Almost always bound inside 蜿蜒 (winding, snaking). You will rarely see 蜿 standing on its own — treat it as half of that two-character word, used for rivers, roads, and walls that twist along.
Right side 宛 supplies the sound (the tone shifts from wǎn to wān) and a faint hint of meaning, since 宛 itself can mean 'winding'. Same phonetic in 婉 and 碗.
