All-surcharge system - All-surcharge method

...Surcharge capacity is a kind of reserve capacity, a capacity to prepare for small floods that may occur in non-flood seasons and abnormal floods during flood seasons. In addition to the restricted water level method mentioned above, there is also the all-surcharge method. This method, which keeps the water level below a certain level throughout the year, ensures a certain flood control capacity at all times, without distinguishing between flood season and non-flood season. It is often used in reservoirs with relatively small watersheds, but has the drawback that flood control is likely to conflict with water utilization plans (Figure 2).

*Some of the terminology used in reference to the "all-surcharge system" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…サーチャージ容量は一種の余裕量の確保であり，非洪水期にもくるかも知れない小洪水や，洪水期の異常洪水などに備えるための容量である。なお，今まで述べた制限水位方式とは別にオールサーチャージ方式と呼ばれるものがある。年間を通じて一定水位以下に下げておくこの方式は，洪水期と非洪水期を区別せずに，つねに一定の洪水調節容量を確保しておくもので，比較的小流域の貯水池でよく用いられるが，治水が利水計画と競合しやすい難点がある(図2)。…

※「オールサーチャージ方式」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