river
河 centers on a large natural watercourse: a river. It is often used for major rivers, especially in Chinese-derived names.
河 combines 氵 (water) with 可, which likely contributes the sound. The character has long been used to refer to rivers, especially the Yellow River.
The water radical 氵 flows beside 可, like a river winding through the land. Think of the three drops as the river's water and 可 as its winding path.
For カ, imagine a river so wide you could drive a car across it: car -> カ, and the river flows on.
Milky Way
mouth of river; estuary
discarded tiles; discards
rivers
large river
Hanoi (Vietnam)
Kawachi (former province located in the east of present-day Osaka Prefecture)
Taiga drama; annual year-long historical drama TV series produced by NHK
(navigable) canal; waterway
puffer fish; blow fish; fugu; globefish; swellfish
dry riverbed; river beach
kappa; mythical water-dwelling creature
glacier
flood plain; river terrace; riverside area; area between river and river bank
Milky Way galaxy; Milky Way; the Galaxy
Mikawa (former province located in the east of present-day Aichi Prefecture)
glacial period; glacial epoch; glacial era; ice age
Suruga (former province located in the central and northern parts of present-day Shizuoka Prefecture)
riverbank; riverside
mountains and rivers; natural surroundings