astringent, harsh, uneven, rough
澀 centers on a rough, puckering quality: astringent taste, harsh texture, or uneven surface. The given meanings all describe something that is not smooth or pleasant.
澀 combines 氵 (water) with 歰, a component that likely contributes both sound and the idea of roughness or astringency. The exact historical development of 歰 is uncertain.
Water 氵 beside the complex 歰, which looks like two rough, uneven shapes. Imagine water flowing over a jagged, uneven surface, creating a harsh, astringent sensation.
For ジュウ, imagine a rough, astringent juice that makes you pucker: juice -> ジュウ, and the harsh taste matches the kanji's meaning.