name of a river
涇 is a rare kanji used primarily as the name of a river. Its standalone meaning is tied to that specific geographical reference.
涇 combines 氵 (water) with 巠, which likely contributes the sound. The character was created to name a specific river.
The water radical 氵 beside 巠 suggests a river. Picture the 巠 component as a winding path of water flowing through a landscape.
For ケイ, imagine a river named Kay: Kay -> ケイ. The river's name sounds like the letter K, and the water radical 氵 marks it as a river.