Readings & Meanings:
I watch the Taiga (historical) dramas on NHK.
The rivers flooded, and this area became submerged.
San-zui, yet again, the three drops of 水 on the left mark this as a water-radical kanji.
The phonetic element is the one we just learned, 可. Remember, the pictogram shows a bent hook.
So, a bending body of water = a river.
Important: 河 & 川
川 means the same thing as 河, and is pronounced the same way.
Look, I know. I KNOW. What. The. Heck.
Google to the rescue. I found a forum thread just about these two kanji (see ref).
While there might be a difference etymologically from the Chinese (可+水=long, bending river with lots of twisty tributaries), there's no real difference in Japanese.
One forum poster says that 川 is mainly used for rivers in Japan and 河 is used for foreign rivers, usually. That's good to remember. Also good to remember is that Japanese people think 河 is the "hard kanji for river."
And just remember 河川 means "rivers" so you'll remember both!
Wondering what kind of shows "Taiga dramas" are? They are the historical dramas that NHK puts on every year. They last for many weeks, following historical figures. One ridiculous one I saw was about a real guy, but it was completely manga-fied. The historical figure was secretly a martial-arts expert, and he avenged people in the night wearing a Tengu mask.
I'm not sure what that one was called, so I couldn't find a clip. Instead, here's a random Taiga clip from Youtube, wherein a guy with an eyepatch has a moral dilemma: