rising waters, clear deep water
浤 centers on water that is both deep and clear, often with a sense of rising or swelling. The meanings describe a body of water that is not shallow or murky, but rather deep, transparent, and possibly surging upward.
浤 combines the water radical 氵 with 宏, which likely contributes the sound and possibly the idea of vastness or depth. The exact historical development is uncertain.
The water radical 氵 beside 宏 (vast, spacious) suggests a vast, deep body of water. Picture a clear, deep lake whose waters are rising, filling a wide basin.
For コウ, imagine a deep, clear lake that is so vast it could be an ocean: 'ko' as in 'kocean' (a playful blend of 'ko' and 'ocean') -> コウ. The rising waters swell like the tide.