raindrops falling from the eaves, eaves
霤 centers on water dripping from the edge of a roof: raindrops falling from the eaves, and by extension the eaves themselves.
霤 combines 雨 (rain) with 留, which likely contributes the sound and the idea of water staying or dripping. The character specifically refers to rainwater dripping from the eaves.
Rain 雨 stays 留 on the roof edge, forming droplets that fall from the eaves.
For リュウ, imagine a long line of raindrops queuing up along the eaves: queue -> リュウ, and the drops drip down one by one.