vicinity
滸 centers on the area near water: a waterside, shore, or vicinity by a river or lake.
滸 combines 氵 (water) with 許, which likely contributes the sound and the idea of a place or area, together suggesting a waterside location.
Water 氵 beside 許: imagine a permit (許) to stand by the water's edge, marking the vicinity of the shore.
For コ, picture a small cove by the water: cove -> コ, the quiet vicinity where water meets land.