name of a river in Shandong, marsh, float
汧 centers on a body of water: a river name, a marsh, or the idea of floating on water. The meanings are connected by water, but the river name is a specific proper noun rather than a general concept.
汧 combines the water radical 氵 with 开, which likely contributes a phonetic element. The character is primarily used as a proper noun for a river, and its historical development beyond that is uncertain.
The water radical 氵 beside 开 suggests a river opening up into a wide marsh, where things can float.
For ケン, imagine a man named Ken floating on a marsh: Ken -> ケン, and he drifts on the water.