following a river; along a river
Describes movement or a path that follows the course of a river. Often used with verbs of motion like 行く or 歩く.
We walked along the river toward the village.
This road continues following the river.
Compound of 川 (kawa, 'river') and 伝い (tsutai, 'along, following'), from the verb 伝う (tsutau, 'to go along').