In case anyone was interested in the answer:

"Being the river with the most excessive silt in the world, the Yellow River gets its name from the muddiness of its water, which bears a perennial ochre-yellow color." per https://www.travelchinaguide.com/river/yellow/geographical-intro.htm.

That's not correct English grammar. You have to put the title in: 'Why is The Yellow River yellow?'