柯南，我的天。
while most/all(?) CN speakers probably know what 江 means, it's one of those words that's generally fallen out of modern use aside from a truly impressive number of names – 黄江、长江、浙江、江南、江苏…
When I think of it, same in Japanese? 江东区, 江户川 and so on, but you wouldn't actually use it just to mean "river." Funny that Chinese went for 河 (I think?) and Japanese for 川 in general. (Why we need three different characters for "river" in the first place is beyond me...)