ditch
淢 centers on a man-made water channel: a ditch or trench for drainage or irrigation.
淢 combines 氵 (water) with 或, which likely contributes the sound. The exact historical development of 或 in this character is uncertain.
Water 氵 beside 或: picture a ditch dug beside a field, channeling water away.
For ヨク, imagine a yoke of oxen digging a ditch: yoke -> ヨク, and the water flows through the new channel.