Mostly figurative. 波澜 means great waves, used for dramatic ups and downs in events or emotions; 波澜壮阔 describes a grand, sweeping scene; 推波助澜 means to add fuel to the fire.
Left water radical, the side-form of 水. It fixes the image of big rolling waves on water, which extends to surging emotions and turbulent events. Same family as 波 and 浪.
