noise of tramping feet
趵 centers on the sound of feet striking the ground: the noise of tramping or stomping. Its meaning is narrow and onomatopoeic.
趵 combines 足 (foot) with 勺, which likely contributes a phonetic element. The character is rare, and its exact historical development is uncertain.
The left side 足 means foot, and the right side 勺 looks like a stomping motion. Picture feet tramping loudly, making a 'baku' noise.
For ハク, imagine the sound of tramping feet echoing 'haku haku' on a wooden floor: haku -> ハク.