stop, hinder, place near water
厔 centers on obstruction and location: stopping or hindering movement, and a place near water where one might be stopped or settled.
厔 combines 厂 (cliff or enclosure) with 至 (arrive), suggesting arriving at a cliff or stopping place. The exact historical development is uncertain, but the component relationship likely expresses a place where one is stopped or hindered.
Under a cliff (厂), something arrives (至) and is stopped. Picture a traveler reaching a cliff by the water and being forced to halt.
For シツ, imagine a sheet of water stopping you at the cliff: sheet -> シツ, and the place near water hinders your progress.