The phrase "sent river" implies that a river has been sent or directed in a certain direction. Synonyms such as "diverted river" or "directed river" could be used to convey the same message. Other synonyms for "sent" could include "dispatched," "transported," or "delivered," all of which could be paired with "river" to create alternative phrasing. For example, "dispatched river" or "transported river" could convey the idea of a river being moved from one place to another. Ultimately, the specific synonym chosen would depend on the context and intended meaning of the phrase.