River improvement work - River improvement work

Japanese: 河川改修工事 - かせんかいしゅうこうじ

…In the upper reaches, sabo works are carried out on the slopes and streams of mountain rivers where sediment runoff is common, and landslide prevention works are carried out in landslide areas upstream. Multipurpose dams for flood control and water use, dams for power generation only, and sabo dams are also constructed. In the midstream and below, river improvement works are almost always carried out for flood control and water use, and compared to rivers in other countries, a great deal of technical activity is carried out, and rivers are increasingly being artificially constructed. In river improvement works, river course straightening is carried out to smooth out the natural winding course, and in cases of extremely meandering river courses, new straight courses are excavated or the course is shortened to improve flood flow (shortcuts), and in some cases the old winding river course is used for new land uses. …

From [Flood Control]

…As a countermeasure, sabo works have been continuously carried out in upstream areas all over the country since the mid-Meiji period, and construction methods unique to Japan, such as mountainside sabo and stream sabo, have also been developed (sabo). In the riverbeds that flow down to the plains, river improvement works for flood control are mainly carried out, focusing on levees. In addition to shortcuts and spillways to improve the flow of floodwaters, sometimes flood control basins are also built in the plains to temporarily store part of the floodwaters and return them to the riverbed after the peak of the flood has passed. …

*Some of the terms used in relation to "river improvement work" are explained below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…上流部においては，土砂流出の多い山地河川の山腹や渓流での砂防工事や上流域地すべり地帯での地すべり防止工事が実施されるほか，洪水調節と利水のための多目的ダム，発電専用ダム，砂防ダムの建設などが行われる。中流部以下では，日本の河川の場合はほとんど例外なく治水と利水のために河川改修工事が実施され，諸外国河川に比べきわめて多くの技術的活動が行われ，河川の人工化が進んでいる。河川改修においては，屈曲していた自然流路を滑らかにするような河道整正が行われており，極端な蛇行河道の場合には，新しく直線河道を開削したり，流路を短縮して洪水の疎通をよくする(ショートカット)とともに，屈曲していた旧河道を新しい土地利用に供する例もある。…

【治水】より

…その対策として全国各地の上流域に明治中期以降，継続的に砂防事業が行われており，山腹砂防，渓流砂防ともども日本特有の工法も発達している(砂防)。平野部に流れ下った河道部では，堤防を主体として，治水目的の河川改修工事が行われる。洪水流の流れをよくするためのショートカットや放水路はもとより，ときには平野部でも遊水池を設けて，洪水流の一部を一時的にここに蓄え，洪水のピークが過ぎ去ったのちに再び河道に戻すという方法もとられる。…

※「河川改修工事」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典第２版について | 情報

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