Ash Wednesday (a Christian day of penitence)

rise and fall (of the Roman Empire etc.)

have space between, be open / become empty, unoccupied, vacated / become unused, free / become free (not busy) / become open (of a job etc.)

worship, cult / admiration, reverence

drainage / displacement (water displaced by an object in water) / Alternative spelling of 廃水. wastewater.

warm salt water (used to thaw tuna)

fresh / vivid / rare

few, scarce, meager, little / widow(er)

who / someone

Kyūjitai form of 水文学: hydrology