river and county in Hebei province
灤 is a rare kanji that names a specific river and county in Hebei province. Its meaning is a proper geographic name rather than a general concept.
灤 combines the water radical 氵 with the phonetic component 欒, which likely indicates the sound and may relate to the place name. The exact historical development is uncertain.
The water radical 氵 on the left hints at a river, while the complex right side 欒 represents the specific name. Picture a map of Hebei with the Luan River winding through it.
For ラン, imagine running water in the Luan River: run -> ラン, and the river flows through the county.