Two stations written with the same kanji but pronounced differently — why?

Question

The JR Nara line and the Keihan Uji line are almost parallel on their way through southeastern Kyoto and Uji. In most areas, both have a station and the names are clearly related if not identical (e.g. both have Rokujizou and Oubaku; JR has Momoyama while Keihan has Momoyama-Minamiguchi etc.).

However, there is also a rather interesting pair of stations between Oubaku and Rokujizou: both stations are written 木幡 in kanji yet Keihan gives the pronunciation as こわた while JR gives the pronunciation as こはた. This matches what is heard in the announcements on their respective trains.

I assume that the name corresponds to the name of the surrounding part of Uji. Unfortunately, I don’t know which of the two pronunciations would be correct for that suburb. But how is it possible that the same combination of kanji when used as a name for the same place gives two different pronunciations?

A map showing both stations in Uji.

Answer 1

Historically, は and わ are very closely related sounds. Before the spelling reforms around the end of World War II, the kana は was commonly pronounced in both ways (and of course this survives into modern Japanese in the form of the particle は).

So this is probably a case where the place name was historically こはた but the pronunciation of the は was never fully standardized, and the two different versions still survive in different contexts today.

Incidentally, the Japanese Wikipedia entries for the two stations include a note that in addition to こはた and こわた, there are some nearby placenames that use the same kanji pronounced こばた (rendaku of course being another case of a common sound change that's not always consistently applied). What a very inconsistently pronounced word!