turbulent, noisy, restless
汹 centers on turbulent, agitated motion or sound: water that is rough and restless, or a noisy, unsettled atmosphere.
汹 combines 氵 (water) with 凶, which likely contributes both sound and the idea of something fierce or turbulent. The character is not common in modern Japanese, and its detailed historical development is uncertain.
Water 氵 beside 凶 (which suggests fierceness or misfortune) creates an image of rough, turbulent water that is noisy and restless.
For キョウ, imagine the turbulent water sounding like a loud, echoing 'kyo' as it crashes against the rocks: kyo -> キョウ.