inundate, flood, torrent
澇 centers on overwhelming water: a flood, a torrent, or the act of being inundated by a large volume of water.
澇 combines the water radical 氵 with 勞, which likely contributes the sound ロウ. The character expresses flooding or inundation through the water component.
The water radical 氵 beside 勞 suggests water rising and spreading uncontrollably. Picture a great wave (氵) overwhelming everything, like a flood or torrent.
For ロウ, imagine a rowboat being swept away by the flood: row -> ロウ, and the water (氵) inundates the boat.