久旱逢甘雨
have a welcome rain after a prolonged spell of drought — have a long-felt need satisfied
e.g. 人生快事莫如久旱逢甘雨，他乡遇故知，洞房花烛夜，金榜题名时。
The happiest events in one's life were sweet rains after a long drought, meeting an old acquaintance in an alien land, enjoying wedding-night felicities, and passing the imperial examination with distinction.
