A KAWA RUNS THROUGH IT
The “river kanji” is 98% straightforward. The kun reading of this kanji, kawa, is found not only in the names of rivers, but also in numerous Japanese surnames and place names. Examples of river names are: Yodogawa 淀川, Mogami-gawa 最上川, and Ohaio-gawaオハイオ川. Surnames include Hayakawa 早川, Nakagawa中川, and Maekawa前川, while Ichikawa 市川and Kanagawa-ken 神奈川県are examples of place names that use the kun reading of the character.
The following kun-based general terms are also worth remembering:
川口 かわぐち mouth of a river
川沿い かわぞい along a river
The only fly in the ointment where this kanji is concerned is its low-frequency on reading, セン.
Kasen 河川is a general term for rivers; and this is the only commonly used word where the セン reading appears. Kasen is the basis for some technical terms that involve rivers and water management: