かつて共同で行っていた水防活動への参加意識は低下している。

　輪中に似た防水堤施設は、利根(とね)川下流の水郷、有明(ありあけ)海の干拓地、西ヨーロッパのポルダーをはじめ、ヨーロッパ（イギリス、ドイツ）の干拓地、そしてガンジス（インド）、ブラマプトラ（中国チベット自治区からベンガル湾に注ぐ）およびイラワディ（ミャンマー）、ソンコイ（ベトナム）の各河川流域にもみられる。

［浅香幸雄・菅野峰明］

『伊藤安男・青木伸好著『輪中』（1979・学生社）』▽『伊藤重信著『輪中と高潮』（1982・三重県資料刊行会）』▽『安藤万寿男著『輪中（わじゅう）――その形成と推移』（1988・大明堂）』▽『伊藤安男編著『変容する輪中』（1996・古今書院）』

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