Water Act Article 81

No enclosing of a sandbank or beach of a waterway for cultivation is allowed unless the authority-in-charge deems such enclosure is not detrimental to water flow or flood control and approval from its superior authority has been obtained.
中文原文 水利法第81條
水道沙洲灘地,不得圍墾。
但經主管機關報准上級主管機關認為無礙水流及洪水之停瀦者,不在此限。

English translation for reference only; the Chinese text prevails. Not legal advice.